Canadian Orthopaedic Association 67th Annual Meeting Westin

Canadian Orthopaedic Association 67th Annual Meeting
Westin Hotel, Ottawa, Ontario
June 8-10, 2012
Abstract Supplement
1: Acetabular Cartilage Delamination Flap Viability in CAM-Type Femoroacetabular
Impingement (FAI)
Brad G Meulenkamp, ON; Paul E Beaulé, ON; Denis Gravel, ON; Arturo Cardenas-Blanco,
ON
Purpose: Femoroacetabular impingement (FAI) is a spectrum of hip pathology that is
becoming increasingly recognized as both a source of hip pain and a precursor of
osteoarthritis in young adult patients. Cam-type FAI is characterized by abnormal proximal
femoral anatomy, which may result in delamination of acetabular cartilage at the labralchondral junction. The purpose of this study was to determine the viability of these acetabular
cartilage flaps.
Method: We retrospectively reviewed 12 hips from 11 patients found to have acetabular
cartilage delamination when undergoing surgical dislocation for symptomatic FAI. All surgeries
were performed by the senior author in an academic institution. Demographic data was
collected to determine age at date of surgery, height, weight, and BMI. Hips were given a
Tonnis grade of osteoarthritis based on the most recent plain film x-rays, and alpha angles
-rays. Cartilage flaps were excised at time of surgery and
sent to a single musculoskeletal pathologist for hematoxylin and eosin (H&E) staining for
cartilage viability and characterization.
Results: The mean age at surgery was 30.1 years (range 21-42): one female and 12 male
patients; mean BMI 26.38 (20.8-30.9). Average Tonnis Grade was 1.58 and alpha angle 67.9
(53.0-80.0). Eleven of 12 cartilage specimens demonstrated 90% viability or greater on H&E
staining under light microscopy. One specimen showed 40% viability. Six of 12 specimens
were characterized as predominantly hyaline cartilage, four were mixed hyaline and
fibrocartilage, and two specimens predominantly fibrocartilage.
Conclusion: Acetabular cartilage delamination is known to occur in association with cam-type
FAI, and is often resected at time of surgery. Our histological analysis of these flaps has
demonstrated that they contain a high percent of viable chondrocytes, raising the possibility of
repair (i.e. reattachment versus resection). Further study is needed to direct optimal treatment
of these lesions.
2: Bone Mineral Density Study of the Femoral Neck after MOM Hip Resurfacing: A
Randomized Clinical Trial of Cemented vs. Cementless Femoral Component Fixation
Andrew Tice, ON; Paul E Beaulé, ON; Paul R Kim, ON; Laurent Dinh, ON
Purpose: Neck narrowing after metal on metal (MOM) hip resurfacing (HR) is a concern for
fracture and loosening of the femoral component. Some series have reported incidences of up
to 30% with cemented fixation which has also been associated with thermal necrosis of the
reamed femoral head. The purpose of this study was to quantify bone mineral density of the
femoral neck of a cemented versus cementless femoral component for MOM HR.
Method: One-hundred twenty patients (60 per group: cemented-Conserve Plus and
cementless-CORIN) were recruited: 105 males and 15 females; mean age of 49.4 yrs (20-67);
mean BMI of 28.9(20.3-42.1). BMD was measured in six femoral neck zones on the operative
side and five zones on the contralateral side. Analysis used total contralateral BMD values as
a covariate. Functional scores as well as complications and reoperations were documented.
Results: Compared to the cemented group, the cementless one had greater BMD in zones 1
(p=0.03), 2 (p=0.04), 4 (p<0.001), and 5 (p=0.02) at 6 months post surgery, and in zones 1
(p=0.03), 2 (p=0.01), and 4 (p<0.001) at 1 year. Within-group analyses showed that the
cemented group had greater BMD in zone 1 at the 1-year interval (p=0.01). The cementless
group showed increased BMD in zone 1 at the 6-month interval (p=0.04), and in zones 1
(p=0.01) and 4 (p=0.04) at the 1-year interval. All patients improved significantly from their
baseline functional score (HHS, WOMAC, UCLA). There were no differences in outcome
scores between the two groups. There was one revision in the cemented group (due to
adverse tissue reaction) and none in the cementless group. There were 2 complications in the
cemented group (1 peroneal nerve palsy, 1 acute cup spin out) and 2 in the cementless group
(1 hematoma, 1 posterior column fracture).
Conclusion: Compared with a cemented femoral component, patients receiving a cementless
implant had higher BMD levels at 6 months and 1-year post-operatively. Both groups had
increased BMD over the follow-up period, particularly in zones 1, 3, and 4. Long-term
evaluation is necessary to determine the potential association between BMD and implant
survivorship between component designs.
3: Corrosion at the Head-Neck Interface of large Head Metal-on-Metal Hip Replacements
Urs Peter Wyss, MB; Clive P Duncan, BC; Richard MR Dyrkacz, MB; Donald S Garbuz, BC;
Nelson V Greidanus, BC; Bas A Masri, BC; Thomas R Turgeon, MB; Rizhi Wang, BC
Purpose: Hip heads larger than 40mm were implanted with increasing numbers in the last 1015 years to reduce the incidence of subluxations, and to increase the range of motion. Some
large head metal-on-metal articulation designs have higher revision rates after only a few years
than other successful hip replacements. The main reasons are cup loosening, cysts, and
pseudotumors, which are often associated with moderate to severe pain. The purpose of this
study was to evaluate the severity of the head-neck corrosion of large heads It is possible that
this corrosion can also lead to similar adverse metal reactions as caused by excessive
articulation wear.
Method: Thirteen acetabular cups of one manufacturer were revised of which seven had
pseudotumors and one had small cysts. The stems were still well fixed in all cases, and were
not removed during revision surgery. Full data was available for seven retrieved cups (six
pseudotumors and one with small cysts). The average in vivo time for the seven completely
analyzed cups was 42.6 months. The 12/14 mm taper in the head that articulated with the neck
of the stem was assessed for corrosion and fretting. The taper corrosion and fretting, as well
as the affected area, was scored from zero to three in four quadrants, and in the superior and
inferior regions. The severity and area scores in each section were multiplied resulting in eight
scores for corrosion and eight scores for fretting, producing a possible maximum score for
corrosion of 72 and for fretting of 72 as well.
Results: Six of the seven tapers were corroded with an average corrosion score of 21.0, and
an average fretting score of 2.4. The average corrosion score was about 20% larger in the
inferior region than in the superior region, and the average fretting score was about five times
larger in the inferior region as compared to the superior region. The corrosion rate for the large
head cups is 0.49/month, which is about five times larger than the corrosion rate for a sample
of 59 28 mm metal-on-PE 12/14 mm taper cups. The corresponding fretting rate of 0.06/month
is about 20% larger for the large head cups.
Conclusion: In summary, it appears that larger heads with otherwise the same 12/14 mm
taper have higher corrosion and fretting rates than smaller heads. This is of some concern, as
it is known that higher than normal articulation wear rates can lead to an increased release of
metal particles and increased ion levels in blood. These are possible causes for
hypersensitivity reactions, pseudotumors, and cyst formation. Therefore, it is possible that
higher corrosion rates at the head-neck interface of large heads can also contribute to
pseudotumors and cyst formation.
4: Does Head Size Affect The Rate Of Corrosion And Fretting Damage Along The HeadNeck Interface Of Artificial Hip Joints?
Richard Michael Ryan Dyrkacz, MB; Jan M Brandt, MB; Olanrewaju Ojo, MB; Thomas R
Turgeon, MB; Urs Peter Wyss, MB
Purpose: Corrosion and fretting are problems associated with the head-neck interface of
modular hip prostheses. The goal of this retrieval analysis was to determine if the rate of
corrosion and fretting damage for the head-neck interface was affected by head size. We also
investigated if there was a relationship between corrosion and fretting damage along the headneck interface.
Method: The hip prostheses were obtained from a local implant retrieval database and
consisted of 74 heads and 40 stems manufactured by two companies. We selected modular
hip prostheses that were implanted for at least one month featuring a 28 mm or a 36 mm
diameter head, a 12/14 mm Morse taper, and a metal-on-polyethylene articulation. The
material of all the heads and stems was CoCr alloy. The neck of the stem and the bore of the
head were separated into superior and inferior regions and also divided into four quadrants.
This resulted in eight regions for each of the heads and necks. Each region received a score of
zero to three to represent the severity of corrosion or fretting damage and another score for the
area damaged. Once a region received scores for severity and area, these two scores were
multiplied to form a regional score for corrosion or fretting. For any given head or neck, all of
the regional scores were added together to determine separate corrosion and fretting scores
that were independent of each other. The maximum score for either corrosion or fretting would
be 72 for a head or neck component. Finally, the corrosion and fretting scores were divided by
the implantation time to reveal the corrosion and fretting rate scores.
Results: When examining the corrosion and fretting scores between the two head size groups,
there seemed to be a negligible difference between the two groups. Additionally, there were no
significant differences in the corrosion and fretting scores of the heads and necks from the two
different manufacturing companies. Corrosion and fretting damage were moderately correlated
with each other upon examining the heads (r = 0.706 for the 28 mm head group; r = 0.885 for
the 36 mm head group) and the necks (r = 0.829 for 28 mm head group; r = 0.978 for 36 mm
head group). However, the rate of corrosion and fretting attack was significantly greater in the
36 mm head group in comparison to the 28 mm head group. The rate of corrosion and fretting
attack for the 28 mm head group ranged from 0.1 to 0.3 (corrosion/fretting score per month)
whereas the rate ranged from 0.3 to 2.4 (corrosion/fretting sore per month) for the 36 mm head
group. This may be attributed to a greater torque caused by a larger head size during activities
of daily living.
Conclusion: With the release of metal ions and corrosion products, this may elevate the
concentrations of cobalt and chromium. By having an increase in the concentrations of cobalt
and chromium, this could trigger hypersensitivity and the presence of pseudotumors, which is
similar to what is being observed with metal-on-metal articulations.
5: Optimum position of the Acetabulum in Hip Resurfacing- A Finite Element Analysis
study
Ravindra Gudena, UK; Amin Komeili, AB; Behzad Vafaeian, AB; Jason Werle, AB; Samer
Adeeb, AB; Elrich Marwan, AB; James Powell, AB
Purpose: Metal on metal hip resurfacing arthroplasty is losing its popularity due to
complications secondary to metal wear debris. Component alignment has an important role in
reducing metal wear debris. We created a Finite Element Analysis model to investigate the
effect of acetabular component position on the contact stresses across the bearing surfaces.
The results obtained have identified the optimal position of the acetabular component with the
least contact pressure across the metal on metal bearing.
Method: Three D Finite Element Model (FEM) of the hip including the pelvis, the femoral head
and the implant was developed. The raw 3D geometrical shapes of pelvis and femur were
reconstructed from the Computed Tomography DICOM-files using the MIMICS (Materialise'
Interactive Medical Image Control System) software. The model was then imported into
Geomagic® to generate smooth analytical non-uniform rational b-spline surfaces. The 3D
geometries of the prostheses were reconstructed using a laser scanning device. Assembly of
the components was performed in SolidWorks®, meshed using HyperMesh® (Hyper Works
Suite, ALTAIR), and then exported to ABAQUS Finite Element software. The boundary
conditions of the model simulated single-leg stance with fixed sacroiliac joint and pubic
symphysis and incorporated the active abductor muscle forces. Material properties were
attributed to the cortical bone, cancellous bone, cement and to the implant. The coefficient of
friction at the bearing surfaces was defined as 0.006. The femoral component position was
fixed in five degrees of valgus. The acetabular component was placed in 35, 40, 45 and 50
degrees of inclination coupled with angles of 0, 5, 10, 15, 20, and 25 degrees of anteversion.
Overall, 24 models were prepared to investigate the optimal position associated with the
minimum contact stresses.
Results: Models with smaller inclination and anteversion angles produced the lowest stresses
within the hip resurfacing components. High inclination angles showed consistently higher von
Mises stresses. While the model predicted lower stresses for anteversion angles using 0 and 5
degrees of anteversion angles, this might lead to instability with subluxation and dislocation.
Thus, the optimum range of inclination angles was defined as 35-45 degrees and anteversion
angles as 10-20 degrees. The recommended range of combined anteversion angles from our
model was 22-32 degrees. Inclination angles of greater than 50 degrees and anteversion
angles 25 degrees or greater caused increased contact stress and impingement.
Conclusion: Malposition of the components is related to increased wear and pseudotumor
formation in hip resurfacing arthroplasty. In this study we developed a numerical model which
predicted the range of optimum positions of the acetabular component with the lowest contact
stresses. This study sheds some light on the stresses developed and offers recommendations
for the optimum position of the acetabular component in hip resurfacing. The aim should be to
place the acetabular component in this recommended position thus reducing the risk of wear-
related complications. Optimal implant position will allow hip resurfacing to be a viable option in
young active adults with hip arthritis.
6: Comparison Of Alumina-Alumina To Metal-Polyethylene Bearing Surfaces In THA: A
Randomized Study With 9 To 15 Years Follow-Up
Charles Rivière, QC; Pascal-André Vendittoli, QC; Martin Lavigne, QC; Pauline Lavoie, QC;
Nicolas Duval, QC
Purpose: Achieving best long-term result, especially in active young patients, relies on
multiple factors including surgical technique, implant design and optimal bearing surfaces.
Revision secondary to high wear rate of Metal on Poly (MoP) put this choice on the bottom of
the bearing surface choices when considering THR in young and active patient. Complications
such as adverse reaction to metal debris (ARMD) render using Metal on Metal (MoM) bearing
a concern full option. On the other hand Ceramic on Ceramic bearing surface with improved
acetabular shell and stem design can be reliable alternative bearing surface with significantly
lower complication rate as compare to other conventional or alternative bearing surfaces.
There are no long-term results of randomised study comparing those bearing surfaces. We
previously published a report with 4 to 9 years follow-up and updated it to present long-term
results (9-15 years) of randomized clinical trial that compares MoP and CoC bearing surfaces.
Method: Randomization of 140 patients with age less than 70 years was done for those going
through THA between 1996 and 2001. Hybrid THA was implanted (ceraver osteal) in all
patients. The bearing surfaces for one group (71 patients) was aluminia-aluminia and the
second group (69 patients) was Metal-on-polyethylene. Clinical scores (WOMAC, UCLA and
merle d’aubigné scales) and radiological evaluations (for osteolysis, loosening, wear rate using
Imagica software) were recorded at the average of a maximum follow-up of 12.1 years (9 - 15).
Results: At final follow up, 107 clinical scores was available (107 THR, 55 MoP and 52 CoC)
and only 77 x-ray (39 MoP and 38 CoC) were available to review. Total of 9 patients had to be
lately revised (8 of them was in the MoP group). The causes of revision in the MoP group were
loosening with sever osteolysis (femoral 4 patients, acetabular 1 patient), and sever isolated
liner wear (3 patients). The only revised case from the CoC group was secondary to stem
loosening with sever Femoral osteolysis. Osteolysis were observed in 8 MoP THR compared
to 1 CoC THR, and was significantly associated with wear and annual wear >0,2mm/y. The
average rate of wear was estimated to be 0.19mm/y for the poly group and un-measurable for
ceramic group. Increased cup abduction angle and decreased femoral offset in MoP group
were significantly associated with higher wear rate. Long term functionnal results seems to be
better in aluminia group with a Statistical significant deference concerning post-operative
UCLA score and some items in the Womac one.
Conclusion: The high revision rate in MoP group secondary to wear related complication was
statistically significant if compared to the CoC group. The encouraging long-term result of
alternative bearing surfaces using CoC with a zero incidence of fracture or squeaking can
classify a well-designed CoC bearing on top of bearing surface options especially in young and
active patients.
7: Imageless Navigation Improves Femoral Component Implantation Accuracy using
Conventional Jig Instrumentation
Zachary Morison, ON; Michael Olsen, ON; Emil H Schemitsch, ON
Purpose: This study examines how imageless navigation improves the accuracy of femoral
component implantation using conventional jig instrumentation.
Method: Post-operative digital radiographs were used to assess the position of Birmingham
Hip Resurfacing (BHR) components implanted using a manual jig prior to any experience with
computer-assisted surgery (Cohort One) compared to a cohort of BHR components implanted
with a manual jig after having used imageless navigation (Cohort Two). Cohort One consisted
of 17 patients implanted with BHR components prior to the surgeon having any experience
with imageless navigation, and Cohort Two included 9 patients implanted with BHR prostheses
after the surgeon trained with 187 cases of imageless navigation. All hip resurfacings included
in this study were performed by a single surgeon (EHS) using a conventional lateral pin jig. A
single observer measured the component position in both the coronal and sagittal planes.
Those values measured for the component position were then compared to the pre-operative
planned position determined by the lead surgeon’s (EHS) surgical protocol. Descriptive
statistics were used to calculate the differences between the final component placement and
the target position. A two sample t-test was then used to compare the values from the two
cohorts.
Results: The mean deviation of the stem-shaft angle (SSA) from the target position was
determined to be 5.6 degrees (SD, 4.3°, 95% CI, 3.6°, 7.6°) in Cohort One and 2.2 degrees
(SD, 2.2°, 95% CI, 0.8°, 3.7°) for those in Cohort Two. This difference between the two groups
was calculated to be statistically significant (p = 0.01). The variance of Cohort One was
determined to be 17.6 degrees compared to only 4.9 degrees in Cohort Two. This shows that
the number of outlying implant positions was greatly reduced. With respect to component
version, the mean deviation from the target stem-neck angle (SNA) of Cohort One was 7.3
degrees (SD, 5.3°, 95% CI, 4.8°, 9.9°). Cohort Two had a mean difference of 4.0 degrees (SD,
2.2°, 95% CI, 2.6°, 5.4°), and this value is also significantly less than Cohort One (p =0.03).
The range for the implant positions in Cohort One was -17.2 degrees to 5.8 degrees as
compared to -8.2 degrees to 3.6 degrees. This demonstrated less extreme positioning in
Cohort Two, as four of the 17 implants in Cohort One were considered to be retroverted (>10°).
Conclusion: Our findings show that more accurate and precise implant placement was
achieved after experience with computer-assisted surgery. This may suggest that surgeons
learning the hip resurfacing procedure should undergo training with both the conventional
lateral pin jig and imageless computer navigation in order to curtail surgical complications
during the surgeons’ early cases.
8: Quantification of Rim Notches in Retrieved Acetabular Polyethylene Liners using
Micro-Computed Tomography
Matthew Teeter, ON; Nicholas Paterson, ON; Steven JM MacDonald, ON; Richard McCalden,
ON; James L Howard, ON; Douglas Naudie, ON
Purpose: Recent literature suggests that unsupported crosslinked acetabular liner designs
may have increased susceptibility for crack initiation. Unsupported rims using an external linerlocking mechanism have demonstrated notching patterns, even at short implant durations, that
may be a point of crack origin and rim failure. The purpose of this work was to examine
whether (1) symmetrical notching patterns and rim cracks existed and demonstrated similar
morphological properties in retrieved crosslinked and non-crosslinked liners, (2)
microcomputed tomography (micro-CT) was able to quantify the dimensions of these notches
and examine underlying subsurface changes; and (3) whether the dimensions of these
notches correlated with their duration of implantation.
Method: From 14 patients, we retrieved ten crosslinked and four non-crosslinked liners of the
same design that had been in-vivo for an average of 2.03 years. Liners were microscopically
examined to determine the presence of cracks and rim notches and then scanned using microCT to quantify notch dimensions and determine subsurface changes to the polyethylene.
Results: All liners demonstrated identical notching patterns in the anti-rotational scallops of the
unsupported rim. Micro-CT scans demonstrated no signs of crack initiation or rim failure, and
were able to accurately quantify the notch dimensions. Of the three dimensions, only the
length vs. implant duration regression in the non-crosslinked group was significantly different
(r2 = 0.949, p = 0.026) from zero. Notches appeared early (< 1 month) and remained relatively
stable in size even at midterm durations of implantation in both cohorts.
Conclusion: The finding that notches exist in the anti-rotational scallop of this liner model has
only recently been reported. Our intent was to confirm the etiology of these notches and their
susceptibility to becoming cracks, which may in turn jeopardize the longevity of the implant.
Our results suggest that the notching patterns caused by liner-cup micromotion may be more
indicative of creep deformation than cracking, as they do not progress markedly over longer
durations of implantation. Unsupported acetabular liner designs that use an external linerlocking mechanism may not be more susceptible to crack propagation and rim failure. We
recognize that most implant manufacturers are moving away from uncaptured acetabular liner
designs and towards a fully captured liner locking mechanism without external anti-rotation
scallops. Nonetheless, the findings of this study remain relevant to those surgeons who have
treated and continue to follow patients who have received this type of liner, and to all those
involved in the design and manufacture of future implant designs.
9: Surface Damage Characteristics on Thirty-Five Retrieved Ceramic-on-Ceramic Hip
Replacements
Trevor C Gascoyne, MB; Thomas R Turgeon, MB; Jan M Brandt, MB
Purpose: Ceramic-on-ceramic (C-C) total hip replacements (THRs) are an attractive option for
young, active patients. However, more clinical data is necessary to establish the reasons of
failure of contemporary C-C THRs in vivo. The objective of the present study was to assess the
surface damage on retrieved C-C THRs and determine possible influential factors that may
explain their in vivo performance.
Method: Thirty-five C-C retrievals of material type Biolox® Forte (n=28) and Biolox® Delta
(n=7) were collected after a mean of 3.7 ± 3.2 years in vivo. Semi-quantitative surface damage
assessment and contact profilometry were performed on all retrievals to obtain both a damage
score (DS) and microscopic assessment of the types of surface damage, such as metaltransfer and stripe-wear areas. Scanning electron microscope (SEM) images were obtained of
two femoral heads displaying areas of typical surface damage.
Results: All retrievals showed evidence of macroscopic surface damage. The implantation
period correlated with the damage score (DS) of the femoral heads (r=0.573, p <0.001) and
the acetabular cups (r= 0.565, p<0.001). However, the metal-transfer DS of the femoral heads
did not correlate with implantation period (r=0.185, p=0.29). Patient age and body mass index
(BMI) did not correlate with DS. Surface roughness of metal-transfer areas were positively
skewed (additive metal transfer) while the stripe-wear areas were negatively skewed (grain
removal), as evidenced by SEM analysis. Four patients reported squeaking in their C-C THRs;
one of which was a 54 yr-old male patient who completed three full marathons with his implant.
The DS for this retrieval was below average, with metal-transfer being the only damage
feature. Fracture of the acetabular liner occurred in three patients, all of which had
malpositioned components. Stripe-wear was seen on one Biolox® Delta C-C THR which had
been implanted for 5 years in a 48 year-old female patient.
Conclusion: The overall DS and the stripe-wear DS correlated with implantation period,
whereas the DS for metal-transfer did not. This finding may indicate that metal-transfer, which
can occur during primary surgery during open hip reduction, may have a relationship with
stripe-wear. The presence of metal-transfer on the ceramic surface is believed to cause a local
alteration of the implant tribology which may facilitate stripe-wear surface damage via an
adhesive wear mechanism. Therefore, direct contact between the Ti-alloy acetabular shell and
the ceramic femoral head should be avoided at primary surgery. Ceramic-on-ceramic THRs
remain an attractive option for young, active patients, but care must be taken during
implantation to appropriately position the acetabular cup and to avoid unwanted metal-transfer
as such alteration at the bearing interface may change implant tribology.
10: A Comparison of Stereology, Structural Rigidity and a Novel Measure of 3D Bone
Connectivity in the Assessment of Torsional Strength and Stiffness in a Mouse Tibia
Fracture Model
David Wright, ON; Diane Nam, ON; Yufa Wang, ON; Maarten Beek, ON; Cari M Whyne, ON
Purpose: Although the majority of long bone fractures heal successfully, due to the high
incidence of these injuries there exists a need for effective evaluation and treatment methods
for the 5-10% that progress to non-union. Accurate methods to quantitatively assess fracture
healing are important to understanding both normal and pathologic bone healing. Healing of a
bone fracture is ultimately described by the mechanical stability of the fracture callus. The
development of non-invasive quantitative tools to assess stability is important for both clinical
applications and pre-clinical studies. The objective of this study was to develop a novel μCTbased measure of three-dimensional bone connectivity and to compare its ability to assess
fracture callus mechanical stability to previously described measures.
Method: Mid-shaft unilateral tibia fractures were produced via a diaphyseal osteotomy in 10
mice pre-stabilized with an intramedullary pin. At 28 days post fracture, μCT images were
acquired of the harvested tibiae (8μm resolution) adjacent to calibration phantoms. Stereologic
parameters were quantified based on 3D callus geometry and mineralization, including
torsional rigidity calculated based on the axial μCT slices. Biomechanical torsion testing was
conducted to determine maximum torque and torsional stiffness. Post failure μCT images
acquired of the bone fragments were used to identify the failure surfaces. Connectivity and
torsional rigidity were then evaluated based on these failure surfaces.
Results: Stereologic measurements of the callus were found to be significantly correlated to
torsional strength and stiffness (R2=0.601 and R2=0.787, respectively for bone volume),
whereas no significant correlations were found between 2D minimum torsional rigidity and
mechanical strength or stiffness in contrast to previous investigations. A moderate correlation
was found for 2D average torsional rigidity and stiffness (R2=0.504). Bone connectivity
parameters local to the failure surface, specifically the surface area and torsional rigidity of
connected bone, were found to significantly correlate with mechanical stiffness, and proved
superior to previously developed 2D measures of torsional rigidity (R2=0.615 to 0.663).
Visualization of the failure surfaces demonstrated a consistent failure pattern indicative of the
applied torsional loading, with locations of the failure surfaces involving the fracture callus at
varying levels.
Conclusion: The results of this proof of concept work indicate the potential utility of these novel
connectivity and torsional rigidity analyses in non-invasive assessment of fracture callus
stability based on identified failure surfaces. Pre-fracture identification of failure surfaces and
the application of connectivity/rigidity analyses to other fracture models (healing stages,
complexity of fracture, loading patterns) will determine the ultimate effectiveness of this new
approach.
11: Effect Of Neonatal Mice Exposure To Diethystilbesterol On Intervertebral Disc In
Male And Female Adult Progeny Subjected To Swimming Exercise
Rahul Gawri, QC; Sora AlRowas, QC; Rahul Gawri, QC; Rami Haddad, QC; Lorraine
Chalifour, QC; John Antoniou, QC; Fackson Mwale, QC
Purpose: Neonatal exposure to Diethylstilbestrol (DES) has been shown to adversely affect a
number of estrogen sensitive tissues, including bone. Effects of in utero DES exposure have
also been shown to affect the third generation. Environmental exposure to estrogens was
shown to be higher than anticipated. The aim of this study is to determine the effect of in utero
exposure to DES on the intervertebral disc (IVD) of adult mice.
Method: Pregnant C57/bl mice were injected with either vehicle (peanut oil) or one of three
doses of DES (0.1, 1.0, and 10.0 µg/kg/day) at 11-14 days of gestation. A minimum of 3
dames was set for each group. Pups were then allowed to grow to adulthood without further
intervention until three months of age. At this point mice were randomized into two groups; one
with a once daily swimming regimen which started as five min. and was escalated to a
maximum of 1 h. The second group were left to their normal activity level and considered
sedentary. All animals were sacrificed at exactly 4 months of age. The lumbar segment of the
spines was dissected from 3 animals per group for histological evaluation and were stained
with 0.1% Safranin O and counter stained with 0.02% Fast Green. Three measurements of
disc height were taken per disc and the means compared for control vs. DES exposed mice.
Whole intervertebral discs were isolated, digested proteoglycan content was measured using
the DMMB assay.
Results: Parameters associated with IVD degeneration were found to have higher scores in
DES exposed mice vs. Controls. Clefts in the NP were only significantly increased in the
female swim group at 0.1 µg/kg/day whereas the female sedentary group showed significant
increases at all three doses of. NP clefting was less evident in males, where the male swim
group showed a significant increase at 0.1 and 1.0 µg/kg/day and the male sedentary group
showed a significant increase at 10.0 µg/kg/day .Tears in the AF showed a similar pattern as
NP clefting, where the female swim group was only affected at 0.1 µg/kg/day and the female
sedentary group showed significant increases at all three doses. Swimming caused an overall
worsening of scores in females. Males were less affected by swimming than females.
Proteoglycan content in the intervertebral disc was significantly decreased at 0.1μg/kg/day and
1.0 μg/kg/day. A significant increase was noted at10.0 μg/kg/day as compared to control.
Conclusion: The intervertebral disc was recently shown to be an estrogen-sensitive tissue.
This had a clinical effect in obese postmenopausal women undergoing hormone replacement
therapy.Our study shows that DES in utero exposure can cause nuclear extrusion and affect
the intervertebral disc. The mechanisms of the effects of DES are however not well understood
and further studies are necessary. This study might shed light on the possible increased risk of
disc degeneration in the sons and daughters of mothers exposed during gestation, as well as
their children.
12: Fracture Healing With Endothelial Progenitor Cells (EPCs) in a Bone Defect Model: A
MicroCT and Biomechanical Comparison with Mesenchymal Stem Cells (MSCs)
Aaron Nauth, ON; Ru Li, ON; Ravi Purushuttam, ON; Erion Qamirani, ON; Emil H
Schemitsch, ON
Purpose: The purpose of this study was to compare the effects of two types of stem/progenitor
cells on the healing of critical sized bone defects in an animal model. Endothelial Progenitor
Cells (EPCs), a novel cell type with previously demonstrated effects on angiogenesis, were
compared to both a control group, and a treatment group of Mesenchymal Stem Cells (MSCs)
using microCT, biomechanical testing, and Laser Doppler Imaging of blood flow at the fracture
site. The hypothesis was that EPCs would demonstrate both superior bone healing and
angiogenesis, when compared to the control group and MSC group.
Method: EPCs and MSCs were isolated from the bone marrow of syngeneic rats by differential
culture and grown ex vivo. Subsequently the cells were harvested, seeded on a gelfoam
scaffold, and implanted into a 5mm segmental defect in a rat femur that had been stabilized
with a plate and screws. Bone healing was assessed by microCT and biomechanical testing.
The capacity of cell treatment for therapeutic angiogenesis was assessed by histology and
physiologically, using laser doppler to assess blood flow at the fracture site. ANOVA was used
to test for significant differences between the groups, and a p-value of <0.05 was considered
statistically significant.
Results: MicroCT comparison of the EPC group (n=14) versus the control (n=14) and MSC
groups (n=14) showed significantly superior bone formation in the EPC group at the bone
defect site for all parameters tested. Biomechanical testing demonstrated superior torsional
strength and stiffness in the EPC group versus control and MSC groups. Laser Doppler
assessment showed significantly more soft tissue and bone blood flow at 2 and 3 weeks in the
EPC group versus the control and MSC groups. More blood vessel formation was observed in
the EPC group versus controls on the basis of histology at 3 weeks.
Conclusion: The results of this study demonstrate that EPCs are effective as cell-based
therapy for healing critical sized bone defects in a rat model. In this model EPCs demonstrated
superiority to MSCs with regards to angiogenesis and bone healing. These results strongly
suggest that EPCs are effective for therapeutic angiogenesis and osteogenesis in fracture
healing. There is a clinical need for effective strategies in the management of traumatic bone
defects and non-unions. Investigation into the use of MSCs as an effective alternative to
autologous bone grafting has failed to translate into clinical use. It is possible that EPCs are
more effective at the regeneration of bone in segmental defects because of their synergistic
effect on angiogenesis and osteogenesis. Further research into EPC based therapies for
fracture healing is warranted.
13: HR-pQCT Measured Bone Microarchitecture and Estimated Bone Strength Can
Classify Postmenopausal Women With and Without Previous Forearm Fractures
Kyle K Nishiyama, AB; Heather M Macdonald, BC; David A Hanley, AB; Steven K Boyd, AB
Purpose: Measures of bone microstructure and estimates of bone strength can be obtained
with high-resolution pQCT (HR-pQCT); however, it is unclear if these parameters can be used
to classify people with fractures. Our objective was to determine if HR-pQCT measurements
and finite element (FE) estimates of bone strength could distinguish between women with and
without low-trauma forearm fracture.
Method: We studied postmenopausal women in the Calgary cohort of the Canadian
Multicentre Osteoporosis Study (CaMos) for whom we had 10-year fracture data and HRpQCT (XtremeCT, Scanco Medical AG) scans at the completion of the study. During the
follow-up, 14 women reported low trauma forearm fractures and were each randomly matched
by age (+/- one year) to two women without fractures (Total N = 42, 72.9 ± 8.3 yrs.). In addition
to standard HR-pQCT measurements (Boutroy et al. 2005), we measured cortical thickness,
porosity (Buie et al. 2007; Nishiyama et al. 2010), finite element ultimate stress, and the portion
of the load carried by the cortical and trabecular regions (MacNeil and Boyd 2007) in all
subjects. We used DXA to measure femoral neck (FN) and lumbar spine (LS) areal BMD.
Support vector machines (SVM; WEKA, University of Waikato) were used to classify women
with and without fracture. A 10-fold cross validation scheme was used to gauge the accuracy
and generalizability of the model.
Results: The first model was based on all HR-pQCT and FE parameters, the second model
used FE measurements alone, and the third model used DXA aBMD (LS and FN) alone. The
SVM based on all parameters correctly classified 35 of the 42 subjects in the cross validation
(Accuracy = 83.3%, Sensitivity = 73.3%, Specificity = 88.9%, Kappa = 0.63, ROC AUC = 0.84).
Using only FE parameters, 34 subjects were correctly classified (Accuracy = 81.0%, Sensitivity
= 66.7%, Specificity = 91.7%, Kappa = 0.60, ROC AUC = 0.81). Areal BMD was not able to
distinguish the fracture cases resulting in 28 correct control subjects (Accuracy = 66.7%,
Sensitivity = 66.7%, Specificity = 0.0%, Kappa = 0.00, ROC AUC = 0.50).
Conclusion: Combined HR-pQCT and FE measurements and FE measurements alone had
good accuracy classifying women with forearm fractures vs. age-matched controls, while FN
and LS DXA measurements failed to classify subjects. HR-pQCT may help to predict
individuals at risk of forearm fracture in a prospective study and form a basis to identify which
parameters from HR-pQCT and FE analysis are critical for assessing fracture risk.
14: Mast Cells and Their Role in Bone Regeneration
Michael H Wang, QC; Michael B Sullivan, QC; Xuejiao Li, QC; Janet E Henderson, QC; Paul
A Martineau, QC
Purpose: Tissue engineering through mast cell-induced bone regeneration has emerged as a
novel idea that can offer the advantages of autologous bone graft transplantation for skeletal
reconstruction without associated limitations of suitable donor sites and shortage of donor
tissue. Recent technological advances in micro computed tomography (Micro CT) now allow
bone micro architecture to be investigated in addition to standard histological methods.
Previous research has not established the specific role of mast cells in bone regeneration and
has not explored the timing of bone healing. Therefore, the current study has two objectives: 1)
To demonstrate whether bone regeneration will be significantly disturbed in mast cell deficient
mice; and 2) To establish the timing of bone healing in wildtype and mast cell deficient mice.
Method: Femoral cortical window defect surgeries were performed on male and female
C57Bl6/J strain mice, with ages ranging from 16-20 weeks, from both wildtype and mast cell
deficient genotypes. As a model for bone regeneration, a cortical window defect with
dimensions of 1mm x 3mm penetrating from bone cortex to bone marrow was generated
bilaterally on mice femurs. After mice were euthanized at postoperative zero, two, and four
weeks, femurs were scanned using Micro CT. Quantification of percentage bone volume was
performed by analyzing bone volume fraction (BV/TV) on a region of interest within the window
defect where bone healing occurred. A non-parametric Mann-Whitney U-test with a
significance value of α=0.05 was used to evaluate the difference in bone healing between
wildtype and mast cell deficient mice at each of the time points.
Results: When genotypes were compared, wildtype mice started with the same bone volume
fraction as mast cell deficient mice at baseline postoperative zero weeks (p=0.517). Wildtype
mice showed significantly higher BV/TV compared to mast cell deficient mice at postoperative
two weeks (p=0.042). Wildtype mice and mast cell deficient mice ultimately achieved similar
bone volume fraction at postoperative four weeks (p=0.104). When time points were
compared, both genotypes showed significantly higher BV/TV at postoperative two weeks and
postoperative four weeks relative to the baseline postoperative zero weeks. Mast cell deficient
mice showed significantly higher BV/TV at postoperative four weeks relative to postoperative
two weeks (p=0.011), but this difference was absent in wildtype mice.
Conclusion: Bone regeneration still proceeds in the absence of mast cells. However, there is
a delay in the bone healing of mast cell deficient mice compared to wildtype mice. This delay in
bone regeneration warrants histological investigation to further strengthen Micro CT data and
possibly suggest a molecular explanation for this phenomenon, such as delayed osteoblast
recruitment.
15: The Effect of Photodynamic Therapy (PDT) on Long Bone Fracture Healing
Margarete K Akens, ON; David Wright, ON; Sadiya Yousef, ON; Diane Nam, ON; Albert JM
Yee, ON; Brian C Wilson, ON; Cari M Whyne, ON
Purpose: Comminuted fractures resulting from high impact trauma can result in delayed
healing or non-union. Despite currently available treatments to reduce the risk of infection
and/or enhance bone healing, such as the use of antibiotic-impregnated beads or bonemorphogenetic proteins, these fractures can take up to a year to fully heal. Photodynamic
therapy (PDT) is a non-surgical, non-ionizing minimally invasive local treatment, which has
been successfully applied to treat multiple types of cancer and skin diseases. Surprisingly,
recent findings from studies aimed at understanding the impact of PDT on vertebral
metastases have shown that PDT rapidly improved vertebral bone strength, stiffness and
architecture. Based on these observations, the aim of this study was to explore the potential of
PDT to enhance healing in traumatic long bone fractures.
Method: A comminuted tibia fracture was generated under general anaesthesia in 11 adult
female Sprague-Dawley rats. Prior to fracture generation a 0.8 mm Kirschner wire was placed
inside the medullary canal. The unilateral fracture was generated in the mid-tibia with a custom
drop weight impact apparatus (500g). The rats were randomly allocated to 3 groups: control
(no treatment), PDT applied 1 day (1d) or 7 days (7d) post-fracture. PDT treatment was
administered using the photosensitizer BPD-MA (1.0 mg/kg; Visudyne). Fifteen minutes later,
laser-light (690nm; 75J) was administered to the fracture site. The rats were euthanized 4
weeks after fracture generation and their tibiae were harvested. μCT images at an isotropic 14
μm/voxel resolution (SkyScan 1172 High Resolution MicroCT System, Skyscan, Belgium) were
acquired of the fracture site and callus for 3D architectural analysis (CTAn, Skyscan).
Results: All rats recovered well from the fracture generation and PDT treatments. The total
bone volume (TV), including callus formation, of the fracture site increased from 148±43mm^3
in the control group, to 157±59mm^3 in the PDT 1d group (6%) and to 175±25mm^3 in the
PDT 7d group (18%). Similarly, the bone volume within the callus (BV) increased from
75±8mm^3 (control), to 78±19mm^3 (1d-PDT) and 85±11mm^3 (7d-PDT).
Conclusion: PDT treatment of the fractured rat tibiae resulted in an increase of bone
formation as compared to control untreated fractures, despite the high variability in the
generation of the comminuted fractures. Further, the relative increases (compared to control) in
both bone and callus volume in the 7d PDT group was found to be ~3 times higher than in the
1d PDT group. This suggests that the tissue response to PDT stimulation may be dependent
on the fracture healing remodeling stage. If PDT is able to enhance fracture healing in complex
fractures it may provide a cost-effective local minimally invasive treatment for long bone
fractures at risk for impaired bone healing, even in situations where there is a delay in medical
care.
16: The Effect of Radial Head Excision and Arthroplasty on Medial Collateral Ligament
Tension
Louis M Ferreira, ON; Katherine E Fay, ON; Emily A Lalone, ON; James A Johnson, ON;
Graham JW King, ON
Purpose: Displaced comminuted radial head (RH) fractures, primary and post-traumatic
osteoarthritis, and rheumatoid arthritis are often treated with RH excision or arthroplasty. RH
excision has been predicted by some biomechanical studies to increase tension in the medial
collateral ligament (MCL). However, the effects of RH excision and arthroplasty on the loading
characteristics of the MCL have not been quantified experimentally. The purpose of this in-vitro
study was to determine the effect of RH excision and arthroplasty on the magnitude of MCL
tension during elbow flexion. We hypothesized that tension in the MCL would increase with RH
excision, and that RH arthroplasty would restore MCL tension levels similar to that of the native
RH state.
Method: Five cadaveric elbows underwent active flexion with the arm in the vertical and valgus
orientations using a motion simulator, and with the forearm fixed in neutral rotation. Tension in
the anterior bundle of the MCL was measured with a custom-built transducer interlaced with
the MCL. Trials were performed for the native RH, RH excised, and RH arthroplasty conditions.
Results: Increasing flexion angle tended to increase MCL tension for all trials. In the vertical
orientation, average MCL tension over the whole flexion range was: native RH = 24.4±19.2 N,
RH excised = 44.5±24.4 N, and RH arthroplasty = 29.9±24.8 N. Due to data acquisition
difficulties, results were not collected for one specimen in the vertical orientation, and no
significant effect of RH condition on MCL tension was detected (p = 0.06). In the valgus
orientation, average MCL tension over the whole flexion range was: native RH = 79.7±29.0 N,
RH excised = 97.3±27.2 N, and RH arthroplasty = 88.0±31.2 N. Tension was greater for RH
excised than native RH (p=0.006). There was no difference in tension between the native RH
and the RH arthroplasty (p=0.1).
Conclusion: Tension in the MCL increased with elbow flexion, indicating that other structures
are responsible for joint stability near full extension, and that the MCL is recruited at increased
flexion angles. In other words, the MCL is an important valgus stabilizer in mid-flexion. This invitro study demonstrates that MCL tension increases following radial head excision, and is
restored to native levels following radial head arthroplasty. Radial head arthroplasty decreases
MCL tension levels compared to radial head excision and, therefore, may reduce the incidence
of cubitus valgus deformities which have been reported following radial head excision.
17: Localized Correction Of Thin-Bone Geometry And X-Ray Intensity Information In
Clinical CT Images
Amirreza R Pakdel, ON; Normand Robert, ON; Jeffrey Fialkov, ON; Cari M Whyne, ON
Purpose: The capability to construct patient-specific finite element (FE) models to simulate the
in vivo biomechanical environment of the skeleton holds great promise for the design of
effective treatments for traumatic injuries, deformities, and numerous pathological conditions.
The most feasible means of constructing such FE models relies on segmentation of cortical
and trabecular bone structures in x-ray computed tomography (CT) images. To date, accuracy
of the constructed models has been limited by the resolution of clinical CT scanners, in
particular with respect to delineation of thickness and intensity measurements in compact thinbone regions, such as those found in the pelvis and the craniofacial skeleton. This study
presents an automated algorithm for localized correction of thin-bone geometry and x-ray
intensity information in CT datasets.
Method: A method is presented for estimating the true intensity profile of thin-bones (<1.0mm
thickness), which exploits the x-ray attenuation and material density information inherent in
clinical CT data sets. This implementation models the overall result of limited pixel size, partial
volume, and other blurring effects of high contrast areas by convolution of an idealized
rectangular function with a Gaussian function. Using local cortical bone intensity and the
integral area of a line profile sampled normal to the bone surface as inputs, a Gaussian
function is computed as the point-spread function (PSF). Deconvolution of the sampled profile
with the PSF yields an approximated representation of the true thin-bone profile. Custom CT
phantoms were first imaged (0.23x0.23x0.625 voxel size) to validate the method (GE
Lightspeed VCT). A cadaveric head was then imaged (0.48x0.48x0.625 voxel size) and the
deconvoultion method applied to the maxillary sinus. Micro-CT scans (Explore Locus, GE)
were acquired of the excised maxillary sinus to serve as a gold standard for both intensity and
geometry measures.
Results: Based on the phantom and micro-CT data, the proposed method provides thickness
estimates of cortical thin-bone features (0.25 - 0.8mm thick) to within 12% of their true
thickness. This compares to >100% thickness overestimation and intensity underestimations
errors observed for thin-bones by threshold segmentation of the original CT images.
Conclusion: The presented method is a viable means of correcting for the typically observed
thickness overestimation and intensity underestimations of sub-millimetre cortical thin-bone
features. This provides a significant enhancement in resolution of CT values, which can be
used to improve segmentation of clinical CT scans. Consequently, this will have a direct impact
on the accuracy of CT based patient specific FE models containing thin-bones, such as the
craniofacial skeleton, scapula and pelvis. Future work will extend this algorithm to improve
accuracy in stratification of cortical shell/trabecular bone structures.
18: Comparison of Outcomes and Survivorship Between Patients of Different Age
Groups Following Total Knee Arthroplasty
Christopher E Robert, ON; James L Howard, ON; Douglas Naudie, ON; James P McAuley,
ON; Richard McCalden, ON; Robert B Bourne, ON; Lyndsay Somerville, ON; Steven JM
MacDonald, ON
Purpose: Total knee arthroplasty is being performed with increasing frequency in younger
patients. The literature has demonstrated that patient satisfaction correlates with clinical
outcomes according to the KSS, WOMAC and SF-12. The purpose of this study was to
evaluate and compare the survivorship (5 and 10 year) and clinical outcomes of patients of
different age groups that underwent TKR at our institution.
Method: A retrospective review based on a prospective database was performed on 6,708
consecutive patients that underwent primary TKA between January 1996 to December 2009.
Patients were then divided into 3 groups based on their age: <55, 55-70 and >70 years.
Clinical outcomes were assessed using the WOMAC, SF-12 and Knee Society Score (KSS).
The outcome score change was determined by subtracting the preoperative score from the
most recent available postoperative score. The outcome score change was then compared
between the 3 age groups. Kaplan-Meier analysis was performed on each group of patients to
calculate survivorship at 5 and 10yrs with revision for any reason being the endpoint.
Results: Comparing the <55, 55-70 and >70 age groups respectively, there was a statistically
significantly difference in the WOMAC total change score (32 vs 31 vs 26, p<0.0001). This
pattern of change was also found when the WOMAC was broken down into its subscales
including pain, stiffness and function. There was also a statistically significant difference in the
change in Knee Society Score favoring the younger populations (<55rys: 78.9 vs 55-70yrs:
76.0 vs >70yrs: 69.0). The Kaplan-Meier survivorship for the <55, 55-70, and >70 years age
groups at 5 years was 95.5%, 97.2% and 98.1% and at 10 years was 92.2%, 95.9% and
97.6% respectively. Revision secondary to infection was the most frequent cause for failure in
all groups.
Conclusion: This study has shown that younger patients experience better clinical outcomes
following TKA according to the KSS, WOMAC and SF-12, but lower survivorship, when
compared to older patient populations. TKA is an excellent treatment for arthritis of the knee
even in younger patients.
19: Inconsistencies between Navigation Data and X-rays in Total Knee Arthroplasty are
System Dependent.
Alberto Carli, QC; Avishai Reuven, QC; Josue Yang, QC; Yaron Brin, QC; John Antoniou,
QC; David Zukor, QC
Purpose: Computer assisted Orthopaedic Surgery for Total Knee Arthroplasty (TKA) has been
shown to improve limb alignment and implant position compared to conventional TKA.
Positioning of implants during image free navigation surgery is guided by a digital model
formulated from computer software tracking bony landmarks specified by the surgeon.
Previous work by our group revealed that inconsistencies exist between intraoperative
navigation alignment data and post-operative weight bearing x-rays. The purpose of the
current study was to determine if such inconsistencies were software dependent and if utilizing
an alternative image free navigation system changed the incidence of significant implant
misalignment.
Method: Two cohorts of consecutive patients underwent unilateral TKA by a single surgeon
using intraoperative navigation. For each cohort, comprising of fifty-eight and thirty-one
patients respectively, a different commercially available image-free computer assisted
navigation system was utilized. Final intraoperative implant alignment data was collected
prospectively and the following three parameters were retained for analysis: 1) the final
mechanical axis of the operated extremity; 2) the coronal angle of the tibial implant; 3) the
coronal angle of the femoral implant. This intraoperative data were then compared to the same
three parameters retrospectively measured from full length lower extremity weight bearing xrays taken six-weeks following surgery. Values taken from digital x-rays in their native DICOM
format were measured by two individuals who did not participate in the surgical procedures.
Comparisons between navigation and x-ray measurements were made with paired T-tests.
Significant misalignment was defined as greater than 3 degrees in at least one of the three
measured parameters.
Results: All patients underwent surgery and successfully completed their postoperative weight
bearing x-rays. In the first cohort, a statistically significant difference was found in the coronal
angle of the tibial component measured from intraoperative data compared to weight bearing
x-rays (p = 0.04). No significant difference was found for the mechanical axis or the coronal
angle of the femoral component. In the second cohort, utilizing a different navigation system, a
significant difference was found versus x-rays for both the mechanical axis (p<0.01) and
coronal tibial angle (p<0.01). Furthermore, more patients with measurements indicating
significant misalignment were found in the second cohort (32%) compared to the first (24%).
Conclusion: Deviations between intraoperative navigation data and postoperative weight
bearing x-rays differ between different commercially available image-free navigation systems.
Such deviations can affect the incidence of significant misalignment in the mechanical axis and
coronal angle of the femoral implants and can potentially affect clinical outcome.
20: Long Term Survivorship of the AMK and Genesis II Total Knee Replacement With a
Minimum 10 Year Follow-up: A Comparative Analysis
Darryl Collings, ON; James L Howard, ON; James P McAuley, ON; Douglas Naudie, ON;
Richard McCalden, ON; Steven JM MacDonald, ON; Robert B Bourne, ON
Purpose: Since the first modern total knee arthroplasty (TKA) in 1972, there have been
numerous implant designs. Two such implants, the AMK (Depuy, Warsaw, IN) and Genesis II
(Smith and Nephew, Memphis, TN) have been used extensively in our institution. The purpose
of this study was to compare the long-term survivorship of the AMK and Genesis II TKA.
Method: Between 1988 and 2000, 709 Genesis II and 1074 (659 cemented) AMK primary total
knee replacements (TKA) were performed on 604 and 843 patients respectively. Ethics
approval was obtained and a retrospective chart and database review was performed.
Demographics, TKA indication, KSCRS, SF-12, and WOMAC outcomes were collected.
Revision rate, reason for revision, and KM survivorship curves were calculated using SPSS
software. Mean pre-and post-operative KSCS, SF-12 and WOMAC were also compared, as
well as the change in score for each group.
Results: In the Genesis II group, pre-operative diagnosis was osteoarthritis in 665 (93.79%),
inflammatory arthritis in 33 (4.65%), and other 11 (1.55%). At 10-15 years, 20 revisions (2.8%)
were performed. The most common reason for revision was infection, at nine (1.3% overall,
45% of revisions). Excluding infections, Kaplan-Meier survivorship at five and 10 years was
99.1% (95% CI 98.7-99.5), and 98.3% (95% CI 97.8-98.8) respectively, with no revision
performed beyond nine years. In the AMK group, pre-operative diagnosis was 590 (89.5%)
osteoarthritis, 54 (8.2%) inflammatory arthritis, and 15 (2.3%) other. At 10-22 years, 50 (7.6%)
revisions were performed in the cemented AMK group, p<0.001. The most common reason for
revision was aseptic loosening (1.2% overall, 25% of revisions). Eight revisions were
performed for infection (1.2%), p = 0.926. Kaplan-Meier survivorship at five and 10 years was
97.8% (95% CI 97.2-88.4), and 95.1% (95% CI 94.2-96.0) respectively, with no revision
performed beyond 13.5 years. Overall Kaplan-Meier distribution was statistically different
between the two groups, p<0.001.
Conclusion: These results support the hypothesis that there is a lower overall revision rate
and less component related failure with the Genesis II total knee arthroplasty implant
compared to the AMK total knee arthroplasty implant.
21: Medial vs. Lateral High Tibial Osteotomy Converted to Total Knee Arthroplasty: A
Comparison of Outcomes
Stephen Preston, ON; James L Howard, ON; Douglas Naudie, ON; James P McAuley, ON;
Richard McCalden, ON; Steven JM MacDonald, ON
Purpose: High tibial osteotomy (HTO) has long been accepted as an effective treatment for
unicompartmental osteoarthritis of the knee in young, active adults. Traditionally, HTOs were
completed using a lateral closing wedge technique. However, in recent years medial opening
wedge HTO have become more popular. Over time, some HTOs fail and require conversion to
Total Knee Arthroplasty. The aim of this study was to compare the outcomes of total knee
arthroplasty in patients having previously undergone either medial opening wedge or lateral
closing wedge HTO.
Method: A review of our institutional database was conducted to identify all patients having
undergone a medial closing wedge HTO with subsequent conversion to total knee arthroplasty.
A total of 76 converted medial opening wedge HTOs were identified with mean follow-up of 59
months. We then extracted a matched cohort of 76 lateral closing wedge HTOs converted to
total knee arthroplasty with a mean follow-up of 71 months. The cohorts were matched for age
and year of surgery. SF-12, WOMAC, Knee Society Scores and survivorship at five years were
compared between the two groups. Statistical analysis was completed for each variable using
Independent Samples T-tests.
Results: No statistically significant difference was found in post-operative SF-12 scores
between lateral closing wedge HTO and medial opening wedge HTO groups (p = 0.63 for
Mental Component Scale and p = 0.93 for Physical Component Scale). Similarly, no
statistically significant differences were found in WOMAC or Knee Society Scores between the
two groups (p = 0.92 and p = 0.74 respectively). Finally, no statistically significant difference
was found in survivorship between the two groups at 5 years.
Conclusion: These results suggest that there is no difference in clinical outcomes of total
knee arthroplasty in patients having previously undergone medial opening wedge or lateral
closing wedge HTO.
22: Migration of hydroxyapatite-coated uncemented tibial components in a multi-center
RSA study
Elise Laende, NS; Allan Hennigar, NS; Glen Richardson, NS; Dermot Collopy, NS; Michael J
Dunbar, NS
Purpose: Uncemented total knee replacements have been purported to provide better longterm fixation in younger and more active patients. Surface coatings on uncemented tibial
components are often employed with the aim to enhance fixation, but the evaluation of such
interventions require in vivo testing. Evaluation with radiostereometric analysis (RSA) can
assess implant fixation in a small sample of patients in a much shorter time period than
conventional survivorship studies. The purpose of this multi-centre study was to use RSA to
evaluate the fixation of uncemented tibial components with a surface coating of hydroxyapatite
applied in a proprietary manner.
Method: Thirty-one patients were recruited in a consecutive sample survey of patients
undergoing total knee arthroplasty in Halifax, Canada (n=16) and Perth, Australia (n=15) using
the same inclusion/exclusion criteria and receiving the same uncemented implants
(Periapatite-coated Triathlon Total Knee, Stryker Orthopaedics) with the same surgical
approach. During surgery, eight tantalum markers, one millimetre in diameter, were inserted
into the proximal tibia. Using a calibration box, stereo RSA radiographs were taken postoperatively and then again at six weeks and three, six, 12 and 24 months following surgery.
Health status and functional outcome measures, including accelerometric gait analysis, were
recorded to quantify functional status of subjects before surgery and at each follow-up interval.
Results: The patients recruited at the two centers were of the same age group (66±6.2 years)
and weight (88±15 kg), but differed in height (Halifax: 168±9.2 cm, Perth: 178±8.3 cm; p value
= 0.004), BMI (Halifax: 31±4.7 kg/ m2, Perth: 27±2.9 kg/m2; p value = 0.005), and tibial
component size (Halifax: mean size 4, Perth: mean size 6). The Oxford Knee functional score
differed for the two centers pre-operatively (Halifax: 41±7.7, Perth: 31±7.6; p value = 0.003).
In Halifax there was one revision for aseptic loosening at 14 months. The migration of this
implant was 12.5 mm at 1 year. Excluding the revised case, the migration results at one year,
calculated as maximum total point motion (MTPM), were 1.31±1.25 mm for Halifax and
0.58±0.26 mm for Perth (p value =0.06). The clinical precision of the MTPM metric is 0.12 mm,
calculated as the standard deviation of measurements made from double exams of all patients.
Conclusion: The initial migrations in all but one patient are comparable with other
uncemented designs suggest general good initial fixation, but long-term monitoring of
migration will continue. The early revision in one patient suggests that the indications for
uncemented fixation still need refinement. Multi-center recruitment is valuable for obtaining a
diverse patient population and ensuring the success of an implant design across a more
representative global group.
23: No difference in health and activity-related quality-of-life outcomes after mobile and
fixed bearing medial unicompartmental knee replacement
Bas A Masri, BC; David J Biau, BC; Nelson V Greidanus, BC; Donald S Garbuz, BC
Purpose: Health and activity-related quality-of-life outcome differences between mobile and
fixed-bearing unicompartmental knee replacement have been poorly studied. We propose a
comparison of mobile versus fixed-bearing unicompartmental knee replacements. First we
hypothesized that health or activity-related quality-of-life outcomes would be similar between
both groups. Second, we sought for independent predictors of health or activity-related qualityof-life outcomes.
Method: Patients who underwent a medial UKR were identified from a prospectively collected
database. Demographic data, pre- and postoperative outcomes including the SF-12, WOMAC,
Oxford, self-administered patient satisfaction scale, and UCLA activity level score. Outcomes
were compared at baseline and last followup. Univariable and multivariable regression models
were used to seek for independent predictors of these outcomes.
Results: 104 knees (90 patients) with more than 2 year followup were identified, 37 with a
mobile bearing and 67 with a fixed bearing. At baseline, patients were comparable for sex,
height, and outcome measures. Patient in the mobile-bearing group were however significantly
younger and heavier than those in the fixed-bearing group. There was no statistical difference
at baseline between the mobile and fixed groups in the Oxford, WOMAC, and SF-12 (pcs and
mcs). At minimum 2 years followup, the groups differed statistically only in the postoperative
Oxford normalized score: the median Oxford-12 was 79 (Q1-Q3: 73-90) and 90 (Q1-Q3: 81-96)
in the mobile-bearing and fixed-bearing group respectively (P = 0.049). There was no other
statistically significant difference between both groups. The design of the component was
significantly associated with the SF-12 pcs at last followup: patients with a fixed-bearing design
had on average, after adjustment, a score 6 points inferior to those with a mobile-bearing (P =
0.024). There was no evidence of association between the design and the Oxford-12 (P =
0.43), the global WOMAC (P = 0.73), the SF-12 mcs (P = 0.95), the overall SAPSS (P = 0.47),
or the UCLA (P = 0.4). Scores at baseline were always predictive of scores at last followup.
Older patients were more likely to have lower SF-12 mcs (P<0.001) and UCLA (P<0.001);
patients with higher BMI were more likely to have lower WOMAC (P = 0.024); and women
were more likely to have lower UCLA (P = 0.0043).
Conclusion: There is no evidence for a significant effect of the bearing design after medial
unicompartmental knee replacement on health or activity-related quality-of-life outcomes.
Other demographic variables and baseline score values have, however, a determinant effect.
Given the absence of other proven long-term clinical benefits of the mobile-bearing design and
the inherent technical difficulties associated with this design, we recommend using fixedbearing unicompartmental knee implant for the treatment of anteromedial osteoarthritis.
24: Oxford Phase 3 Medial Unicompartmental Knee Arthroplasty: Clinical and
Radiographic Results of 463 knees at a Canadian Center
Rajesh Nair, BC; R Stephen J Burnett, BC; Duncan Jacks, BC; Christine Hall, BC; Megan
McAllister, BC
Purpose: Unicompartmental knee arthroplasty (UKA) is frequently performed in the treatment
of isolated medial compartment osteoarthritis (OA) in patients with anteromedial OA and an
intact ACL with favourable results. The results of this implant and technique have been
reported by the implant designers and by non-implant –design centers with different clinical
outcomes in the literature utilizing similar indications and surgical technique. A retrospective
study was undertaken at a Canadian center to assess the clinical and radiographic outcomes
of 463 consecutive Oxford Phase 3 mobile bearing medial UKA. This study is the largest nonimplant designer cohort reported to date.
Method: A retrospective review of 463 consecutive Oxford medial Phase 3 UKA’s (382
patients) was performed at a single Canadian tertiary care center over a 10-year period.
Patients were followed clinically and radiographically and no patients were lost to follow-up. All
patients were evaluated at most recent follow-up by an independent surgeon other than the
treating surgeon. Outcome measures included: Knee Society Clinical Rating Score (KSCRS),
Oxford Knee Score, WOMAC, SF-12, reasons for revision and reoperation, radiographs
including mechanical axis alignment, and patient satisfaction. A comprehensive statistical
analysis including predictors of failure and reoperation were performed by a statistician.
Results: The mean age at surgery was 69 years (range, 38-88). There were 218 women
(57%) and 164 men (43%). At a mean follow-up of 3.9 years (range, 0.1-8.3), the final
WOMAC score was 82, SF-12 physical score was 47 and mental score was 51. The overall
reoperation rate was 6.7% (31 knees). Twenty-three knees were revised to TKA at a mean of
35.6 months (range, 7-92) most commonly for progression to lateral compartment OA (10
knees). Eight knees were revised for tibial loosening, four for femoral loosening, and one for
PCL failure. Five further knees were deemed a failure and are pending revision to TKA for an
overall revision rate of 6.1% (28 knees). Three knees underwent polyethylene liner exchange
for bearing dislocation and two knees had further arthroscopic procedures. Improvements in
preoperative compared to postoperative scores for ROM KSCRS Pain and Function, and
Oxford Knee Scores were significant (p<.05). Overall 92% of the patients were extremely or
very satisfied with the outcome and 96% would have the procedure again.
Conclusion: UKA surgery with the medial Oxford Phase 3 implant is associated with high
patient satisfaction and a favourable revision rate at medium term. Progression to lateral
compartment OA was the most common reason for revision. Predictors of failure included: over
correction to a valgus mechanical axis, thickness of the polyethylene, and thickness of tibial
bone resection. The results of this study are similar to those reported by the implant designers
utilizing the same selection criteria and implant design.
25: The Addition of Antibiotics to Cement Does Not Appear to Lower the Risk of Early
Revision in Knee Replacement Surgery
Eric R Bohm, MB; Jing Gu, ON; Naisu Zhu, ON; Nicole De Guia, ON; Tammy Anderson, ON;
Claire Marie Fortin, ON; Michael J Dunbar, NS
Purpose: There exists considerable debate around the usefulness of adding antibiotics to
cement for the fixation of total knee replacement (TKR) implants. While antibiotics offer the
theoretical benefit of lowering the risk of early revision due to infection, no study has
definitively determined if this is true. Conversely, the addition of antibiotics may have an
unintended negative impact on the mechanical properties of the cement, and in fact result in a
higher revision rate. We sought to answer this question by examining data from both the
Canadian Joint Replacement Registry (CJRR), and the hospital morbidity database (HMDB)
which contains detailed information on all hospital stays in Canada.
Method: We identified 36 681 patients with the diagnosis of degenerative arthritis who had
their cemented primary TKR appropriately recorded in both CJRR and the HMBD (linkage rate
77%). The HMBD was then queried to ascertain if a revision had been performed in the 2
years following the primary TKR. If a revision was identified, the CJRR was queried for further
information on the exact reason for revision. In addition to the presence/absence of antibiotics
in the cement, other variables considered in the analysis included age, gender, comorbidities
(Charlson index), and the presence of diabetes.
Results: 16 665 patients had their TKR inserted using antiobiotic containing cement, while 20
016 patients had their TKR inserted without antibiotics in the cement. Revision occurred in 532
patients, representing an overall 2 year revision rate of 1.45%. This reflected a revision rate in
the antibiotic group of 1.51%, and in the non-antibiotic group of 1.40%, p=0.41. CJRR data on
the exact reason for revision was available for 206 of these 532 patients (38.7%). Twice as
many patients were recorded as being revised for aseptic loosening in the non antibiotic group
than the antibiotic group (p=0.02), however reported rates of revision for infection or pain of
unknown origin did not differ between the groups. When controlling for the presence of
diabetes, comorbidity index, age and gender, the hazard ratio of revision in the antibiotic
cement group was 1.066 [95% CI 0.90 – 1.27, p=0.46] compared to the non antibiotic group.
Conclusion: It appears that the addition of antibiotics to cement for TKR has no clinically
important effect on the risk of revision within 2 years of surgery. Longer follow up, as well as
confirmation of these findings with other national registries is warranted.
26: The Fate of the Remaining Knee(s) or Hip(s) in Osteoarthritic Patients Undergoing a
Primary TKR or THR
Steven JM MacDonald, ON; Douglas Naudie, ON; Richard McCalden, ON; James P
McAuley, ON; James L Howard, ON; Robert B Bourne, ON
Purpose: The natural history of osteoarthritis remains unclear due to its multifactorial etiology.
The long term influence of total joint replacement in one of the four large joints in lower limb to
the remaining unreplaced three has seldom been fully evaluated in osteoarthritic patients. We
seek to determine the incidence of a second total joint replacement after the initial THR or TKR
in a large, long-term cohort of patients, the pattern and the influence factors of a second
arthroplasty, and the yearly cumulative risk of undergoing a second replacement following the
first THR or TKR.
Method: A prospective total joint replacement database was employed to identify osteoarthritic
patients who received a primary hip or knee replacement with more than ten years follow-up.
This patient cohort was then followed to determine the information of a subsequent total knee
or hip replacement.
Results: Five thousand, three hundred and fifty two idiopathic osteoarthritic patients treated
with a total hip or knee replacement were followed a mean 17.8 ± 5.7 years. Forty six percent
(n=1341) of the 2917 initial total knee replacement patients underwent a contralateral
procedure, it was 30.5% (743/2435) in the hip site. The time interval between two successive
total joint replacements was shorter in the knee-to-knee group (3.05 ± 3.46 years) than in the
hip-to-hip group (4.60 ± 4.74 years). After the first total joint replacement, the contralateral
paired joint was the most likely joint to be replaced next, followed by the ipsilateral hip or knee
joint, then the contralateral unpaired one. Multivariate analysis revealed risk factors for needing
a second arthroplasty were higher body mass index and younger age in knees, and overweight
status in hips. Hazard analysis showed higher yearly cumulative risk of having a second
procedure following the first total knees as compared to total hips.
27: Two-stage revision total knee arthroplasty with an articulating spacer: Minimum
five-year review
Edward M Vasarhelyi, ON; James L Howard, ON; Douglas Naudie, ON; Richard McCalden,
ON; Steven JM MacDonald, ON
Purpose: The purpose of the current study is to review the minimum 5-year results of twostage revision total knee arthroplasty with articulating spacers for chronically infected total
knee arthroplasty, and secondarily, compare these outcomes with those performed with nonarticulating spacers.
Method: A total of 106 patients presenting to a tertiary care arthroplasty service with an
infected total knee arthroplasty that was deemed most appropriately treated with a two-stage
revision arthroplasty were prospectively enrolled. Patients were retrospectively reviewed based
on the type of spacer used during their first-stage revision; 60 patients were treated with
articulating spacers, while 46 were treated non-articulating spacers. Prospective data was
collected on each patient including demographic information, KSS, WOMAC and SF-12
scores. The scores were obtained prior to revision surgery as well as annually as part of their
standard follow up clinical review. In addition, data on need for subsequent surgery was
collected on each patient.
Results: The articulating and non-articulating spacer groups were well matched on age, BMI,
gender and side of surgery. There were statistically significant improvements in all components
of the KSS (p <0.001), WOMAC pain (p =0.02), stiffness (p=0.05) and function (p=0.001) when
comparing post-operative to pre-operative scores. There were no differences in the SF-12
mental component score and was a trend towards significance on the physical component
score. Survivorship of revision total knee arthroplasty that were initially treated with articulating
spacers at 5 years for all causes and aseptic loosening was 88.1% and 91.3% respectively.
When comparing articulating and static spacers, knees treated with articulating spacers
obtained an average range of motion of 100 degrees in comparison to 84 degrees for the static
spacers (p=0.009).
Conclusion: Two-stage revision arthroplasty with articulating spacers for chronically infected
total knee arthroplasty resulted in successful eradication of infection in 91.3% of patients at five
years. There were statistically significant improvements in post-operative KSS and WOMAC
scores with articulating spacers. The use of articulating spacers result in an improved range of
motion when compared to two-stage revision arthroplasty performed with static antibiotic
spacers.
28: Does Total Ankle Replacement Have an Affect on the Development of Peri-talar Joint
Arthritis?
28 - 0900
Does Total Ankle Replacement Have an Effect on the Development of Peri-talar Joint
Arthritis?
Steven JM MacDonald, ON; Josh Mayich, ON; Walter Mak, ON; Timothy Daniels, ON
Purpose: With the retained motion at the ankle in total ankle replacement (or TAR) it has been
theorized that the subsequent development of degenerative arthritis in the subtalar and
talonavicular joints would be significantly less than what is commonly seen post ankle fusion.
Although this has been commonly quoted as an advantage of TAR over fusion, it has not been
well substantiated. Furthermore, the method used to assess arthritis of the peritalar joints (or
PTJ), the Kellgren & Lawrence scale (or KLS), has never been validated for the PTJs. The
primary purpose of this study was to assess the progression of radiographic arthritis of the
PTJs. The secondary purpose was to assess the usefulness of the KLS for the measurement
of arthritis in the PTJs.
Method: 60 TAR were performed from 2001 to 2006, and have had a minimum of 5 years of
follow up. Pre-operative and post-operative radiographs of all patients were obtained. Of those
60 ankles, 43 did not have any ancillary surgery to fuse either of the PTJs at the time of the
initial TAR surgery. These patients were followed a minimum of 5 years. Three independent
reviewers analyzed all radiographs using the KLS for osteoarthritis. Interobserver analyses
were performed to analyze the consistency of measurement between observers.
Results: For the subtalar joint, mean pre-operative scores were 1.5+/- 0.5. Post-operatively
scores were 1.8 +/- 0.6. This represented an average advancement of arthritis of 0.3 grades.
For the talonavicular joint, the preoperative mean of 1.3 +/- 0.2 increased to 1.6 +/- 0.3
postoperatively. This represented an increase of 0.26 grades. Neither change represented a
statistically significant difference. (p = 0.97, and 0.45; respectively) Unfortunately, the KLS
showed very low inter-observer consistency. For the subtalar joint, a percentage agreement of
44% and K of 0.25 was shown. Somewhat more encouraging was the 78% agreement, and K
of 0.7 for measurement of the talonavicular joints.
Conclusion: The results of this preliminary research seem to show that in the post-TAR
setting, there is no significant development of arthritis of the peri-talar joints at five years. The
KLS; however, has been demonstrated to have questionable value in the measurement of
PTJ, specifically the subtalar joint.
29: A Finite-element Analysis Study of the First Metatarsophalangeal Joint of the Hallux
Rigidus
Presenter: Robert Flavin, IE, David FitzPatrick, IE; Michael Stephens, IE
Purpose: Hallux rigidus was first described in 1887. Many aetiological factors have been
postulated, including tight Achilles Tendon, Metatarsus Primus Elevatus and articular surface
mismatch, but none has been supported by scientific evidence.
Method: We have examined the static and dynamic imbalances in the first
metatarsophalangeal joint which we postulated could be the cause of this condition. We
performed a finite-element analysis (ABAQUS) study on eight male subjects and calculated a
mathematical model of the joint. Each model was defined in the elastic phase of the viscoelastic property of the model. Each model consisted of approximately 300,000 nodes and over
200,000 tetrahedral elements. The models were subjected to both normal and abnormal
physiological loads, including increased tensions (1); in the medial band of the plantar fascia,
(2); the long and short flexors and (3); simulated an articular surface mismatch.
Results: The results gave statistically significant evidence for an increase in tension of the
medial band of the plantar fascia as the cause of abnormal stress on the articular cartilage
rather than mismatch of the articular surfaces or subclinical muscle contractures. The graphical
representation of the stress on the metatarsal head showed over a 100% increase in the stress
on the cartilage of the metatarsal head with the increased stress primarily located over the
dorsal surface compared to physiological conditions, (7.3GPa vs 3.6GPa, p<0.05) The
increased tension in the Flexor Hallicus Brevis and Longus showed approximately 25%
increase in the stress on the cartilage of the metatarsal head however this increase was
distributed evenly through the FROM, (4.4GPa vs 3.6GPa, p>0.05). The simulated articular
surface mismatch demonstrated highly abnormal metatarsal head stresses on the first cycle
which resulted in a fracture.
Conclusion: Our study indicated a potential clinical cause of hallux rigidus and challenged the
many aetiological theories. It could influence the choice of surgical procedure for the treatment
of early grades of hallux rigidus. A postulated treatment is a cheilectomy with a dorsal Moberg
osteotomy to indirectly simulate a medial band plantar fascia lengthening procedure.
30: Anatomic Reduction of the Sydesmosis: What Values Can we Trust?
Jonah Hébert-Davies, QC; Marie-Lyne Nault, QC; G Yves Laflamme, QC; Stephane Leduc,
QC; Dominique M Rouleau, QC
Purpose: Anatomic reduction of the fibula with regards to the tibia has become the goal of
treating syndesmotic injuries. Several studies have recently questioned our capacity to do so,
implying that malreduction is much more common then originally thought. These studies focus
on post-operative CT scans to show wide-ranging variation. Our hypothesis is that there exists
a wide range of anatomical variation in the syndesmosis and this might lead to overly critical
opinion of post-reduction CT scans. The purpose of this study is to first identify radiological
measurements to evaluate the syndesmosis and establish normal values.
Method: Ankle CT scans of 100 normal ankles were evaluated. These scans had been done
to evaluate patients with foot trauma but without documented ankle trauma. A series of eight
measurements was then devised with some based on previously published studies and
modified by our group. These criteria measure both position of the fibula and rotation with
regards to the tibia. Two independent reviewers evaluated all scans and all measurements
were recorded initially and again at 6 weeks.
Results: We found that the most useful and reproducible measurement was rotation index, as
defined by the ratio of the posterior and anterior gaps between tibia and fibula. All results were
reproducible with excellent intra and inter-observer reliability with interclass correlations
between 0.8 and 0.99. On average we found that the fibula was 2mm (range 0-4mm) eccentric
posteriorly on axial CT-Scan views. Also, on average the fibula was externally rotated 10
degrees (range 3-13.)
Conclusion: Several studies have shown that reduction of the syndesmosis is essential to
restore normal ankle mechanics and prevent secondary degenerative changes. Our results
show that a significant amount of variability exists in the anatomical position of the
syndesmosis. The evaluation criteria developed in the study can give the surgeon a guideline
for evaluating post-operative reductions without having to scan a contralateral ankle.
31: COFAS Multicenter Study Comparing Total Ankle Arthroplasty and Ankle
Arthrodesis: Mid-Term Results
Timothy Daniels, ON; Mark A Glazebrook, NS; Alastair SE Younger, BC; Murray John
Penner, BC; Kevin J Wing, BC; Hubert Wong, BC; Peter Dryden, BC; Trish Francis, NS; Biraj
Bora, BC; Ellie Pinsker, ON
Purpose: Summary: A prospective, multicenter study compared the outcomes of 242 total
ankle arthroplasty (TAR) and 95 ankle arthrodesis (AA) patients at mean follow-up of 4.9
years. AOS and SF-36 PCS and MCS scores improved and were not significantly different
across the TAR and AA groups at final follow-up. Twenty-two patients (19 TAR, 3 AA)
underwent revision surgery. TAR is comparable to AA for the management of end-stage ankle
arthritis, with a higher revision rate in the TAR group. To present the mid-term results of a
prospective, multicenter total ankle arthroplasty and arthrodesis database.
Method: Between November 2001 and July 2007, patients were recruited by 4 surgical
centers across Canada and underwent either ankle arthroplasty (TAR) or ankle arthrodesis
(AA). Patient characteristics collected included demographics, comorbidities, and diagnoses.
Surgical data gathered included implant type, concurrent procedures, complications, and
revisions. The primary outcome measure was the Ankle Osteoarthritis Scale (AOS). Secondary
outcome measures were Short Form-36 (SF-36) scores and revision rates. Revision rates with
exchange or extraction of components as endpoint were calculated for TAR patients. For AA
patients, revision was defined as any surgery required to correct malunion, non-union, or
persistent symptoms, and amputation events. Linear mixed effects models were used to
compare the difference between the TAR and AA groups in AOS and SF-36 outcomes at final
follow-up, with adjustment for baseline characteristics.
Results: Of 372 patients enrolled in the study, complete records for 337 patients (90.5%) were
available for analysis. These included 242 TARs and 95 AAs with a mean follow-up of 4.9
years. The two groups were similar for sex (TAR: 53.2% male; AA: 60.9% male), BMI and
operated side. The TAR group was significantly older (62.8 ± 11.0 years; AA: 54.6 ± 11.6
years; p<0.001) and had a higher rate of inflammatory arthritis (p=0.001). Diabetes and
smoking during the 12 months prior to surgery were more prevalent in the AA group (p=0.05
and p=0.01, respectively). AOS and SF-36 scores improved in TAR and AA patients following
surgery (Table 1). Baseline AOS scores and SF-36 PCS scores were similar for the two
groups. Baseline SF-36 MCS scores were slightly lower in the AA group (p=0.03). After
adjustment for baseline characteristics and baseline AOS score, average AOS scores at final
follow-up were not significantly different across the two groups (1.7 units higher in the TAR
group; 95% CI: -4.6, 8.0). Similarly, after adjustment for baseline characteristics and baseline
SF-36 scores, average SF-36 PCS and MCS scores at final follow-up were not significantly
different across the TAR and AA cohorts (PCS: 1.1 units higher in the TAR group; 95% CI: 2.0, 4.3; MCS: .07 units lower in the TAR group; 95% -2.7, 2.6). Twenty-two patients
underwent revision surgery. Three AA patients required revision, all within the first 2 years
following surgery. A total of 19 TAR patients underwent revision, from 1 month to 7 years after
surgery.
Conclusion: This is the first longitudinal multi-centered clinical study comparing the
intermediate results of TAR to AA. Validated outcome scores indicate that TAR is comparable
to AA for the management of end-stage ankle arthritis with a higher revision rate in the TAR
group. Further work is required to identify the advantages and disadvantages of each
procedure.
32: Mechanical Adaptation and Density Distribution of the Subchondral Bone Plate After
Supramalleolar Osteotomies for Asymmetric Ankle Osteoarthritis
Christian Egloff, CH; Geert Pagenstert, CH; Victor Valderrabano, CH; Magdalena MüllerGerbl, CH
Purpose: Increasing evidence suggest that subchondral bone mineralization changes are
associated with progressive Osteoarthritis. Joint preserving surgery (JPS) revealed
encouraging results in reducing pain and improving subjective and objective function of
patients with asymmetric ankle degeneration. However, the biological effects and efficiency of
unloading surgery on the subchondral bone plate was not studied on molecular level, based on
density distribution. The purpose of this study was to evaluate and measure the density
distribution and mechanical adaptations of the subchondral bone plate of the distal tibia and
talus after supramalleolar osteotomies in patients with asymmetric ankle osteoarthritis using
CT-Osteoabsorptiometry (CT-OAM).
Method: We prospectively followed 14 consecutive patients between January 2006 and May
2008 with posttraumatic valgus ankle OA treated with supramalleolar osteotomy for JPS. We
included only patients younger than 65 years and with a follow up time longer than 12 month.
Of the remaining eight patients (six males, two females), all ankles (three right ankles, five left
ankles) were examined by a single slide CT scanner before and after JPS. The average follow
up time was 16 month, ranging from 13 to 24 months. The average age was 43 years, ranging
from 19 to 65. By means of CT-Osteoabsorptiometry (CT-OAM), the distribution of
mineralization on the subchondral bone plate of all distal tibiae and talus were analysed using
a standardized coordinate system with 15x20 gridlines to localize maximums of bone density
throughout the joint. All the left joint surfaces were point reflected so only right ankles were
analysed. Subchondral bone pixels were segmented and assigned to 10 density value groups
(Δ100 HU, range 200-1200 HU) using volume rendering technique (VRT).
Results: The subchondral mineralization distribution revealed considerable topographic
changes before and after JPS on the talar and less on the tibial articular surface. Areas of
greatest density in valgus ankle OA were found in the peripheral zones predominantly on the
lateral side. After JPS, regions of maximal density eased and a more evenly spared distribution
was observed.
Conclusion: Our results showed characteristic changes in mineralization distribution patterns
of the subchondral bone plate before and after JPS of posttraumatic valgus OA. We believe
these data can serve as a verification of the efficacy of JPS for patients with asymmetric ankle
OA.
33: Peroneal Tendons Plasty for Lateral Instability of the Ankle: A New Surgical
Technique
Roberto Somellera, MX; Peter A Schulz, DE; Hector Cabrera Palacios, DE; Michael Maru, UK
Purpose: The pronation and supination of the ankle joint gives the human a very unique
weight bear. This is shown in the ability for walking on uneven surfaces, climbing and dexterity
for performing sports. The stability of the ankle joint is not only provided by the anatomical
configuration of the tibia, fibula and talus within the mortise but by the combined function of
ligaments and muscles too. The chronic instability of the ankle precedes chronic pain, disability
for daily living activities and leisure sports. This is a direct consequence of ligamentous injuries
as well as elongation and dysfunction of the peroneal tendons. The main reason for surgical
reconstruction is chronic instability. The objectives of this study were to analyse the clinical
outcomes and complications of this new surgical technique and to compare the results with
other procedures described in the literature.
Method: We operated with this new technique in 83 patients, 15 were not included because
were lost for follow up. We included 67 patients in this study, 47 males, 20 females; 44 on the
right side and 23 on the left. The average age was 24 years ranging from 14 to 39.The
average age of follow up was 3 years ranging from 7 months to 10 yearsWe operated with this
new technique in 83 patients, 15 were not included because were lost for follow up. We
included 67 patients in this study, 47 males, 20 females; 44 on the right side and 23 on the left.
The average age was 24 years ranging from 14 to 39.The average age of follow up was 3
years ranging from 7 months to 10 years resultsWe operated with this new technique in 83
patients, 15 were not included because were lost for follow up. We included 67 patients in this
study, 47 males, 20 females; 44 on the right side and 23 on the left. The average age was 24
years ranging from 14 to 39.The average age of follow up was 3 years ranging from 7 months
to 10 years results.The surgical procedure starts with longitudinal incision of about 7 cms,
starting 4 cms above the tip of the lateral malleolus. The peroneous brevis and longus tendons
are identified. A incision over the tendinous part of bout tendons is performed at the same level
and 1 cm is excised from the substance of both tendons. The tendons are sutured again with a
Bunnel type suture. The wound is sutured by layers.
Results: We found excellent results in 88% of the patients, good in 12% and 0% bad results
according to the Sefton criteria (Sefton 1979). We had only one superficial infection and painful
nodules over the surgical area of the tendon in 25% of the patients after surgery. These
nodules disappeared after 6 months.
Conclusion: With exellent results in 88% of the patients, good in 12% and low rate of
complications this is a further surgical option for the treatment of lateral instability of the ankle
joint. This new technique provides a easier surgical approach, preserves better ankle anatomy
and biomechanics leading to a lower rate of complications.
34: The Importance of Plasma Sprayed Hydroxyapatite Coating on Titanium Plasma
Spray in the Osseointegration of Total Ankle Arthroplasty Implants
Presenter: Robert Flavin, IE; Mark Steeves, BC; Murray John Penner, BC; Alastair SE
Younger, BC
Purpose: The principle mode of failure of Total Ankle Arthroplasty (TAA) is aseptic loosening,
or failure of the prosthesis to bond to bone. This may be reflected in bone cyst formation,
subsidence, radiographic loosening, poor outcome scores secondary to pain, and revision for
aseptic loosening. We hypothesize that the revision rates for a non Hydroxyapatite coated
sintered titanium bead ingrowth prosthesis may be higher than a porous coated surface with
plasma sprayed titanium and hydroxyapatite flat backed prostheses. Both were mobile bearing
in design. In this study we endeavoured to determine if this was a chance observation, or
whether a higher revision rate truly existed.
Method: We performed a retrospective study comparing the early failure to osseointegrate rate
of two popularly used Total Ankle Arthroplasty prostheses, Hintegra (Newdeal SA, Lyon,
France) and the Mobility (Depuy International, Leeds, UK). Exclusion criteria were revisions
due to infection. Tribological factors, for each patient, for aseptic loosening were standardized
to isolate the effect of the different bone – implant geometries and surface coatings.
Results: Between 2005 and 2007, thirty-three Mobility TAAs were performed and between
2007 and 2010 thirty-seven Hintegra TAAs were performed. The baseline demographics
showed no statistical difference (p-value >0.05). This study demonstrated statistically
significant higher revision rates (15.2% vs 2.7%; p-value=0.0477) component loosening rates
(as diagnosed by comment at explanation at the revision surgery), clinically and
radiographically by SPECT-CT (25.7% vs 5.4%; p-value=0.0095) and symptomatic
impingement rates, as diagnosed clinically and radiographically on SPECT-CT (27.2% vs
8.1%; p-value=0.0275).
Conclusion: In conclusion, by examining the early osseointegration failure rates of two
popularly used Total Ankle Arthroplasty prostheses by isolating the effects of the different bone
– implant geometries and surface coatings; we demonstrated a statistically significant failure to
osseointegrate in the Mobility TAA group which may be due to either geometry or surface
coating.
35: Is Valgus Deformity Greater than Ten Degrees at the Ankle Really a Contraindication
to Total Ankle Arthroplasty?
Timothy R Daniels, ON; Josh Mayich, ON; Ellie Pinsker, ON
Purpose: Total ankle arthroplasty (or TAR) in the setting of coronal deformity is controversial.
Historically, coronal deformity over 10 degrees was thought to be a contraindication; however,
more recent literature has shown that acceptable outcomes can be achieved. Although varus
deformity has been studied, clinical information on the outcomes associated with valgus
deformity are lacking. The purpose of this prospective cohort study was to evaluate
survivorship of TAR components in the setting of preoperative valgus coronal deformity. A
matched cohort of TAR performed in ankles with no coronal deformity was used for
comparison.
Method: Between 2001 and 2009 consecutive patients with valgus deformity greater than 10
degrees who were willing to undergo TAR were enrolled. A minimum of two-year follow-up was
required. A primary outcome of revision of the metal components was selected. Secondary
outcomes including re-operation and patient outcome scores, as well as radiographic and
clinical data were also collected.
Results: 31 TAR in 29 patients met the inclusion criteria. The two-year failure or metal
component revision rate was 12.90%. (95% confidence interval [CI] 3.63%–29.83%). The twoyear reoperation rate, which included any operation on the operated foot and ankle that was
not a metal component revision, was 9.7% (95% confidence interval [CI] 2.56%–25.7%), with
three patients requiring reoperation. This compared unfavourably to the control population.
(Revision rate, reoperative rate) The AOS Pain Component decreased by an average of 27.7 ±
23.2 points in the valgus group and 34.7 ± 21.9 in the neutral group (p<0.01). There was no
statistical difference in pain improvement between the two groups (p=0.793). The AOS
Disability Component decreased by an average of 40.7 ± 18.6 points in the varus group and
38.0 ± 23.8 in the neutral group (p<0.01). There was no statistical difference in pain
improvement between the two groups (p = 0.578).
Conclusion: Although clinical results from TAR in the setting of valgus can be quite good, the
failure rate of TAR in this setting is relatively high. Caution should be used when attempting
TAR in valgus deformity, and patients should be counseled appropriately before proceeding.
36: Total Ankle Arthroplasty in the Diabetic Population - Results of a Matched Casecontrol Study using a Prospective Data-base
Ines LH Reichert, UK; Ellie Pinsker, ON; Ryan Khan, ON; Timothy R Daniels, ON
Purpose: Diabetes mellitus in patients with end-stage ankle arthritis does present the
physician with the question if ankle replacement surgery in diabetic patients is associated with
higher risk and worse outcome than in the non-diabetic population.
Method: At our institution pre-and postoperative data for all patients who undergo ankle
replacement is collected prospectively since 2002. We have retrieved the details of all patients
with Diabetes Type 2 operated during this time period. Clinic notes and drug charts were
examined for evidence of problems with post-operative wound healing, infection or revision
and their prospective collected outcome data (AFOAS, SF36) was analysed. Each patient in
this cohort was closely matched with a non-diabetic patient taking in account age, gender, type
of ankle arthroplasty, aetiology of arthritis and severity of pre-operative ankle deformity
(COFAS) and BMI. The ASA, blood sugar, medication and smoking habit were also noted.
Results: There were 26 ankle replacements in each group, 24 diabetic (D) and 25 nondiabetic (ND) patients: mean age 65.6 (D), 64.2 (ND); mean BMI 29.4 (D), 30.0 (ND); aetiology
of arthritis: RhA (3 D, 3 ND), post traumatic (14 D, 18 ND), OA (9 D, 5 ND); COFAS I (2 D, 2
ND), COFAS II (6 D, 8 ND), COFAS III (5 D, 3 ND), COFAS IV (13 D, 13 ND); type of prothesis
STAR (9 D, 10 ND), Mobility (6 D, 6 ND), Hintegra (11 D, 10 ND). The mean follow-up was 3.8
years with a minimum of two years. In all diabetic patients significant peripheral neuropathy or
vascular disease had been excluded pre-operatively. The records detailing post-operative
clinic follow-up were complete. Five patients in the diabetic and nine patients in the nondiabetic group had wound healing problems, which ranged from mild erythema (2 D, 2 ND),
minor stitch abscess (2 D, 1ND), partial dehiscence treated with repeated office debridement
for 2-5 months (5 ND) to application of VAC pump (1 ND) and operative debridement (1 D).
Re-operation: in the diabetic group two STAR protheses required revision / arthrodesis for
catastrophic loosening, 1 Hintegra was revised for pain. One diabetic patient suffered from a
chronic pain syndrome prior to surgery and a BKA was performed in spite of a stable prothesis.
In the non-diabetic group 2 STAR and 1 Hintegra were revised for loosening and 1 Hintegra
(ND) required arthrodesis for late deep infection at two years post surgery. The functional
outcome data suggests significant improvement for the AOFAS score for pain and disability for
the non-diabetic group but less improvement for the diabetic group.
Conclusion: Our study does not confirm an increased risk of infection or revision for the
diabetic patient undergoing ankle arthroplasty, when significant peripheral neuropathy has
been excluded pre-operatively. However, our results might indicate less improvement in
functional outcome for diabetic than for non-diabetic patients, matched for BMI and severity of
ankle arthritis. More detailed analysis and larger studies are required.
37: Wound Complication and Infection Rate in Clean First-time Elective Foot and Ankle
Surgery - A Retrospective Review
Martin Wiewiorski, CH; Thomas Voellmy, CH; Victor Valderrabano, CH
Purpose: The aim of this study was to evaluate the rate of wound complications and infection
in patients undergoing clean elective first-time surgery of the foot and ankle joint.
Method: A retrospective chart review of 298 patients who received elective foot and ankle
surgeries between 2006 and 2010 at one hospital clinic was performed. Only those patients
who were having elective foot or ankle surgery for the first time, were being followed up at the
hospital’s outpatient clinic, had a nontraumatic cause for their surgery and no history of
previous infection were included in this study. All surgeries were performed by the senior
author. A wound complication was defined as a superficial dehiscence, edema, erythema, or
stitch abscess. A wound was considered infected when purulent material from the wound sites
was noted and an organism(s) was cultured. All patients received a preoperative antibiotic.
Results: In 46 patients (15.4 %) a wound complications was noted. In four patients (1.3%) a
wound complication was encountered. Chi square tests and logistic regression models were
performed to determine if age, sex, length of stay, type of surgery, surgery time, tourniquet
use, antibiotic application time, diabetes mellitus, rheumatoid arthritis and internal fixation were
predictive of or associated with postoperative wound infection or complication. Of those
factors only rheumatoid arthritis was significantly associated with wound infection (p=0.01,
relative risk 20.08). After adjustment of the factors age, surgery time, diabetes and type of
surgery only age and surgery time showed a significant association with wound complications
(p≤0.001).
Conclusion: The results suggest that higher age and prolonged surgery time are the major
factors for wound complications in routine elective foot and ankle surgery.
38: A Retrieval Analysis of High Flexion Versus Posterior Stabilized Tibial Inserts
Douglas Naudie, ON; Nicholas Paterson, ON; Matthew Teeter, ON; Steven JM MacDonald,
ON; Richard McCalden, ON
Purpose: High-flexion total knee replacements have recently been introduced to increase
range of motion and patient satisfaction, but have not yet been studied in a retrieval analysis in
comparison to standard posterior-stabilized tibial inserts. The purpose of the present study was
to examine how the design changes between high-flexion and posterior-stabilized tibial inserts
would affect their (1) overall damage profile and more specifically the damage on their (2)
articular surface, (3) backside and (4) tibial post.
Method: We matched 20 retrieved high-flexion inserts to a cohort of 20 posterior-stabilized
inserts from the same manufacturer on the basis of duration of implantation, body mass index,
and age. Inserts were divided into 16 zones and a microscopic analysis of surface damage
was carried out. Several inserts were scanned using micro-CT to further quantify instances of
severe post notching.
Results: Significantly greater backside (p = 0.01) and post (p = 0.02) damage were found in
the high-flexion group, with no significant difference in the articular surface (p = 0.70) or overall
(p = 0.18) damage scores. Post notch depths in both high-flexion and posterior-stabilized
groups ranged from 0.6 to 1.9 mm.
Conclusion: Increased post damage in the high-flexion group suggests a potential
susceptibility to post fracture, particularly at higher degrees of flexion where contact stresses
are higher. The increased backside damage was unexpected as the two groups have the
same tibial component, locking mechanism, and sterilization method. The introduction of a
highly crosslinked high-flexion insert will require close scrutiny as a result of the increased
strain and potential for post damage demonstrated in this series.
39: Biomechanical effect of Patellar Tendon Recession for Exposures in Knee
Arthroplasty
Milton Parai, ON; Hakim Louati, ON; Andrew Spiers, ON; Phillippe Poitras, ON; Hani Zamil,
ON; Geoffrey Dervin, ON
Purpose: Standard medial arthrotomy for total knee exposure may not provide adequate
exposure in complex primary and revision surgeries. Release of a portion of the patellar
tendon insertion has been compared to osteotomy of the tubercle with comparable results.
Specific limits of release and how it affects exposure and strength compared to a native tendon
have not yet been defined. Our purpose is to study the effect of partial recession of the patellar
tendon and its effect on strength compared to control groups.
Method: Paired fresh and single cycle freeze-thawed cadavers were obtained. The test knee
was fixed at 90 degrees of flexion and exposed using a standard medial arthrotomy. The
insertion of the patellar tendon was identified and 50% of its proximal width was recessed with
a taper to an intact inferomedial apex. The knees underwent tensile cyclic loading and load to
failure, using a biomechanical axial torsional testing system. Peak load (N) at load to failure
was measured. Data was tabulated using a computer spreadsheet program.
Results: Eight pairs were obtained to date. Two were unsuitable to test due major structural
and degenerative changes. The average decrease in strength was 16% (+/-18%) with range
61-108%. Average load to failure was 3113 N (+/- 1055) in the recession group and 3038 N
(+/- 1479) in the control. Median load to failure was 2936 N and 2968 N, respectively.
Conclusion: The effect of lowering the insertion strength of the patellar tendon by partial
recession was not consistently observed. Though it has been shown to be an acceptable
alternative to osteotomy, our study suggests that some strength reduction may occur. This may
be an acceptable risk compared to catastrophic failure due to excess tension. Other variables
that may affect its strength include the quality of bone and the extent of degenerative disease.
Judicious use of this technique could be an acceptable strategy to improve exposure while
minimizing excessive and potentially hazardous retraction.
40: Prospective Study On Functional Outcome Of Arthroscopic Drilling Combined With
Intra Articular Stem Cell- Hyaluronic Acid Injections Compared To Intra Articular Stem
Cell- Hyaluronic Acid Injections Alone Without Arthroscopic Drilling For Treatment Of
Ost
Ahmed AbdulAmeer Alkhuzai, IQ
Purpose: Background: Osteoarthritc knee patients’ grades 2, 3 with disadvantages from the
treatments by Hyaluronic acid injection with oral glucosamine-chondroitin were treated by
arthroscopic drilling combined with intraarticular injections of Stem Cell-Hyaluronic acid. Aim
of study: We studied the effectiveness of combination arthroscopic drilling plus post operative
intra articular injection of Stem cell- Hyaluronic acid with oral glucosamine-chondroitin sulfate
compared to intra articular injection of Stem cell- Hyaluronic acid with oral glucosaminechondroitin alone without arthroscopic drilling in treatment of grade 2, 3 knee osteoarthritis.
Method: In prospective comparative study 32 patients with knee osteoarthritis grade2, 3
disadvantages treated by intraarticular injections Hyaluronic acid plus oral glucosaminechondroitin were randomized according to inclusion exclusion criteria into two groups. Group A
16 patients were treated by arthroscopic drilling with intra-articular injections of stem cell
(harvested from patients bone marrow then expanded the cell number), with Hyaluronic acid
25 mg plus oral combination of glucosamine-chondroitin sulfate, the injections done post
operative. Compared to group B 16 patients were treated by intra-articular injection of stem
cell-Hyaluronic acid 25 mg plus oral combination glucosamine-chondroitin alone without
arthroscopic drilling, the patients were followed up for 24 months period. The primary outcome
measurements were according to Modified Lequesne's and Modified WOMAC scores.
Results: In both groups, A and B significant reduction in the mean of both Modified
Lequesne's and Modified WOMAC scores from baseline were seen at all follow up visit for 12,
24 months. Also there were significant statistical differences and clinical improvements at 12,
24 months for both Modified Lequesne's and Modified WOMAC scores in group A superior to
the group B (P-value < 0.0001). No severe adverse events related to these combinations were
observed.
Conclusion: We concluded that arthroscopic drilling with post operative intra-articular
injections of stem cell-Hyaluronic acid plus oral combinations of glucosamine-chondroitin
sulfate depending on Modified Lequesne's and Modified WOMAC scores for 2 years follow up
are superior to intra-articular injections of Stem cell- Hyaluronic acid combined to oral
glucosamine-chondroitin alone without arthroscopic drilling.
41: The Effect of Tibial Component Overhang on Medial Collateral Ligament Loads: An
In Vitro Robotic Study
Ravindra Gudena, UK; Mohammad Atarod, AB; Jason Werle, AB; Cyril Frank, AB; Nigel
Shrive, AB
Purpose: Tibial implant overhang has been identified as a possible problem in
unicompartmental knee replacements (UKR) and to some degree in total knee replacements
(TKR). Overhang on the medial side can cause irritation of soft tissues and medial collateral
ligament (MCL) impingement. We conducted an in-vitro robotic study to assess the load
changes in MCL during passive flexion-extension (PFE) with different amounts of overhang, to
define a safe overhang limit. We also investigated the relationship between flexion angle and
load changes in the MCL.
Method: Six fresh frozen human cadaveric knees were used in this study. The PFE motion
was applied to each joint and recorded using a kinematic linkage. The joint was then mounted
on a unique 6-DOF parallel robot(R-2000, PRSCo, Hampton, NH, USA, 0.05 mm accuracy)
and the previously-recorded PFE was reproduced. All tissues except MCL were removed and
the PFE was repeated for 30 cycles while the loads in MCL were recorded simultaneously
using a force-moment sensor. Using a coordinate measuring machine, 2mm, 4mm and 6mm
overhang placements were marked and the tibial component was successively implanted in
the respective positions. For each overhang, the PFE was repeated for 30 cycles and MCL
loads recorded. A two-way ANOVA was performed to detect statistically significant effects of
overhang and flexion angle on the MCL load.
Results: There was no statistically significant load changes in the MCL with 2mm overhang
(P=0.15). However, there were statistically significant differences in MCL loads with 4mm and
6mm overhang placements (P=0.036 and P=0.045, respectively). The loads were almost
doubled from 2mm to 4mm of overhang. The peak baseline (no overhang) MCL loads found at
90 degrees of flexion in three joints, and in extension in the remaining three, depending on the
PFE recorded for each specific joint. This trend was followed even with the overhang. There
was no positive correlation between load changes in the MCL and joint flexion angle
(P=0.262).
Conclusion: Tibial components are available in incremental sizes. In all UKR and TKR
systems, undersizing the tibial tray will transfer loads through weak cancellous bone rather
than the stronger cortical bone. In this case, using larger implants with an overhang of less
than 2mm will avoid the risk of tibial component subsidence. This is the first biomechanical
study to investigate the relationship between tibial component overhang and corresponding
MCL loads. Our study findings support the previously published retrospective clinical study that
indicates no change in UKR outcome scores with tibial implant overhang less than 3mm. We
recommend from our study that if the component overhang is greater than 2mm in a
symptomatic patient, one should consider revision of the tibial component. Results of this study
can also be attributed to the collateral ligaments impingement with osteophytes in an arthritic
knee.
42: Two Year Migration in a Randomised Controlled Trial of Fixation with or without
Screws for an Uncemented Tibial Base Plate
Allan Hennigar, NS; Elise Laende, NS; Michael Gross, NS; Michael J Dunbar, NS
Purpose: The option of screw fixation for the uncemented Advance BioFoam Knee
Arthroplasty tibial components is available to surgeons, but it is unclear if this augmentation is
necessary to achieve stable fixation. The foam metal backed tibial components utilize a porous
titanium coating on the underside of the tibial baseplate, intended to promote bone in-growth
and provide a more robust bone-implant interface without cement. The addition of up to four
titanium screws is also possible. The purpose of this study was to employ radiostereometric
analysis (RSA) to compare implant migration in a randomized controlled trial of this implant
design with or without screw fixation over two years.
Method: Fifty-one patients were randomized to receive a BioFoam total knee replacement
(Wright Medical) with or without screw fixaiton. During surgery, eight tantalum markers, one
millimetre in diameter, were inserted into the proximal tibia. RSA radiographs were taken postoperatively and at six weeks and three, six, 12 and 24 months following surgery using dual xray heads and an RSA calibration box. Health status and functional outcome measures were
recorded to quantify functional status of subjects before surgery and at each follow-up interval.
Results: The migration results at two years, calculated as maximum total point motion
(MTPM), were 1.40±1.09 mm for with screw fixation and 1.28±0.84 mm without screw fixation
(p value =0.821). The clinical precision of the MTPM metric is 0.33 mm, calculated as the
standard deviation of measurements made from double exams of all patients.
Conclusion: The migration results at two years indicate that the addition of screws does not
significantly impact implant fixation and both designs are considered to display patterns of
stable fixation. Although higher than the migration seen with cemented tibial components, the
amount of migration is comparable to other uncemented designs.
43: Biomechanical and Neuromuscular Changes after Total Knee Arthroplasty are SexSpecific
Janie L Astephen Wilson, NS; Cheryl L Hubley-Kozey, NS; Michael J Dunbar, NS
Purpose: Females with moderate knee osteoarthritis (OA) walk with different movement and
loading patterns than their male counterparts (McKean et al., 2007). Despite the recent
emergence of gender-specific prostheses, there has been little research into the differences in
the post-TKA response of the locomotor and neuromuscular systems between sexes. The
objective of this study was to examine to the sex-associated differences in the patterns of knee
kinematics, knee kinetics and neuromuscular control of knee muscles before and after TKA
surgery.
Method: Sixty-four (36 female, 28 male) individuals with end-stage knee OA underwent gait
and electromyography (EMG) testing within a week prior to TKA and one year following
surgery. 3D knee joint angles and net external moments were calculated over the gait cycle.
EMG of 3 quadriceps, 2 gastrocnemius and 2 hamstrings muscles was recorded. Principal
Component Analysis (PCA) was used to extract major patterns of the knee angles, moments
and muscle groups. Three-factor ANOVA was used to test for differences in these patterns
between sexes, visits (pre and post) and muscle (p < 0.10).
Results: Post-TKA, females had a more constant knee adduction moment pattern during
stance than males (PC2, p = 0.06). A sex by visit interaction in the knee flexion moment (p =
0.06) indicated that females shifted to a later peak extension moment in late stance and males
to an earlier peak after TKA. The overall magnitude of knee adduction angles during gait
reduced post-TKA for both groups (PC1, p = 0.05), but the effect was greater in females. The
rotation angle in late stance became more internally rotated in females and more externally
rotated in males post-TKA (PC3, p = 0.02). Female overall gastrocnemius EMG magnitudes
became higher post-TKA, male magnitudes became lower (PC1, p = 0.036). Females also had
later peak gastrocnemius activity in stance than males (PC2, p = 0.01). Females had higher
overall magnitudes of quadriceps activity in stance (PC1, p = 0.013) and more continued
activation of the quadriceps muscles during stance than males (PC3, p = 0.05). This continued
activation of the quadriceps became more pronounced in females post-TKA and less so for
males (p = 0.05).
Conclusion: While patterns of knee and muscle function during gait have been shown to
move toward asymptomatic patterns post-TKA (Hatfield et al., 2011; Hubley-Kozey et al.,
2010), these results suggest that pattern changes are sex-specific, with male patterns seeming
to move closer to more functional, asymptomatic patterns than females. This has implications
for sex-specific surgical decision-making, implant design and post-TKA rehabilitation efforts.
44: Pre-Total Knee Arthroplasty Gait Analysis Predicts Post-Operative Changes in
Function and Joint Loading
Michael J Dunbar, NS; Gillian Hatfield Murdock, NS; Cheryl Hubley-Kozey, NS
Purpose: The demand for total knee arthroplasty (TKA) surgery is increasing dramatically, but
it is expected that the present human resources will be unable to keep up with the demand in
the near future. Hence we need to develop objective models to determine who will benefit most
from TKA in order to effectively manage waitlists. This study determined if changes in pain,
function and joint loading could be predicted using pre-TKA biomechanics and muscle
activation patterns during walking.
Method: 57 participants with severe medial knee OA were tested within one week prior to TKA
and approximately one year later. Participants completed the WOMAC questionnaire at each
testing session (subjective measures of pain and function). Three-dimensional knee angles
and moments and electromyograms from seven lower extremity muscles were recorded during
gait. Gait data were analyzed using Principal Component Analysis (PCA). Self-selected gait
speed and the overall knee adduction moment magnitude (PC1) were used as objective
measures of function and medial compartment loading, respectively. Regression analysis
determined what pre-TKA gait measures predicted the change in post-TKA subjective and
objective outcome measures.
Results: A phase shift in early stance activity (PC3) for the vastus medialis waveform
explained 12.0% (p>0.05) and 13.7% (p<0.05) of the variance in the change post-TKA in
WOMAC pain and function scores, respectively. Participants not displaying the phase shift had
greater improvements in self-reported pain and function. Prolonged stance phase activity
(PC2) for the lateral hamstrings explained 23.6% of the variance in the change in gait velocity
(p<0.001). Participants with prolonged hamstrings activity pre-TKA had greater improvements
in gait speed post-TKA. The pre-TKA score for the overall magnitude of the medial
compartment load (PC1 for the knee adduction moment) was the best predictor for the change
in this variable post-TKA. 62.7% of the variance was explained by the pre-TKA PC1 score
(p<0.001), with an additional 4.8% of the variance being explained by the overall amplitude of
activity (PC1) for rectus femoris (p<0.05). Higher pre-TKA knee adduction moment magnitude
and rectus femoris activation were associated with greater post-TKA decreases in the knee
adduction moment overall magnitude.
Conclusion: While pre-TKA biomechanics and muscle activation patterns were poor
predictors of changes in self-reported outcome measures, they did predict large proportions of
variance in objective measures of function and loading. More altered muscle activation
patterns and higher medial compartment loading pre-TKA, indicative of poorer pre-TKA gait
patterns, were associated with greater improvements in gait speed and greater decreases in
medial compartment loading. These findings have implications for managing TKA waitlists and
illustrate the difference between subjective and objective outcomes.
45: The Association of Bone Microarchitecture with Total Knee Implant Stability
Jen Hurry, NS; Allan Hennigar, NS; Elise Laende, NS; Michael J Dunbar, NS
Purpose: Currently, orthopaedic surgeons have no method to detect or monitor arthroplasty
component loosening, or predict which implants will fail. Radiostereometric Analysis (RSA) has
proven sensitivity in determining relative movement between implants and underlying bone
with high precision. The purpose of this pilot study is to determine if there is an association
between bone mineral density (BMD) and bone microarchitecture in the proximal tibia and
implant migration as measured with RSA.
Method: Ten patients were followed prospectively for 1-2 years with RSA and with Dual-enery
X-ray Absorptiometry (DXA) BMD scans using a GE Lunar Prodigy fan-beam densitometer.
The BMD of five regions of interest in the proximal tibia were measured preoperatively, and at
1 and 2 years postoperatively. RSA exams were taken immediately postoperatively and at 1
and 2 years, with the same radiographs used for microarchitecture analysis. X-rays in these
exams were captured with high-resolution Canon digital detectors (CXDI-55). Linear regression
analysis was used to examine associations between BMD, microarchitecture and implant
migration.
Results: BMD change over time in the medial compartment has a moderately negative
association with proximal translation (r squared = -0.57) and a positive association with
maximum total point motion (r squared = 0.78). When adding a microarchitecture parameter
from different regions of the periprosthetic tibia to the change in BMD, the amount of variation
in proximal translation that is explained rises dramatically (r squared = 0.81 to 0.99). In one
region of interest the microarchitecture parameter alone showed a significant relationship with
internal rotation of the implant (r squared = 0.8) while no correlation with BMD was found. All p
values were less than 0.05.
Conclusion: Our results show that incorporating bone microarchitecture parameters in the
quantitative analysis of high-resolution radiographs explains more of the variation in implant
motion than can be explained when using BMD change alone. This pilot study reveals the
potential of measures of bone microarchitecture for enhancing BMD assessment and as a
potential surrogate indicator for implant stability.
46: The Effect of Total Knee Arthroplasty on Hip and Ankle Joint Mechanics
Janie L Astephen Wilson, NS; Kathryn Young, NS; Cheryl L Hubley-Kozey, NS; Michael J
Dunbar, NS
Purpose: Abnormal knee function as a result of severe osteoarthritis has been well
characterized. After total knee arthroplasty (TKA) surgery, comparison of knee mechanics to
the pre-operative state is often used to assess surgical success. Less well acknowledged are
the compensatory changes in hip and ankle joint mechanics that accompany severe knee
osteoarthritis (Astephen et al, 2008), and post-TKA functional assessments rarely consider the
surgery’s effect on the mechanics of these joints. The purpose of this study was to characterize
the changes in joint angle patterns at the hip and ankle after TKA surgery.
Method: Three-dimensional lower extremity kinematics were captured during gait for 60
asymptomatic subjects and 64 patients scheduled to receive a TKA surgery. Sagittal plane hip
and ankle angles were represented as waveform patterns over the gait cycle. Principal
component analysis (PCA) was applied to each angle (hip and ankle separately) to extract the
major modes of variability in the data (Deluzio and Astephen, 2007). Paired t-tests were used
to compare post-TKA angle patterns to the pre-TKA state and ANOVA was used to compare
both to asymptomatics.
Results: The first 3 principal components for hip and ankle sagittal plane flexion angles
explained 92% and 87% of the variability cumulatively, respectively. The overall magnitude of
hip flexion during gait (PC1) was lower than asymptomatic pre-TKA and remained lower postTKA, (P=0.037), indicating that hip flexion magnitude was not restored postoperatively. The
relative difference (i.e. range) between late stance hip extension and swing phase flexion
(PC2) increased from pre-TKA to post-TKA (P=0.001), yet still remained lower than
asymptomatic values post-TKA (P<0.001). PC2 of ankle flexion captured the
plantar/dorsiflexion range of motion throughout gait. There were no changes in PC2 from pre
to post-TKA, and patients exhibited less angular range compared to the asymptomatic group
(P<0.001). PC3 characterized later peak plantar and peak dorsiflexion angles in the gait cycle,
and there were significant differences between pre and post-TKA (P=0.006), but no difference
from asymptomatic post operatively (P=0.34).
Conclusion: This study showed some improvements in sagittal plane hip and ankle angle
patterns one year after-TKA surgery. However, some compensatory changes in hip and ankle
mechanics that were associated with severe OA pre-TKA were maintained post-TKA. This
suggests that while TKA surgery improves joint function in the lower extremity, some abnormal
patterns persist that may be indicative of an unfavourable mechanical environment. Post-TKA
outcome should therefore objectively assess entire lower extremity function, and
implant/surgical design should aim to optimize entire lower extremity function.
47: A Murine Model of Early Onset Scoliosis
Michael B Sullivan, QC; Ali Esmaeel, QC; Marco Kneifel, BC; Jean Ouellet, QC; Janet E
Henderson, QC; Neil Saran, QC
Purpose: Scoliosis can be infantile or juvenile in onset; however, it is more frequently
identified in adolescent children, particularly girls as they enter puberty. Untreated scoliosis
progresses with age and there are currently no effective nonoperative therapies to prevent this
progression. Furthermore, current animal models are surgically induced and tend to use large
animals: a characteristic that would preclude pre-clinical pharmaceutical therapeutic research.
We have noticed that FGFR3-/- mice, in addition to severe kyphosis and other skeletal
abnormalities, develop progressive scoliosis until end of life and may be a viable model of
scoliosis.
Method: Forty-seven FGFR3-/- and forty-four wildtype mice of a C3H background were
radiographed between one and nine times with posterior-anterior and lateral views to measure
kyphotic and scoliotic Cobb angles. Mice were euthanized at ages ranging from 4 to 25 weeks
and processed for histology and high resolution micro-computed tomography (micro-CT) to
compare parameters such as vertebral and inter-vertebral disc (IVD) morphology, micro
architecture, vertebral rotation, and cellular activity. Knockout mice were paired with an age
and gender matched wildtype counterpart for micro-CT and histological analysis to ensure that
scoliotic apical vertebrae were compared to the equivalent wildtype vertebrae.
Results: FGFR3-/- mice developed scoliosis by 8 weeks (p<0.05) and scoliosis progressed
until the end of study, reaching a maximum of 40.9o±18.3 compared to wild-type counterpart of
5.1o±4.2. The present model has 98% incidence (≥10o) by skeletal maturity, though location
and severity are varied. Micro-CT analysis of knockout vertebral body micro architecture
revealed decreased Bone Volume Fraction (BV/TV) of the convex side and decreased IVD
thickness on the concave side of the curve. Vertebral body height was greater on both
concave and convex sides, with convex being comparatively greater. Histological analysis of
bone mineralization and cartilage support micro-CT data, and indicates concave IVD
compression and nucleus pulposus translation towards the convex side.
Conclusion: FGFR3-/- mice developed a high incidence of progressive scoliosis prior to
skeletal maturity. Results reveal that a characteristic scoliosis develops with respect to
vertebral wedging, intervertebral disc wedging and osteopenia. Because the proposed model
features spontaneously occurring scoliosis, we see it as more useful model than ones that are
surgically induced. FGFR3-/- mice are an improved animal model that are inexpensive, easily
available, non-invasive, and closely reproduce the disease and should be used for future
development of non-surgical treatments of scoliosis.
48: Correlations between Quantitative MRI and Mechanical Parameters of Human
Intervertebral Discs with Different Grades of Degeneration
John Antoniou, QC; Laura M Epure, QC; Arthur Michalek, VT; James C Iatridis, NY; Fackson
Mwale, QC
Purpose: The dramatic changes in morphology, composition, and structure that occur in the
intervertebral disc (IVD) with aging and degeneration are accompanied by specific changes in
material properties. Evaluation of these changes hinges on the ability to objectively and noninvasively assess disc matrix composition and integrity. Different studies on bovine IVDs have
correlated disc matrix composition and integrity to the quantitative magnetic resonance
imaging (qMRI) indicating that MRI signal can be used to predict structural changes in discs
with degeneration. The aim of the present study was to determine correlation between qMRI
parameters and material properties in human discs with different grades of degeneration in
order to evaluate the predictability of mechanical integrity of the disc from the MRI signal.
Method: Fifty human discs (grade 2, 3, and 4 of degeneration) from 10 lumbar spines were
obtained through organ donations via Héma-Québec within 24 hours after death. The qMRI
examinations were carried out in a 1.5T whole-body Siemens' Avanto system. All discs were
graded from T2-weighted images according to the classification system described by Pfirmann.
Numerical analysis of qMRI was performed using a custom code written in MATLAB
(Mathworks, Natick, MA). Confined compression tests were performed on 5 mm diameter
cylindrical plugs of tissue using a custom built axial testing machine. Material parameters
(aggregate modulus HA and permeability k) were obtained from a linear biphasic fit. Dynamic
shear testing was carried out using a rheometer (TA Insturments). Steady state dynamic shear
modulus and phase angle were calculated at each point of the frequency and strain sweeps
and fitted with exponential functions. The correlations between qMRI and mechanical
parameters were investigated using Pearson test performed on GraphPad Prism Software (La
Jolla, CA, USA).
Results: When the tissues were analyzed separately, for the NP tissue significant correlations
were found between T2 and shear modulus |G*| (r = - 0.465, p = 0.022), and between diffusion
ADC and αδ (r = 0.4, p = 0.047). For the AF tissue significant correlation were found between
T1 and phase angle αδ (r = 0.372, p = 0.047) and between T1 and permeability k (r = -0.468, p
=0.043). No correlations were found between MTR and any mechanical parameters for both
AF and NP tissues.
Conclusion: The results of the present study are consistent with our previous studies in
bovine model and indicate sensitivity to distinct changes at varying levels of degeneration. In
the AF, permeability and phase angle were predicted by T1 while in the NP tissue, T2 was a
stronger determinant of the tissue integrity (reflected by shear modulus). These results prove
that it is possible to develop correlations and multiple linear regressions in human IVDs which
are essential for developing quantitative MRI as diagnostic tool for IVD degeneration.
49: Effect of Neonatal mice exposure to Diethystilbesterol on Lumbar and Femoral
Bone and Articular Cartilage in Male and Female Adult Progeny Subjected to Swimming
Exercise
Rahul Gawri, QC; Sora AlRowas, QC; Rami Haddad, QC; Lorraine Chalifour, QC; John
Antoniou, QC; Fackson Mwale, QC
Purpose: Neonatal exposure to Diethylstilbestrol (DES) has been shown to adversely affect a
number of estrogen sensitive tissues, including bone.Effects of in utero DES exposure have
also been shown to affect the third generation. Environmental exposure to estrogens was
shown to be higher than anticipated.The aim of this study is to determine the effect of in utero
exposure to DES on bone and articular cartilage of adult mice.
Method: Pregnant C57/bl mice were injected with either vehicle (peanut oil) or one of three
doses of DES (0.1, 1.0, and 10.0 µg/kg/day) at 11-14 days of gestation.A minimum of 3 dames
was set for each group. Pups were then allowed to grow to adulthood without further
intervention until three months of age.At this point mice were randomized into two groups; one
with a once daily swimming regimen which started as five min. and was escalated to a
maximum of 1 h. The second group were left to their normal activity level and considered
sedentary. All animals were sacrificed at exactly 4 months of age. The knee joint and lumbar
spine was dissected from 3 animals per group. The lumbar and femoral regions of each intact
mouse were scanned for Bone Densitometry. Bone mineral density (BMD), bone mineral
content (BMC), bone area (BA) and trabecular bone area (TBA) were all measured for lumbar
and femoral bones.Histological evaluation was also done on the dissected knee joints.
Results: The lumbar BMCs showed significance at 10.0 µg/kg/day for the female swim group.
The male swim group showed an opposing trend with a dose related decrease in BMC which
became significant at 10.0 µg/kg/day. The femoral BMC interestingly showed opposing trends
for males and females. The swim female femoral BMC showed a significant increase at 10.0
µg/kg/day. The swim male femoral BMC showed a markedly significant decrease at that same
dose. The femoral BMD was slightly more affected than the lumbar BMD. There was a general
trend for decreased femoral BMD which only became significant in the male swim group at
10.0 µg/kg/day. The female sedentary articular cartilage showed decreased staining of the
articular cartilage at all three doses of DES compared to control. In female swim group,
articular cartilage showed decreased staining at 0.1 and 10.0 μg/kg/day of DES. No difference
was noted at 1.0 μg/kg/day of DES. The male sedentary articular cartilage showed increased
staining at 0.1 μg/kg/day of DES, otherwise no difference was noted at the other doses. The
male swim articular cartilage showed decreased staining was at 0.1 μg/kg/day of DES,
otherwise no difference was noted.
Conclusion: Bone and articular cartilage are known to be estrogen-sensitive tissues.Our study
shows that DES in utero exposure can have effect on bone and articular cartilage. The
mechanisms of the effects of DES are however not well understood and further studies are
necessary.This study might shed light on the possible increased risk of disc degeneration in
the sons and daughters of mothers exposed during gestation,as well as their children.
50: Effects Of Photodynamic Therapy In Combination With Radiation Therapy On
Healthy And Metastatically-Involved Vertebrae
Victor Lo, ON; Margarete K Akens, ON; Sara Moore, ON; Albert JM Yee, ON; Brian C Wilson,
ON; Cari M Whyne, ON
Purpose: The cornerstone of spinal metastasis treatment includes radiation therapy (RT),
bisphosphonates (BPs) and surgery. RT is limited by increased risk of fracture post-irradiation
and dose limits, BPs reduce bone resorption but may not destroy tumour tissue and surgery is
associated with a high morbidity. Photodynamic therapy (PDT) has been shown to ablate
tumour cells and enhance bone formation in an athymic rat model of metastatic breast cancer,
demonstrating potential as a treatment for spinal metastasis. When combined with previous BP
treatment, bone formation was further enhanced by PDT. The objective of this study was to
determine the effects of PDT in combination with previous RT on both healthy and
metastatically-involved vertebrae.
Method: Sixty-four athymic rats underwent RT (4Gy) at day 7, with 23 rats inoculated with MT1 human breast cancer cells at day 0 via intracardiac injection. Rats undergoing PDT treatment
received an intravenous injection of BPD-MA photosensitizer on day 14. After a 15-minute
drug-light interval, 75J of light energy was delivered from a 690nm laser adjacent to the L2
vertebra. Rats were sacrificed on day 21 or 56 (healthy only) and structural properties of all L2
vertebrae were quantified via analysis of µCT images. Mechanical properties were evaluated in
half of the specimens by loading the L2 vertebral body to failure in axial compression. The
remaining vertebrae were analyzed for morphology, osteoid formation, osteoclast activity, and
tumour burden using histological methods.
Results: Significant improvements in trabecular structure were found in combined PDT+RT
treated healthy vertebrae compared to RT alone at both short (6% increase in trabecular
thickness) and longer (22% increase in bone volume fraction and 19% decrease in trabecular
separation) time-points. Mechanically, there were no differences in ultimate force and stiffness.
In the metastatic vertebrae, the applied RT dose surprisingly ablated all tumour cells in the
treatment region. Minimal stereological differences and no differences in mechanical properties
were detected between PDT+RT and RT alone treated metastatically-involved vertebrae.
Results were compared to previous data examining untreated and PDT-treated healthy and
metastatic vertebrae. Combined PDT+RT treatment on healthy vertebrae yielded increases in
trabecular structure compared to untreated vertebrae, while RT alone did not yield any
differences. Both PDT+RT and RT-only treatment greatly improved structural and mechanical
properties of metastatically involved vertebrae compared to untreated or PDT-only treatment,
due to the early destruction of tumour in RT-treated groups. Increased amounts of woven bone
and osteoid volume were found in PDT-treated vertebrae.
Conclusion: The ability of PDT to ablate tumour tissue, enhance bone formation, and lack of
detrimental effects on vertebral structure when combined with RT motivates the use of PDT as
a minimally-invasive technique for the treatment of spinal metastasis.
51: Evaluation of Instrumentation Techniques for a Unilateral Facet Fracture Using a
Validated Soft Tissue Injury Model
Stewart D McLachlin, ON; Melissa Nadeau, ON; Stewart I Bailey, ON; Kevin R Gurr, ON;
Cynthia E Dunning, ON; Christopher S Bailey, ON
Purpose: Traumatic flexion-distraction injuries of the cervical spine result in a spectrum of
injury and instability. Anterior, posterior or combined fixation has produced successful
outcomes when generalized to the entire injury spectrum or catastrophic injury models.
However, there is a lack of literature comparing these instrumentation techniques for specific
injury patterns; in this case, a unilateral facet perch (UFP) with an associated facet fracture.
The addition of the facet fracture is especially important in light of recent clinical data
identifying an increased failure rate of the anterior approach in the setting of a facet fracture.
Therefore, the purpose of this study was to use a standardized UFP soft tissue injury model to
evaluate the effects of the addition of a facet fracture, as well as to compare the improved
stability following three surgical fixation techniques.
Method: Five fresh-frozen spinal segments (C4-5) were cleaned of musculature and mounted
in a spinal loading simulator. Stability testing in flexion-extension, lateral bending, and axial
rotation was performed following each stage of the testing protocol. The magnitude of C4-5
range of motion (ROM) was measured using an Optotrak Certus™ tracking system.
Specimens were tested first with the UFP soft tissue injury (both capsules, ¾ of the annulus,
and ½ of the ligamentum flavum), followed by a 50% unilateral facet fracture, and then a
complete unilateral facet fracture. Three proposed instrumentation techniques were then
sequentially tested on each injured specimen. Posterior screw and rod instrumentation was
tested first, followed by anterior plating instrumentation, and finally combined posterior-anterior
instrumentation. ROM of the facet fracture injuries were compared relative to the initial injured
state, while instrumentation techniques were evaluated based on their ability to reduce ROM
relative to the final injured state. Statistical analysis used one-way repeated measures
ANOVAs and post-hoc SNK tests (α=0.05).
Results: Both facet fracture injuries did not cause an increase in ROM beyond the original
UFP soft tissue injury (p>0.05). All three fixation techniques successfully reduced ROM from
the final injured state (p<0.001), but both the posterior and combined approaches allowed less
ROM than the anterior approach in axial rotation and lateral bend (p<0.001).
Conclusion: In this study, the addition of the complete unilateral facet fracture to the soft
tissue injury present in a UFP did not further destabilize the spine as measured by the ranges
of motion in the anatomic planes. However, the instrumentation approaches used to stabilize
the spine showed that anterior instrumentation was inferior to both posterior and combined
approaches in the setting of the unilateral facet fracture. It is suspected that the further soft
tissue destabilization of the spine required for the anterior approach is not reestablished with
instrumentation in the setting of a facet fracture.
52: Structural Evaluation of Whole Vertebrae through Micro Finite Element Modeling and
Histological Damage Assessment
Ryan Herblum, ON; Cari M Whyne, ON
Purpose: Current advancements in computational power and micro-imaging techniques allow
the creation of finite element (FE) models on a micro-structural level that can elucidate the
mechanical integrity of individual trabeculae. However histological validation of such µFE
models has been limited to trabecular cores or in bones with removed endcaps, rather than
whole bone structures. The objective of this study was to evaluate the micro level structural
integrity of healthy vertebrae through µFE modeling validated with histological damage
assessment.
Method: A combination of sequential labeling with loaded-unloaded µCT imaging was
performed to generate and validate µFE models of three wistar rat spinal motion segments.
Calcein green was used to label pre-existing micro-damage. Specimens were µCT imaged
unloaded and under a 100N axial compressive load. Following testing, fucshin staining was
conducted on the whole vertebrae to identify mechanically induced microdamage. µFE models
of the central vertebrae were generated from the unloaded µCT images. Boundary conditions
were applied based on deformable registration with the loaded µCT images. µCT images of the
histology sections were also acquired to locate the corresponding regions within the µFE
model. Damaged (n=20) and undamaged (n=20) regions were identified from the basic fuchsin
histology and compared to corresponding stress and strain values from equivalent locations in
the µFE models. Independent and paired t-tests were performed to compare damaged to
undamaged regions in the whole vertebrae and locally around single trabeculae.
Results: µFE models of the whole vertebrae were successfully generated with accurate
integration of the histologically defined regions. The whole bone sequential labelling process
showed mechanically induced damage within the vertebral trabecular networks. The majority of
damage was observed near the endplates. In comparing histologically damaged to
undamaged regions in the µFE models, significantly higher von-mises stress (max: 263MPa
vs172MPa; avg: 173MPa vs. 115MPa) and principle strains (max: 1.4 % vs. 0.9%; avg: 0.9%
vs. 0.6%) were found in the damaged regions. Similarly, in paired comparisons of adjacent
regions von mises stresses and principle strains were significantly elevated in the damaged
regions.
Conclusion: This study presents a robust method for validating µFE of whole vertebrae. The
adapted staining technique successfully labelled mechanically induced microdamage in the
whole intact vertebrae allowing the evaluation of the effects of ‘physiological loading’ through
the intervertebral discs. The use of image registration to determine boundary conditions
reduced the computational demands of the modeling and registering the multimodal images
enabled the accurate comparison of the 2D histology to the 3D µFE model results.
53: The Effect of Soft Tissue Restraints Following Type II Odontoid Fractures in the
Elderly – A Biomechanical Study
C Maxwell J McCabe, ON; Stewart D McLachlin, ON; Stewart I Bailey, ON; Kevin R Gurr,
ON; Chris S Bailey, ON; Cynthia E Dunning, ON
Purpose: Fractures of the odontoid process are the most common cervical spine injuries in the
elderly, and of these, type II fractures are the most frequent. In this patient population, these
fractures commonly occur with low-energy injury mechanisms, including falls from a standing
height. With this mechanism, some restraints to displacement, such as those provided by the
ligamentous structures, remain in the setting of a type II odontoid fracture in an elderly patient.
The stabilizing role of these soft tissue restraints in this context has not been explored in the
literature. The purpose of this study was to determine the restraint to pathological motion
provided by the passive soft tissues stabilizers surrounding the C1-C2 joint in the setting of a
simulated type II odontoid fracture in cadavers older than 75 years of age.
Method: Ten cadaveric CO-C2 spinal segments were studied. Specimens were tested under
simulated axial rotation with an applied moment of ±1 Nm and with the direct application of 10
N anteriorly-directed force to the body of C2 to induce sagittal translation. Optical motion data
was initially collected for the intact state, and after a simulated dens fracture. The specimens
were then divided into two groups, where one group underwent unilateral then bilateral C1-C2
facet capsular injuries followed by anterior longitudinal ligament injuries. The second group
underwent the anterior longitudinal ligament injure prior to the same capsular injuries. Changes
in axial range of motion (ROM) and C1-C2 translation were recorded and were analyzed using
two-way repeated measures ANOVAs and post-hoc Student-Newman-Keuls tests (α=0.05).
Results: In axial rotation, there was an increase in ROM by approximately 13% with the
fracture of the dens compared to the intact state (p<0.05). An increase was also present for
each subsequent soft-tissue injury state compared to the previous (p<0.05); however, there
was no difference found between the two soft tissue sectioning protocols. For sagittal
translation testing, it was found that the odontoid fracture alone showed an increase of 3 mm
of C1-C2 translation compared to intact (p<0.05). Further soft tissue injuries did not show an
increase until the complete injury state.
Conclusion: The provocative sagittal translation loading demonstrated the previously
recognized role of the dens as a primary stabilizer. There was essentially no translation in the
intact state and the dens fracture led to an increase in translation of approximately 3 mm.
However, no further increase was seen with sequential ligament sectioning until all tested
ligaments were sectioned. This illustrates that the ligaments do not provide a cumulative
influence, but rather an “all or nothing” effect. This helps to support the hypothesis that the
surrounding soft tissues will provide an important stabilizing influence in an odontoid fracture
produced by a low energy mechanism in an elderly patient.
54: The Therapeutic Potential of Link-N in the Treatment of Human Intervertebral Disc
Degeneration
Rahul Gawri, QC; Fackson Mwale, QC; Jean Ouellet, QC; Thomas Steffen, QC; Peter
Roughley, QC; Lisbet Haglund, QC; John Antoniou, QC
Purpose: Intervertebral disc degeneration is the single most common implicated cause of back
pain. Presently there is no medical treatment and surgery is the only offered option.Link-N
peptide has been speculated to play a role in matrix homeostasis by promoting new matrix
synthesis.We evaluated its regenerative potential in intervertebral discs by means of a whole
organ culture model developed by us.
Method: Lumbar IVDs, from 7 individuals were obtained through organ donations via
Transplant Quebec within 6 hours after death. Cellular studies were performed on cells
isolated from nucleus pulposus (NP) and inner annulus fibrosus (iAF) regions of the discs.
Cells were beaded in 1.2% alginate and exposed in culture to Link-N for 48 hours in
concentrations ranging from (10-10000) ng/ml for dose response.The discs were prepared for
organ culture and cultured with no external load applied. Link-N was conjugated with 5-TAMRA
dye and distribution of Link-N in the medium and within the disc after injection was studied to
see whether Link-N is retained in the disc due to interaction with the matrix or diffuses out.
Discs from adjacent levels were injected in their NP region with 50µCi of 35SO4 along with
0.1mg or 1mg of Link-N in 100µl of medium per disc and harvested after 48 hours.Sustained
regenerative effect of Link-N was evaluated by injecting the disc with Link-N and injecting
35SO4 one week later.Response to Link-N was evaluated by monitoring 35SO4 incorporation.
Results: Human lumbar disc cells from NP and iAF regions beaded in alginate were exposed
to Link-N peptide for 48 hours and proteoglycan synthesis was observed to increase in a dose
dependent manner with the maximal response at 1000ng/ml of Link-N. To determine if Link-N
freely diffuses throughout the disc and equilibrates with surrounding medium, 1mg Link-N
peptide conjugated with 5-TAMRA dye was injected. TAMRA-Link-N was detectable in the
medium at 24 hours and reached equilibrium after 48 hours. The fluorescent peptide was
found to localize in NP and NP/iAF junction but its further diffusion in the disc was restricted by
collagen fibers.Loss of Link-N appears to occur by diffusion through the endplates. Discs
injected with Link-N showed increased proteoglycan synthesis in the NP and iAF compared to
adjacent level control discs. To evaluate the duration of the effect, discs were injected with
35SO4 one week after the injection of Link-N and continued to show an increase in
proteoglycan synthesis thus suggesting a sustained effect of Link-N in increasing proteoglycan
synthesis.
Conclusion: In this work we show that Link-N can promote proteoglycan synthesis 3D cultures
of human disc cells. Link-N has the potential to be a candidate for biologically induced disc
repair as increased proteoglycan synthesis was observed in intact human discs.In the future,
Link-N may provide an alternative to surgery for early stage disc degeneration. Link-N has a
significant cost advantage over other bioactive proteins such as BMP7, TGF-B and GDF5.
Link-N is over 100 times less expensive than recombinant growth factors that have a similar
repair response.
55: A Prospective Randomized Multicentre Evaluation of a “New” MIS Approach to THA:
Stem Subsidence an Issue?
Nelson V Greidanus, BC; Samir Chihab, BC; Donald S Garbuz, BC; Bas A Masri, BC;
Michael Tanzer, QC; Allan E Gross, ON; Clive P Duncan, BC
Purpose: To examine the potential superiority of a “new” intermuscular surgical approach to
limited incision total hip replacement.
Method: After a learning curve which included a hands-on course and a combined number of
95 cases (minimum 10 per surgeon), five subspecialized hip surgeons, at three academic
centres, participated in the study of a “new” anterolateral MIS approach to THR. It was a
multicentre, prospective, randomized trial, comparing it to the “standard” limited incision
approaches already in use (direct lateral or posterolateral). HRQoL outcomes were assessed
at baseline and intervals out to 24 months. Detailed, blinded, radiographic measurements were
performed on 134 cases (representing all three sites) including cup alignment in two planes,
stem alignment, subsidence, loosening and fractures. Parametric and nonparametric analyses
were performed.
Results: A total of 156 patients were recruited and the same implant system used in every
case. There was no difference between groups at baseline (pre-op age, gender, BMI,
comorbidity, WOMAC). Similarly, interval HRQoL outcomes out to 24 months were not different
(p>.05). Cup and stem alignment were satisfactory with no difference between the groups at all
sites(p>.05). However stem subsidence was 4.6mm for G3 approach and 4.1mm in the
alternate group with significant differences observed on inter-site analyses for subsidence
(p=.004). An increased rate of trochanteric fractures was observed and two patients in the
“new group” have already required revision.
Conclusion: This study failed to demonstrate superiority with the “new” anterolateral (socalled G3) approach. Detailed radiographic analyses demonstrates inter-site differences in
painful stem subsidence and fracture. Likely this is related to the greater technical challenge of
exposure with this approach in some patients, leading to the risk of undersizing the stem in
those cases. The authors have returned to the standard surgical approaches in use before the
trial.
56: A Single-Centre Preliminary Experience of the Anterior Approach for Total Hip
Arthroplasty
Paul E Beaulé, ON; Paul R Kim, ON; Kyle A Kemp, ON
Purpose: The anterior approach is the only purely internervous and intermuscular approach to
the hip. Despite these advantages, its use in Canada remains limited. The purpose of this
study is to present the short-term results and complications with this approach.
Method: Over a 40-month period, 200 anterior approach THAs were performed at our centre
by two surgeons in 184 patients: 121 males & 63 females; mean age 63.61 yrs (33 to 92);
mean BMI 28.33 (18.6-44.6). Eight of 16 patients underwent simultaneous bilateral THA.
Patients completed the Western Ontario and McMaster Universities Osteoarthritis Index
(WOMAC) prior to surgery and at latest follow-up.
Results: At follow-up of 24-60 months, WOMAC scores improved significantly (p<0.001 in all
cases). Two patients deceased unrelated to surgery. Four cases of calcar fracture were
managed intra-operatively using cable fixation. Two femoral canal perforations were
recognized intra-operatively. Seven complications occurred within first 8 post-operative weeks:
5 infections (two of which required an irrigation & debridement); 1 DVT and 1 iliac wing
fracture. In total, eight re-operations were required at a mean time of 23 months (11-40mos): 5
in large Head MOM, 1 Accolade Stem loosening and 2 deep infections requiring two-stage reimplantation.
Conclusion: Based on our early results, the anterior approach is a reasonable alternative to
the traditional anterolateral or posterior surgical approaches for THA. Further long-term studies
and comparisons to other approaches will determine if the anterior approach will become the
preferred approach for total hip arthroplasty.
57: Comparison of Outcomes and Survivorship Between Patients of Different Age
Groups Following Total Hip Arthroplasty
Murray C Blythe, ON; Chris Robert, ON; James L Howard, ON; Douglas Naudie, ON; James
P McAuley, ON; Richard McCalden, ON; Robert B Bourne, ON; Lyndsay Somerville, ON;
Steven JM MacDonald, ON
Purpose: Total hip arthroplasty offers both patients and surgeons excellent and predictable
clinical results in the treatment of arthritis of the hip. It is being performed with increasing
frequency in younger patient populations. The purpose of this study was to evaluate and
compare the survivorship (5 and 10 year) and clinical outcomes of patients of different age
groups that underwent THA at our institution.
Method: A retrospective review based on a prospective database was performed on 5,047
consecutive patients that underwent primary THA between January 1996 to December 2009.
Patients were then divided into 3 groups based on their age: <55, 55-70 and >70 years.
Clinical outcomes were assessed using the WOMAC, SF-12 and Harris Hip Score (HHS). The
outcome score change was determined by subtracting the preoperative score from the most
recent available postoperative score. The outcome score change was then compared between
the 3 age groups. Kaplan-Meier analysis was performed on each group of patients to calculate
survivorship at 5 and 10yrs with revision for any reason being the endpoint.
Results: Comparing the <55, 55-70 and >70 age groups respectively, there was a statistically
significantly difference in the WOMAC total change score (41 vs 38 vs 34, p<0.0001). This
pattern of change was also found when the WOMAC was broken down into its subscales
including pain, stiffness and function. There was also a statistically significant difference in the
change in HHS favoring the younger populations (<55rys: 45.0 vs 55-70yrs: 43.6 vs >70yrs:
40.7). The Kaplan-Meier survivorship for the <55, 55-70, and >70 years age groups at 5 years
was 96.6%, 96.0% and 96.2% and at 10 years was 93.0%, 94.2% and 95.9% respectively.
Revision secondary to infection was a major cause for failure in the older age groups while
polyethylene wear was the most common means of failure in the <55 age group.
Conclusion: This study has shown that younger patients experience better clinical outcomes
following THA according to the HHS, WOMAC and SF-12, and similar survivorships, when
compared to older patient populations. THA is an excellent treatment for arthritis of the hip,
even in younger patients.
58:
Compliance with Thromboprophylaxis using an Oral Factor Xa Inhibitor
(Rivaroxaban) after Total Hip and Knee Arthroplasty. Is Oral therapy better? An
Examination of the Non-Adherence rate of Rivaroxaban
Sebastian R Rodriguez-Elizalde, ON; John J Murnaghan, ON; Helen Razmjou, ON; Debbie
Murnaghan, ON; Jeffrey Gollish, ON; Benedict A Rogers, ON; Andrew Carrothers, ON
Purpose: Post-operative thrombo-prophylaxis is believed to reduce the perioperative risk for
patients following total hip and knee arthroplasty. The non-adherence rate in the literature for
patients completing their prescribed course of traditional thrombo-prophylaxis varies from 540%. Newer oral thrombo-prophylatic agents are now available (factor Xa inhibitors), however
their patient compliance rate is unknown. This study compares the compliance rate of a
prescribed oral factor Xa inhibitor, Rivaroxaban®, for the thrombo-prophylaxis of postoperative hip and knee arthroplasty patients and compares it to the established literature
compliance rates of other modalities. The non-adherent patients were then subgroup analysed
to examine for non-compliant patient risk factors.
Method: Since January 2010, an on going prospective database for all total joint replacement
surgeries has followed patients treated with thrombo-prophylaxis post-operatively. As a
standard of care, a self-administered questionnaire is recorded at the six-week mark. This
includes information about the medication used for thrombo-prophylaxis, the prescription
administration, compliance and complications from therapy. The compliance of their prescribed
fifteen-day therapy was then calculated and compared to the published literature compliance
rates of other thrombo-prophylaxis agents. A sub-group analysis was then undertaken of the
non-adherence (NA) group.
Results: A total of 1789 patients (1045 total knees and 744 total hips) received a prescription
for Rivaroxaban post-operatively. Of these, 53 (3.0%) did not complete their six-week follow up
questionnaire. Another 52 (2.9%) stated they did not complete the entire course of prescribed
therapy. The overall compliance rate of those given a prescription is 97.1%. If we assume all
those lost to follow-up did not complete their prescribed course, the compliance drops to
94.1%, leaving a non-adherence (NA) rate of 5.9% for Rivaroxaban. The group of stated nonadherent patients were more likely to be female (71.2% vs 60.1%, p=0.03), and were trending
to have a higher BMI (30.6 vs 28.9, p=0.08). Age was not a factor for either group. Four
patients who were NA encountered bleeding complications, compared to 18 in the compliant
group (7.5% vs 1.1% p=0.01).
Conclusion: This study demonstrates that patients are more likely to complete a thromboprophylaxis regime on an oral Factor Xa inhibitor than other therapies. The stated NA rate of
prescribed Rivaroxaban is 2.9%. Assuming all those lost to follow-up were non-adherent, the
calculated overall NA rate would be 5.9%. This compares favourably to the non-adherence
rates of injectable low molecular weight, which has multiple published series demonstrating NA
of 5-40%, and most recently, a large multi-center series of 1315 patients showing a NA of
20.8%. This study demonstrates that the prescription of rivaroxaban affords a superior patient
compliance compared with subcutaneous LMWH.
59: Evaluation of the use of Spinal Epimorph in Total Hip Arthroplasty: A Prospective
Double-Blinded Randomized Control Trial
Rajrishi Sharma, ON; Aaron Bigham, ON; Sugantha Ganapathy, ON; James P McAuley, ON;
Richard McCalden, ON; Douglas Naudie, ON; Steven JM MacDonald, ON; Robert B Bourne,
ON; James L Howard, ON
Purpose: The primary preoperative concern for patients undergoing total hip or total knee
arthroplasty is the anticipation of pain postoperatively. With increasing demand of total joint
arthroplasty, focus in obtaining the most comfortable anesthetic with minimal complications is
paramount. Spinal anesthesia with adjuvant intrathecal opiates have been used since the early
1980’s with no focus on whether there is a clinical benefit within the arthroplasty population.
The purpose of our study was to determine in patients undergoing total hip arthroplasty
whether spinal with epimorph versus spinal without epimorph resulted in better pain control
and fewer complications. We hypothesized that there would be no difference in pain control
and higher complication rate in patients undergoing total hip arthroplasty with intrathecal spinal
epimorph.
Method: We performed a prospective double-blinded randomized clinical trial with 60 patients
(31 with spinal epimorph and 29 without spinal epimorph). Pain was assessed using the visual
analogue pain score and narcotic usage was recorded at various time intervals. Any
complications were recorded.
Results: Our study found a statistically significant improvement in pain six (p=0.001) and 12
hours (p=0.003) post surgery and significant decrease in narcotic usage between 6-12 hours
post operative (p=0.009). Beyond 18 hours there was no statistical difference between the two
groups. There was however, a statistically significant increase in complications with spinal
epimorph including need for Foley catheter (p=0.024), nausea (p=0.020), vomiting (p=0.006)
and pruritis (p=0.015).
Conclusion: This study confirms improved clinical pain scores with spinal epimorph only
within the first 18 post-operative hours. However, increased complications have been found.
Therefore, care must be taken if intrathecal epimorph is used. To decrease these
complications, the use of known pre-operative analgesic modalities and intra-operative local
anaesthetic mixtures may eliminate the need for intrathecal epimorph.
60: Inpatient Mortality after Primary Total Hip Arthroplasty: Analysis from the National
Inpatient Sample Database
Kenneth David Illingworth, IL; Youssef el Bitar, IL; Devraj Banerjee, IL; Steven L Scaife, IL;
Wendy M Novicoff, IL; Khaled J Saleh, IL
Purpose: As the population ages, the number of patients requiring total hip arthroplasty for
end stage osteoarthritis will continue to grow. Although inpatient mortality rates following total
hip arthroplasty are low, understanding factors that influence inpatient mortality rates are
critical in order to maximize patient safety. The purpose of this study was to assess factors that
influence inpatient mortality rates after primary total hip arthroplasty in a large national
database. Our hypothesis is that increased mortality will be associated with an increased age
and the presence of inpatient complications.
Method: Weighted discharge data from the 2007-2008 HCUP Nationwide Inpatient Sample
database were used in this study. Patients were identified based on whether they were
admitted for a primary total hip arthroplasty using the International Classification of Disease
and Related Health Problems (ICD-9-cm) code and grouped based on their inpatient mortality
status. Mortality rates were explored using patient demographics, hospital demographics,
inpatient complications, co-morbidities, elective vs. non-elective surgery and weekend
admissions. Univariate analyses and an adjusted logistic regression analysis revealed a large
number of relevant variables. A principal components analysis was used as a strategy to
reduce the number of variables in the final logistic regression model.
Results: In 2007-2008 there were 530,079 primary total hip arthroplasty discharges with an
inpatient mortality rate of 0.20%. Frequency of mortality was significantly higher for increased
inpatient complication rates (Pulmonary > Cardiovascular > Mechanical wound > Systemic >
Infection > Gastrointestinal > Urinary), weekend/elective surgery admission, increasing age
and having Medicare payer provider. Using a principal components analysis, 5 factors were
identified that were significantly related to mortality. The five factors are listed with odds ratios
and 95% confidence intervals and included a Demographic Factor (Age/Payer Status
((Medicare/Medicaid/Private/Other))(0.793, 0.742-0.847), a Location Factor (age/rural or urban
location/median household income/location of hospital)(1.113, 1.058-1.171), an Elective Factor
(elective or non-elective surgery/weekend admission)(5.42, 4.736-6.201), a Co-Morbidity
Factor (Charlson Score/diabetes/obesity/sleep apnea)(0.702, 0.654-0.755), and an Inpatient
Complication
Factor
(cardiovascular/pulmonary/
mechanical/wound/infection/systemic/
gastrointestinal /urinary)(0.168, 0.156-0.181). The odds ratios for all 5 factors were significant
(p < 0.05).
Conclusion: Mortality rates following total hip arthroplasty were significantly affected by
multiple factors and these factors should be taken into account for any patient undergoing
primary total hip arthroplasty. Most significantly, inpatient complications should be minimized at
all costs as these were associated with the highest increased frequency of mortality.
61: Outcomes and Complications of Total Hip Arthroplasty in the Super-Obese: A
Retrospective Analysis
Raghav Rajgopal, ON; Robin Martin, ON; James L Howard, ON; Douglas Naudie, ON; James
P McAuley, ON; Richard McCalden, ON; Steven JM MacDonald, ON; Robert B Bourne, ON
Purpose: Obesity is a global epidemic and leads to a multitude of adverse health outcomes
including osteoarthritis. Obese patients tend to require joint arthroplasty at earlier ages
compared to normal weight patients. Many studies looking at perioperative arthroplasty
complications and outcomes in obese patients demonstrate no significant differences
compared to normal weight patients. However, there is limited data examining outcomes
specifically in super-obese (BMI > 50) patients, which is an increasingly prevalent population.
The purpose of this study was to examine complication rates in super-obese patients
undergoing total hip arthroplasty.
Method: Forty super-obese patients who underwent total hip arthroplasty were identified in our
institution from 1998-2009. There were 33 women and 7 men with a mean age of 53. This
group was matched to patients of normal weight (BMI 20.1-24.9) and class I obesity (BMI 30.134.9). Patients were matched for age, gender, length of follow-up, and pre-operative diagnosis.
Groups were then examined for differences with respect to implant, transfusion rate, surgical
time, length of hospital stay, satisfaction (WOMAC, HHS, SF-12), complications, readmission
rate, and re-operation rate. Differences were determined using ANOVA, Tukey test, and Fisher
exact test (p < 0.05).
Results: A retrospective analysis was performed examining complications and patient
satisfaction. We found that super-obese patients demonstrate an increased length of stay in
hospital (p < 0.05), nine-fold increase in major complication rate (p < 0.001), six-fold increase
in re-admission rate (p < 0.05), and six-fold increase in re-operation rate (p < 0.05) compared
to normal weight and class I obesity groups. Although super-obese patients demonstrated
reduced pre- and post-operative satisfaction scores, there was no significant difference in
improvement, or change score, with respect to SF-12, HHS, or WOMAC.
Conclusion: Super-obese patients obtain similar satisfaction outcomes as class I obesity and
normal weight patients with respect to change scores. However, they experience a significant
increase in length of hospital stay, major complication rate, re-admission rate and re-operation
rate.
62: PATH? Total Hip Arthroplasty – Improved Early Mobility and its Economic Impact in
a Canadian Centre
Cai Wadden, ON; Alan Forster, ON; Jodi Pachal, ON; Wade T Gofton, ON
Purpose: The purpose of this economic analysis was to compare the direct hospital cost of a
traditional Total Hip Arthroplasty (THA) to a THA performed using a Percutaneously Assisted
Total Hip (PATH).
Method: Fifty
with fifty matched conventional THA patients performed by a single surgeon at a single
hospital. Patients undergoing bilateral procedures or having severe contralateral arthritis
affecting mobilization were excluded.
Results: The two patient cohorts were found to be similar with respect to average age, gender,
ASA classification and body mass-index. Pre-hospital costs were found to be equivalent. Early
operative times were longer f
min – 5 min for intra-operative ximplant prices were higher due to modularity options, the use of a disposable reaming cannula
and fixed hospital contracts. However significant savings are realized based on reduced
transfusion rates (4% versus 26%), acute care length of stay, 2.96 versus 4.26 days and both
the necessity for rehabilitation (12% versus 36%) and duration when required (9.5 versus 12.8
days). There was no significant difference in complications or readmission rates between
groups. No obvious difference in Home care utilization was identified.
Conclusion: Despite a slight increase in implant costs and disposables the PA
preserving technique allowed for earlier mobilization and reduced length of acute care stay.
The percentage of patients requiring a rehabilitation stay was also significantly reduced. It is
possible to extrapolate that with a shorter LOS, various daily costs for medications, other
administered products and service related costs are not incurred that otherwise would be with
patient length of stay, both in the acute care and rehab setting, and hospital costs.
63: Simultaneous versus Staged Bilateral Total Knee Arthroplasty: A Meta-analysis
Evaluating Mortality, Peri-operative Complications and Revision Surgery Rates
Nasir Hussain, ON; Ammar Bookwala, ON; Teresa Chien, ON; Nicole Simunovic, ON; Vijay
Shetty, IN; Mohit Bhandari, ON
Purpose: An important debate in many orthopaedic practices is the choice of performing
simultaneous or staged bilateral total knee arthroplasty. The objective of this meta-analysis is
to determine the effect of simultaneous bilateral and staged bilateral total knee arthroplasty on
peri-operative complication rates, revision rates and mortality.
Method: A search strategy was developed to identify all relevant citations from the MEDLINE,
EMBASE and COCHRANE databases and the unpublished literature. Assessment of the
studies for methodological quality and content was conducted independently by two reviewers
who extracted all relevant information from the included studies. The data was categorized into
subgroups and pooled using the DerSimonian and Laird’s random effects model.
Results: A total of 18 articles were identified from 873 potentially relevant titles and selected
for inclusion in the primary meta-analyses. The incidence of mortality was significantly higher in
the simultaneous group at 30 days (Risk Ratio (RR) 3.31, 95% Confidence Interval (CI) 1.766.23, p = 0.001, I2 = 33%, sample size (n) = 67,784 patients), 3 months (RR 2.45, 95% CI 2.15
– 2.79, p < 0.001, I2 = 0%, n = 66,474 patients), and 1 year (RR 1.85, 95% CI 1.66 – 2.06,
p<0.001, I2 = 0%, n = 65,322 patients) post-surgery. The rate of revision surgery was
significantly lower in the simultaneous group (RR 0.36, 95% CI 0.16 – 0.81, p<0.05, n = 752
patients) two years post-surgery. There was no increased risk of deep vein thrombosis, cardiac
complication, pulmonary embolism, or infection rates in either comparison group.
Conclusion: The results of the analysis suggest that simultaneous bilateral total knee
arthroplasty has a significantly higher rate of mortality at 30 days, 3 months. and 1 year postsurgery, and a significantly lower rate of revision surgery two years post surgery. These results
should be interpreted with caution due to the inclusion of nonrandomized studies in the primary
meta-analyses.
64: The Ottawa Experience using a Modular Femoral Neck System for Primary Total Hip
Arthroplasty
Emmanuel M Illical, ON; Paul E Beaulé, ON; Robert Feibel, ON; Peter Thurston, ON; Paul
Kim, ON; Wade T Gofton, ON
Purpose: Modular neck systems for total hip arthoplasty offer the ability to alter femoral
version, offset, and leg length independently from the femoral stem that has been inserted.
However, concerns have been raised about neck fracture as well as corrosion at the modular
head-neck interface. The purpose of this study was to describe the experience of using a
modular neck system at our institution and to report any potential complications.
Method: Between January 2006 and June 2011, 580 primary total hip arthroplasties were
performed at our center using either a flat tapered wedge geometry femoral stem or
rectangular tapered stem with a titanium modular neck option (Profemur TL and Z) by five
different surgeons with 3 surgical approaches: posterior, anterior, or lateral. Implant details
were recorded in a database at the time of surgery and the patients are being prospectively
followed for any complications associated with the modular femoral neck.
Results: The patient demographics were as follows: mean age 61.5 +/- 12 years; mean height
168 +/- 12 cm; mean weight 81 +/- 19 kg; 318 females (55%) and 262 males (45%). A neutral
neck was used in only 18.6% of cases (106/580). The most common neck used was the
varus/valgus accounting for 56.9% of cases (330/580). The anteverted/retroverted options
accounted for 12.9% of cases (77/580). The anteverted/retroverted and varus/valgus option
accounting for 11.2% of cases (65/580). Ninety two percent (533/580) of necks implanted were
short with 57% (302/533) being female. Only 8% (47/580) of necks were long with 66% (31/47)
being males. There were no complications associated with the modular femoral neck at the
latest follow up for all patients.
Conclusion: A significant number of patients benefitted from the modular necks in optimizing
their biomechanical reconstruction. Unlike previous reports, at mid-term follow-up there were
no complications associated with the modular femoral neck in our series with only 8% of
patients requiring the long neck options. Further long term follow-up is required to determine if
other failure modes will occur.
65: A Pilot Randomised Controlled Trial Evaluating the Effectiveness of Virtual Reality
Arthroscopic Knee Training in an Orthopaedic Residency Program
Jesse Alan Shantz, US; Jeff Leiter, MB; Jason A Old, MB; Gregory Stranges, MB; Jamie H
Dubberley, MB; Peter B MacDonald, MB
Purpose: The purpose of this study was to validate the use of a virtual reality haptic knee
simulator with embedded skills mentor in arthroscopic education through a pilot randomized
controlled trial. A previously validated global arthroscopic skills assessment was used to
determine the effects of an arthroscopic virtual reality surgical simulator on the development of
arthroscopic skills assessed during a diagnostic arthroscopy performed on a cadaveric knee.
Method: A total of 14 residents were assessed on pre-study ability to perform a diagnostic
knee arthroscopy using a procedure-specific checklist and global assessment of skills after
consenting to this IRB-approved study. Participants were then stratified by arthroscopic
experience and randomized to receive a VR simulator training program or standard training.
The simulator-trained group completed a computer-mentored course (ToLTech, Aurora, CO)
including periodic skills assessments within six week training period. At the conclusion of the
VR simulator training period all participants were again assessed on their ability to perform a
diagnostic knee arthroscopy and retention of skills was assessed after a six week washout
period. Results were presented as mean difference skills with differences between groups
assessed using the Student’s t-statistic and presented as 95% confidence intervals.
Results: Pre-randomization skills in the groups were not significantly different. The control
group had a larger number of junior residents. There was a wide variation in adherence to the
mentored simulator program. Mean difference of global skills was not found to be different
between VR simulator-trained and control groups (p=0.52). The retention of skills was also not
different between the two groups (p=0.15). Of note, both groups showed significant
improvements in skills during the study and retained those improvements after six weeks
(mean improvement 16.5%, 95% C.I. 6.4%-26.5%). Based on this pilot a group size of 51
participants would be necessary to show a statistically significant difference in skills
improvement after this educational intervention.
Conclusion: The results of this study suggest there is no difference in arthroscopic skills
improvement after six weeks of simulator training as measured by a global objective
arthroscopic skills assessment. This finding was tempered by the variable adherence to
simulator training in the treatment group. Of note, the average skill of participants showed a
statistically significant improvement equal to the difference between junior-level skills to seniorlevel skills. Future studies need to look at the ability of this training program to improve
orientation to arthroscopy-based rotations.
66: Casting Simulation in Orthopaedics: Improving a Lost Art
M Lucas Murnaghan, ON; Joel Moktar, ON; Charles A Popkin, ON; Andrew Howard, ON
Purpose: With decreased work hours and an increased role of operative fixation for distal
radius fractures, orthopedic trainees are losing experience and expertise in proper cast
application. Technical deficiencies in casting skill have been demonstrated to result in higher
rates of re-displacement and cast specific complications. Although this loss of ability has been
described and lamented, no formal education modules exist to instruct or evaluate casting
technique without the use of a patient. Existing educational methods are insufficient as they
cannot objectively measure cast quality and offer limited practice opportunities.
Method: A novel educational module that simulates the required reduction and appropriate
cast application for a distal radius fracture in a synthetic forearm model was developed. An
Objective Structured Assessment of Technical Skill (OSATS) was created using Delphi
methodology involving nine content experts (five Orthopedic Surgeons and four Orthopedic
Technologists). Nine de-indentified videos of cast application were recorded and utilized to test
the newly developed OSATS and Modified Global Rating Scale (MGRS) for reliability and
validity. The casting simulator participants were grouped by training level.
Results: The OSATS scores improved with increasing level of training: 9.3 for Medical
students (MS), 17.5 for Residents (R) and 18.9 for Fellows/Techs (F/T) (p <0.05, F score 6.12)
tested with ANOVA and confirmed with Tukey test. MGRS Performance similarly improved with
level of training: 1.44 MS, 3.13 R and 3.54 F/T (p <0.05, F score 6.37). Reliability was rated as
high by Intraclass correlation. Inter-rater reliability for the OSATS, GRS Performance and GRS
Final Product was 0.85, 0.81 and 0.78 respectively and intra-rater reliability was 0.88, 0.85 and
0.81 respectively.
Conclusion: This casting simulation model and evaluation instrument is a valid assessment of
objective skill in applying a short arm cast for a distal radius fracture. Scores increased with
level of orthopedic training and casting experience. This simulator will allow for improved
teaching and learning of casting techniques to medical students and residents across a variety
of disciplines. The improved application of short-arm casts for distal radius fractures will allow
for better patient care and subsequent clinical outcome.
67: Developing a Model for Simulator Training and Evaluation of Arthroscopic Skills
Ivan H Wong, ON; David Newman, ON; Matthew Denkers, ON; Forough Farrokhyar, ON
Purpose: The purpose of this study was to develop a simulator-teaching model for knot tying
and objectively evaluate the acquired skills of surgical trainees.
Method: Surgical trainees were enrolled in an observational study (Phase I, n=32). Subjects
viewed an instructional video and pretested on a novel knot-tying simulator by attempting to tie
three arthroscopic SMC knots in 10 minutes. Each knot was objectively scored based on a
previously published formula (Derossis et al 1998). Subjects were assessed twice with
intermittent practice and feedback during a 90-minute lab session. This experiment was
repeated 6 months later to determine retention of acquired skills (Phase II, n=25). The mean
proficiency score with standard deviation and mean difference with 95% confidence intervals
(CI) are reported; a generalized linear regression model was used for analysis.
Results: Expert derived proficiency score (489) was used as the standard for competency.
Phase I, the mean proficiency score of 32 trainees was 67 (119), 239 (201) and 334 (140) at
baseline, assessment 1 and assessment 2, respectively. The mean proficiency score of 334
(140) was significantly lower than expert proficiency score (-155 (95% CI: -205.5, -104.5),
p<.001). After a 6-month interval (Phase II), these skills were not retained. The mean
proficiency score difference from Phase I assessment 2 to Phase II baseline was -222.8 (95%
CI: -302.7, -142.9, p<.001). At Phase II, the mean proficiency score of 25 trainees increased
from 110 (138) at baseline to 362(118) at assessment 1 and 408 (99) at assessment 2. The
mean proficiency score was significantly lower than expert proficiency score (-81 (95% CI: 122, -41), p<.001). Adjusting for year of residency, gender, age, previous experience and
phase I and II training model, the simulator training model (p<.001) and year of residency
(p=.004) were the best predictors of proficiency scores improvement.
Conclusion: Simulator training models have a place in orthopaedic education for teaching
basic arthroscopic skills. However, frequent practice is necessary to ensure retention of
acquired skills.
68: Implementation of a Novel Night Float Call System: Resident Satisfaction and
Quality of Life
Stephen M Mann, ON; Graham Fedorak, ON; Daniel P Borschneck, ON; Mark M Harrison,
ON
Purpose: To evaluate the satisfaction of orthopaedic residents with a novel call system after
its implementation at an Ontario tertiary care centre, and to measure quality of life following
this implementation.
Method: Due to relatively small program size (16 residents) and clinically active attending
surgeons, compliance with PAIRO duty-hour guidelines has historically been problematic at
our institution. In an effort to facilitate residents’ ability to go home post-call without significant
disruption of ongoing clinical activities, a novel call system was adopted. A “night float” resident
was designated, and was assigned only to on-call duties for a full four-week (one block)
rotation. During this time, the night float resident was not attached to any of the regular
orthopaedic services and had no additional clinical responsibilities. Duty hours were 1700h to
0600h each day from Sunday to Friday, with cessation of clinical duties on Friday morning until
Sunday evening. Friday and Saturday call were performed by other residents in the regular 24hour fashion, as the subsequent days, being weekends, had no clinical duties and residents
could easily be excused post-call. In addition, other residents were on call each evening of the
week until 2300h, at which point they were excused. This allowed for additional manpower
during typically busy evening hours, leaving the night float resident on call alone from 2300h to
0600h, and permitting the residents who were on call only until 2300 to be present for the next
clinical day. After implementation of this call system, questionnaires were administered to onservice residents. These included the SF36 and those used by Zahrai et al to address topics
such as education, stress, work-related problems, and miscellaneous concerns. Qualitative
feedback was also solicited from nursing and ER staff.
Results: Quality of life for residents on the night float block did not demonstrate significant
improvement over baseline values established by Zahrai et al. However, for those residents
who were on service while another resident was performing night float duties, quality of life was
substantially improved. Overall satisfaction with the system was high among residents, nurses,
and the emergency department. Improved resident mood and greater cheerfulness were
subjectively commented upon. In addition, attending staff found that this system facilitated
effective feedback. At our institution, attending staff perform call one week at a time, and they
were able to continuously interact with one resident over that time, rather than with a different
resident each night.
Conclusion: This call system results in improved resident quality of life and widespread
overall satisfaction while allowing adherence to PAIRO duty-hour restrictions without undue
disruption of clinical activities, and may be considered as a viable alternative to traditional call
formats. Follow up data as more residents experience the night float block will be valuable.
69: Occupational Risk in Orthopaedic Surgery: Is the Use of Fluroscopy Hazardous to
Your Vision?
Marcia L Clark, AB; Roxanne Chow, AB; Chris Rudinsky, AB; Lauren Beaupre, AB; David
Otto, AB
Purpose: Ionizing radiation, such as that used in fluoroscopy, conventional radiography and
computed tomography, in high doses, can lead to the development of cataracts. Although the
documented exposure levels to the eyes are low in Orthopaedic Surgery, given the potential
risk of even low dose exposures, the ultimate risk to the orthopaedic surgeon is unknown but is
potentially valid and serious. The purpose of this study was to determine amongst orthopaedic
surgeons and residents in Canada: 1) perceived level of personal risk for cataract formation
from ionizing radiation exposure: 2) awareness level regarding the risk of cataract formation
due to ionizing radiation exposure: 3) awareness regarding the existence of ICRP and NCRP
dose limits for the amount of radiation exposure to the eyes in an occupational setting: 4)
current radio-protective practices.
Method: A descriptive e-mail survey was administered to members of the Canadian
Orthopaedic Association in 2010. Survey design was performed through review of the
literature, application of rigorous design principles, expert content review and initial piloting in a
local environment.
Results: A total of 264 responses were received (1132 distributed questionnaires) for a
response rate of 23%. Almost half of the respondents believed that they were at either
moderate (n=107;41%) or extreme risk (n=20;8%) for cataract formation as a result of
accumulated occupational radiation exposures. Less than 30% of respondents believed that
they were either at no risk (n=6;2%) or only minimal risk (n=72;27%). Fifty nine (22%)
respondents indicated that they did not have sufficient knowledge to estimate their risk. Almost
half of the respondents (n=120;45%) reported having no or minimal awareness that ionizing
radiation may contribute to cataractogenesis; almost three-quarters of respondents
(n=197;74%) reported having no or minimal awareness that ICRP annual dose limits exist.
Most respondents (n=147;56%) were categorized as using low amounts of fluoroscopy/week
(≤300 seconds), 78 respondents (30%) as using moderate amounts (301 to 599 seconds
/week), and 39 respondents (15%) as using high amounts (≥600 seconds/week). Although
most reported that they always use leaded gowns (n=227;86%) and thyroid shields
(n=161;61%). 91% of respondents (n=234) indicated that they never use radio-protective
eyewear. Of those who indicated that they had never used radio-protective eyewear, the most
commonly cited reasons were that the institution did not supply them, that the respondent did
not know where to purchase them, and that the respondent was unaware of a possible
cataract risk. The association between perceived risk and awareness was statistically
significant (p<0.001).
Conclusion: This study demonstrated a large information deficit among orthopaedic surgeons
with respect to their awareness of the potential risk of cataractogenesis due to radiation
exposure and of the existence of dose limits.
70: On-Line Vs Paper Format Learning: Identifying Inflammatory Arthritis Early:
Randomized Control Trial
Veronica Wadey, ON; Heather McDonald-Blumer, ON; Alfred Cividino, ON; Jean Wessel, ON;
Deborah Kopansky-Giles, ON; David Levy, ON; Jodi Herold, ON; Douglas Archibald, ON
Purpose: The purpose of this study was to determine whether medical residents learning by
case simulation using on-line learning technology (OLT) on “sore hands, sore feet”, would
have a greater improvement in knowledge, skills and satisfaction in learning how to identify
patients with early-stage inflammatory arthritis than medical residents using a paper format
(PF) only.
Method: A randomized control trial (RCT) was conducted with family medicine and
rheumatology residents followed by focus group interviews. An orientation session with
pre/post test questionnaires and analyses was completed. Thirty-one subjects completed the
“Sore Hands, Sore Feet” (SHSF) learning module and were randomized into either the OLT or
PF groups. Twelve residents completed the module online (OLT - experimental group) and 19
completed the paper-based format (PF - control group). Each of these learning methods
underwent full content review prior to this trial. Data was analyzed based on: Time 1 (PreModule), Time 2 (Post-Module) and Time 3 (3 month Follow-up). The OLT group did not
complete the Pre-Module assessment; however 19 in the paper-based group did so. Repeated
Measures ANOVA was used to assess the extent to which there was learning in the PF group
from Time 1 to Time 2. One-way ANOVA was used to assess the effect of learning format on
Post-Module test scores. A separate Repeated Measures ANOVA was run to determine the
effect of format (OLT versus PF) on retention from Time 2 to Time 3. Two focus groups were
conducted
Results: No significant difference among family medicine and rheumatology residents in either
the online (OLT) and paper format (PF) groups (means of 2.60 out of 4 for the OLT group; 2.76
out of 4 for the PF) existed at the beginning of the study. There was a significant increase in
scores from Time 1 (11.21/16; SD=2.30) to Time 2 (12.79/16; SD=2.20) for the PF group. At
time 2 and time 3, there were no differences in scores between the PF and OLT groups
[provide values for the OLT group.] There was a small but statistically significant decrease in
scores from Time 2 to Time 3 for BOTH groups (Post-test mean scores equaled 12.58 out of
16; SD=1.78 and Follow-up mean scores equaled 11.97 out of 16; SD=2.09). Findings from
the focus group interviews suggested that all residents found the SHSF module to be very
informative. Residents learned how to appropriately refer a patient to a rheumatologist and
carried out this act during clinical encounters. This may suggest that knowledge transfer was
occurring.
Conclusion: Overall, the residents learned from both OLT and PF methods and found the
SHSF module very informative and were able to retain similar amounts of knowledge
regardless of method for learning used. A preference for the online learning resources was
expressed by all residents.
71: Selecting Applicants for Residency Training Programs: Can We Predict Their
Success?
Raman Mundi, ON; Harman Chaudhry, ON; Cheromi Sittambalam, ON; Susan Reid, ON;
Brad Petrisor, ON; Mohit Bhandari, ON
Purpose: The selection criteria used by residency training programs are varied but typically
aim to identify individuals who will excel in their chosen specialty. This meta-analysis assesses
common selection criteria used by residency programs for their ability to predict future
performance during residency.
Method: Three medical databases (MEDLINE, Embase, and PsycInfo), as well as PubMed
and reference lists, were screened to select North American studies in all specialties. The
following measures of medical student performance were assessed: (1) interview performance,
(2) GPA, (3) board exam scores, (4) match list ranking, (5) AOA membership, (6) dean’s letter,
(7) reference letters, (8) research experience, (9) medical school prestige, and (10) class rank.
A meta-analysis of Pearson’s correlation coefficients was performed to assess the relationship
between these characteristics and the following measures of residency performance: (1) Board
certification and in-training exam scores (objective measures of cognitive performance); and
(2) Faculty and rotations evaluations (subjective measures of cognitive and behavioural
performance).
Results: From over 2237 potential studies, 32 studies satisfied inclusion criteria. Board exam
score (r=0.52, p<0.001) and match list ranking (r=0.59, p=0.002) were strong predictors of
objective success in residency, while medical school grades (r=0.30, p<0.001) were
moderately correlated to objective success. Although weak in magnitude, medical school
grades (r=0.25, p<0.001) and interview performance (r=0.17, p=0.005) were the only
characteristics that correlated significantly with subjective measures of success. Membership
in AOA, dean’s letters, reference letters, research experience, medical school prestige, and
medical school rank failed to predict resident success due to statistical insignificance or
insufficient data for analysis.
Conclusion: Our findings suggest that applicants with higher board exam scores and higher
overall match list ranking tend to have better performance on objective measures of success
(exams) during residency training.
72: The Apple Doesn't Fall Far From the Tree: Why Do We Teach the Way We Do, and
How Can We Do it Better?
Stephen M Mann, ON; Gurjit Sandhu, ON
Purpose: To examine attitudes and beliefs among residents and attending surgeons regarding
effective and ineffective methods of teaching, and to compare these responses to educational
literature. Specifically, the use of role modelling and shame-based learning were addressed.
Method: Responses from residents involved in a workshop entitled "Teaching residents how to
teach" were compiled over two years and mapped to a literature-based grid of effective and
ineffective teaching strategies. Additionally, based on data collected from a pre-survey
questionnaire, attending staff from the Department of Surgery were interviewed regarding their
teaching habits and strategies, and their responses qualitatively reviewed and compared to the
literature.
Results: Role modelling was consistently mentioned by residents as an effective teaching
strategy. It was also widely used by attending physicians, particularly to convey non-medical
expert CanMEDS roles such as communicator and collaborator. Many staff, however, feel that
role modelling can be performed subconsciously, leading to arguably inferior translation.
Shame-based learning has been a part of surgical education for centuries, but has been
demonstrated to be an ineffective means of knowledge transfer. However, the clinical
applicability of case-based learning, such as what happens in typical morning trauma rounds,
is appreciated and relevant. Additionally, there is wide belief among staff surgeons, and some
residents, that the motivation provided by being on the "hot seat" inspires greater academic
efforts.
Conclusion: Role modelling is an effective means of teaching many of the "softer" or nonmedical expert CanMEDS roles, but it must be consciously employed to be of greatest value.
Shame-based learning in the traditional sense has many undesired effects and is not an
effective teaching strategy. Many aspects of it, however, such as case-based applicability and
immediate feedback, can be applied to relevant teaching methods.
73: The OSCORE (Ottawa Surgical Competency Operating Room Evaluation) - A
Validated Tool to Evaluate Surgical Competence
Wade T Gofton, ON; Nancy L Dudek, ON; Fadi Balla, ON; Stan Hamstra, ON; Timothy J
Wood, ON; Steven R Papp, ON; Shay Seth, ON
Purpose: Surgical training programs are responsible for ensuring the competency of their
graduates. The formal assessment of a surgical trainee’s ability to safely perform surgical skills
is limited to a small portion of the In-training Evaluation Report. Most surgical trainee
assessment is based on measures of knowledge (i.e. ‘knows how’). Whereas, the assessment
of a trainee’s competence to actually do (i.e. ‘shows how’) the various surgical procedures is
limited to a small portion of the In-training Evaluation Report. Most evaluation tools validated to
assess surgical procedures usually only assess specific technical procedures. This study
involved the assessment of a tool designed to evaluate the competence of a trainee to perform
an entire surgical procedure regardless of procedure type.
Method: The initial tool was developed by key stakeholders, piloted and in Orthopedic surgery
and named the OSCORE. It is a 9-item tool with each item rated on a scale where the
maximum score is defined as competent for independent practice. In this study the OSCORE
was used in the in the University of Ottawa’s General and Orthopedic Surgery Residency
Programs where staff surgeons evaluated residents on ten common procedures. Post-study
focus groups were conducted.
Results: Thirty-four surgeons completed 163 assessments on 37 residents. An ANOVA
analysis demonstrated an effect of postgraduate year (PGY). Post hoc analysis found that total
scores for PGY (1-2) were significantly different from PGY 3 (p<0.001) and PGY 3 from PGY
(4-5) (p < 0.05). Analysis of the qualitative data indicated the scale was practical and useful for
staff and residents.
Conclusion: This novel evaluation tool successfully discriminated between junior and senior
residents and identified surgical competency across various PGY trainee levels regardless of
procedure type. This suggests that the OSCORE is valid for the assessment of trainee
operative competency.
74: The University Of Toronto Competency Based Curriculum’s “Orthopaedic Boot
Camp”: Examining Retention Rates For Skills Taught Through An Intensive LaboratoryBased Surgical Skills Course
Markku T Nousiainen, ON; Ranil Sonnadara, ON; Oleg Safir, ON; Shawn Garbedian, ON;
Peter Ferguson, ON; William Kraemer, ON; Benjamin Alman, ON; Richard Reznick, ON
Purpose: Prior publications on the University of Toronto Competency Based Curriculum’s
(CBC) “Orthopaedic Boot Camp” have shown compelling data that an intensive, laboratorybased course at the beginning of residency training can be highly effective at teaching and
developing targeted technical skills. We present data from three groups of residents which
examine the retention rates for skills taught in this manner.
Method: Three groups of residents were assessed in their ability to perform basic surgical and
medical technical skills and the basic principles of AO fracture fixation. The first group (CBC)
started their training with a month long ”boot camp” course in basic technical skills. The other
two groups were regular stream Junior (JR) and Senior (SR) residents, whose training included
no such course. Performance on targeted technical skills was examined using an OSATS
examination up to 18 months after the completion the skills course for the CBC group and up
to 19 months after the onset of training for the JR group.
Results: Data revealed that skill retention rates for the CBC group were excellent (mean GRS
scores remained at 4.3 even 18 months after the course). There were also no significant
performance differences between the CBC and SR groups (mean GRS scores were 4.3 and
4.4). Both the CBC and SR groups performed significantly better than the JR group (mean
GRS score 3.7; F[2,15]=12.269, p<0.001).
Conclusion: We conclude that an intensive, laboratory-based course is an extremely effective
mechanism for teaching targeted technical skills and that skills taught in this manner can have
excellent retention rates. Furthermore, it seems that an early focus on technical skills allows
junior residents to perform at the level of senior residents much earlier in training for targeted
tasks. Anecdotal reports from faculty suggest that the skills course has greatly enhanced
capacity of our CBC residents throughout their training. This training model has now been
instituted for all incoming orthopaedic residents in the Division of Orthopaedic Surgery in
Toronto.
75: A Survey of Canadian Orthopaedic Surgeons’ Current Approach to Post-operative
Fracture Radiographs, and Their Attitude Toward a Simplified Protocol
Presenter: Ted V Tufescu, MB
Purpose: To determine Canadian Orthopaedic surgeons’ current protocol for early postoperative radiographs of stable, internally fixed fractures, and their willingness to adopt a
simplified protocol.
Method: Members of the Canadian Orthopaedic Association were invited to participate in an
electronic survey via email. Subjects were presented with five fractures: femur and tibia midshaft fractures treated with intra-medullary nails, and forearm, humerus and ankle fractures
treated with compression plating. The survey documented selected demographic data, the
surgeon’s current post-operative protocol for radiographs, and explored whether surgeons
would consider a simplified protocol. Results were analyzed and means were reported.
Results: Eight hundred and twenty two invitations were emailed, of which 400 were opened.
Two hundred and forty three surgeons followed the link and completed the survey. The
majority of surgeons were practicing in Canada (91%), managed some trauma (91%), but were
not dedicated trauma specialists (82%). Surgeons of all experience levels were equally
represented with 23% having zero to five years experience, 23% five to 10 years, 26% 10 to
20 years and 29% with over 20 years of experience. Sixty six percent of respondents currently
acquire immediate post-operative radiographs for femur and tibia fractures treated with
intramedullary nails, and 62% repeat them at two weeks. Fifty one percent of respondents
currently acquire immediate post-operative radiographs for forearm, humerus and ankle
fractures treated with open reduction and internal fixation, while 69% repeat them at two
weeks. Of respondents who currently acquire radiographs, 33% would consider foregoing
immediate post-operative radiographs after intramedullary nailing of femur and tibia fractures,
while 25% would consider foregoing these at two weeks. In the group currently acquiring
radiographs, 58% would consider foregoing radiographs immediately after open reduction and
internal fixation of forearm, humerus and ankle fractures, while 24% would consider foregoing
these at two weeks.
Conclusion: This survey demonstrates that a large portion of Canadian Orthopaedic surgeons
already do not acquire radiographs until six weeks after internal fixation of selected fractures,
and a large portion of those who do, would consider a change in practice to a simplified
protocol. These findings support investigating the safety and cost efficiency of a simplified
post-operative radiographic protocol.
76: Implant Choices in the Treatment of Tibial Open Fractures: Minimizing the Rate of
Infection
Sebastian R Rodriguez-Elizalde, ON; Omar Desouki, ON; Bheeshma Ravi, ON; Richard
Jenksinon, ON
Purpose: To compare the infection rates of two different surgical techniques: intra-medullary
tibial nailing versus plating.Orthopaedic fracture management has evolved in both surgical
approach and technique over the last twenty years. A respect for soft tissues, better
orthopaedic implants and minimally-invasive techniques (MIS) have helped improve union
rates in open tibial fractures. However, little has been studied in the modern era to determine if
these techniques improve infection outcomes in open fracture patients. We hypothesized tibial
intra-medullary nailing vs plating (open or MIS) in the management of open fractures would
result in less complications (deep infections), if the fracture pattern were amenable to either
surgical technique.
Method: Our institution has an ongoing orthopaedic trauma database, which collects various
parameters on all patients prospectively. The database was reviewed to identify all open tibial
fractures over the last 10 years at our institution. All patients were treated by fellowship trained
orthopaedic trauma surgeons or fellows in an academic setting. 220 were initially identified
according to OHIP (Canadian provincial universal health insurance) coding. After reviewing all
charts and radiographs, we eliminated patients who were deceased (as a result of their initial
trauma), had isolated ankle or fibular fractures, or were treated definitively by other methods
(ex- fix). This left us with a cohort of 135 patients to analyze. All radiographs were reviewed
twice: once by an attending orthopaedic surgeon and once by a trainee (resident or fellow).
The initial fracture patten was analyzed to determine if IM nailing was an option in all patients
treated via plate fixation.
Results: Of the 135 open tibial fractures, 88 were definitively treated by IM nail fixation, and 47
were plated. In total, of the 18 patients that went on to develop documented deep infection,
eight were treated by IM nail, and ten by plate fixation. We then reviewed all initial fracture
pattern radiographs to determine if an IM device could have been used as definitive fixation
instead of plating, using strict inclusion criteria. This review demonstrated that ten of the 47
patients treated definitively with plate fixation could have been nailed (21.3%). Of these, 3
(30%) developed deep infection.
Conclusion: In conclusion, we demonstrated that most open tibial fractures are treated via IM
nail fixation (65.2 % vs 34.8%) when compared to plate fixation. Ten percent of those treated
with IM nails developed infection, compared to 27% of those with plates. Of the 47 patients
treated with plating, 10 could have been treated with an IM device, and of those 3 (30%) went
on to develop deep infection. This demonstrated rate of infection is three times higher than
those treated via IM nailing. Overall implant choice is guided by many factors, many not in a
surgeon’s control. However, if there is an option to use an IM device, it should be strongly
considered.
77: Management of Tibial Plateau Fractures in Patients 60 Years and Older with Staged
Total Knee Arthroplasty
Peter Dust , SK; William Dust, SK
Purpose: In older patients treatment of tibial plateau fractures with ORIF, total knee
arthroplasty (TKA) acutely or as salvage have proven unpredictable with high complication
rates. The purpose of this study is to report the results of patients over 60 managed with a
staged protocol of TKA.
Method: Patients are placed in a hinged rehabilitation brace. Immediate range of motion
(ROM) with full weight bearing is encouraged. Hospital admission is avoided when possible.
After six weeks the brace is weaned. Twelve weeks post fracture the brace is discontinued and
full activities are encouraged. Six months post fracture all are offered a TKA. If TKA is declined
patients are followed. Follow-up (FU) assessment included a Knee Society score and
radiographs which included a three foot lower extremity film.
Results: Twenty three patients were managed with this protocol. One patient was lost to FU
after three months and not further included. Continued Nonoperative Management. Fourteen
patients, average FU 28 months, declined TKA. There were 11 Schatzker II and three
Schatzker V or VI fractures. The average amount of joint depression was 13 mm (range 0-19).
The patient with no joint depression (Schatzker VI) had an articular gap of 10 mm. The
mechanical axis ranged from 10 degrees varus to 15 degrees valgus. The average knee score
was 81. The average ROM was 5-120 degrees flexion. TKA Eight had a posterior stabilized
TKA. The decision to proceed with TKA was made at an average of five months post fracture
(range 3-7 months). The average joint depression was 23 mm (range 10-32), the average
preop knee score 46. At 21 months average FU the average knee score was 76. The average
preop ROM was 10-110 degrees, postop 5-105 degrees. All knees coming to TKA had valgus
alignment, the average preop mechanical axis 13 degrees (range 4-27). Postop average two
degrees varus (range 0-4). Detailed surgical notes included a subjective assessment of the
degree of difficulty compared to a routine TKA. Four knees, all Schatzker II fractures were
considered only slightly more difficult. These all had healed fractures with a central defect that
either did not need management or were managed with morsellized autograft. No augments or
stems were required. In the remainder three metal augments and four stems were used. Two
were considered difficult. One a Schatzker II fracture with 27 degrees mechanical valgus (FU
knee score 82, 5-115 degrees flexion). The other a high energy Schatzker VI with 18 degrees
mechanical valgus with extensive malunited bone that needed to be removed (FU knee score
98, 5-115 degrees flexion). No complications have occurred in the TKA group.
Conclusion: Staged TKA is a reasonable treatment option for these difficult fractures and is
capable of producing good results with a low complication rate. Health care costs are
minimized by avoiding CT scans, minimizing or avoiding hospital admissions and performing
surgery only on patients who demonstrate a need for it.
78: Management of Unstable Proximal Femoral Fractures with Reverse Locked Distal
Femoral Plates- Our Experience in 21 Patients
Pankaj Mahndra, IN; Rajnish Garg, IN; Harpal Singh Selhi, IN
Purpose: The optimal management of unstable proximal femoral fractures is controversial. In
this prospective study, we assessed the outcomes of reverse distal femoral locked plates for
treatment of comminuted unstable proximal femoral fractures
Method: From June 2005 to April 2009, 21 patients with unstable proximal femoral fractures
that were assessed to be difficult to nail were managed with reverse -distal femur plates, which
included (1) subtrochanteric fractures with extension into the piriform fossa, (2) short skeletons
with narrow femoral canals, (3) adolescents with open physes, (4) severely bowed or deformed
femurs and (5) Indian proximal femur which are too small to accept a nail. These patients were
enrolled in this study. There were eight females and 13 males, with a median age of 52 years
(range, 18-65 years). The average follow-up period was 24 (range, 12-32) months. The
outcome was assessed on the basis of bony union, neck shaft angle, any residual deformity,
fixation failure, metal work failure, infection, limb length discrepancy and return to pre injury
functional status.
Results: Union was achieved in 18 out of 21 patients. The average time to union was 6
months (range 3- 12 months). We had on implant breakage, which was revised for fixation and
bone grafting and the fracture proceeded to union at 9 months post injury .One of our cases
had loosening of proximal screws but the fracture united in 3 months in some varus with
shortening. Another patient had shortening of more than 1.5 cms, the cause of which was
varus mal reduction at the fracture site. One of the patients with the deformity complained of
significant hip pain. Superficial infection occurred in one patient which healed after
debridement and a short course of I- V antibiotics.
Conclusion: Taking into consideration the simple surgical technique, good healing rate and
minimum complications we strongly recommend the use of reverse locked distal femoral plates
in carefully selected patients
79: Operative versus Non-operative Treatment of Acute Dislocations of the Acromioclavicluar Joint: Results of a Multi-centre Randomized, Prospective Clinical Trial
Stéphane Pelet, QC; Michael D McKee, ON; Canadian Orthopaedic Trauma Society (COTS),
ON
Purpose: Purpose: The optimal treatment for acute dislocation of the acromio-clavicular (AC)
joint remains unclear. Both surgical repair and non-operative treatment have been advocated,
but prior randomized trials did not reveal any significant differences between groups. However,
these studies used inferior surgical techniques and surgeon-based or radiographic outcome
measures. We sought to perform a randomized clinical trial of operative versus non-operative
treatment of acute AC joint dislocations using modern surgical fixation and patient-based
outcome measures.
Method: Methods: We performed a prospective, multi-center, randomized clinical trial
comparing operative repair with hook plate fixation versus non-operative treatment for acute (<
three weeks old) complete (Grades III, IV, V) dislocations of the AC joint. The primary outcome
measure was the Disabilities of the Arm, Shoulder, and Hand (DASH) score at one year postinjury. Assessment also included a complete clinical assessment, the Constant score, the SF36 score, and a radiographic evaluation at 6 weeks, and at three, six, twelve, and twenty-four
months.
Results: Results: Eighty-three patients were randomized (operative repair 40, non-operative
treatment 43). There were no demographic differences between the two groups (operative:
male/female 36/4, non-operative 42/1, p=0.279, mean age operative group: 38.7 years, nonoperative group: 37.3 years, p=0.778, dominant arm: operative group 24, non-operative 26,
p=0.823, smoker: operative group 10, non-operative 16, p=0.338). The mechanisms of injury
were similar between the two groups. DASH scores (a disability score – lower score is better)
were significantly better in the non-operative group at six weeks (operative 46, non-operative
31, p=0.007), three months (operative 28, non-operative 16, p=0.01), and six months
(operative 15, non-operative 8, p=0.03). There were no significant differences between the
groups at one (operative 10, non-operative 6, p=0.189), or two (operative 3, non-operative 4,
p=0.893) years post-injury. Similar values were seen for Constant scores at six weeks
(operative 52, non-operative 75, p=0.000), three months (operative 69, non-operative 85,
p=0.001), six months (operative 83, non-operative 92, p=0.001) one year (operative 90, nonoperative 94, p=0.006) and two years (operative 93, non-operative 93, p=0.770). Additionally,
the re-operation rate was significantly lower in the non-operative group (p<0.05).
Conclusion: Discussion: Hook plate fixation is not superior to non-operative treatment for the
treatment of acute, complete dislocations of the AC joint. The non-operative group had better
early scores, although both groups improved from a significant level of initial disability to a
good or excellent result (mean DASH score 3, mean Constant score 93) at two years. At the
present time, there is no clear evidence that operative treatment with hook plate fixation
improves short or long-term outcome for complete AC joint dislocations.
80: Radiographic Outcomes of Closed Diphyseal Femur Fractures Treated with the
SIGN Nail
Sasha Carsen, ON; Sam Park, ON; David Simon, ON; Robert Feibel, ON
Purpose: The burden of orthopaedic trauma in the developing world is significant and
disproportionate, both in health and economic terms. The Surgical Implant Generation Network
(SIGN) has developed and made available to surgeons in resource-limited settings a low-cost
intra-medullary prosthesis for use in the treatment of fractures of the femur and the tibia, with
the prosthesis and necessary tools donated. Despite the clinical success of the SIGN Nail, with
more than 50,000 surgeries performed, there has been very little research examining
outcomes. Our primary purpose was to examine the post-operative radiographs of closed
diaphyseal femur fractures treated with the SIGN Nail to assess for alignment. Our secondary
goal was to assess the functionality and robustness of data in the SIGN database.
Method: A retrospective review was undertaken of patients treated with the standard SIGN
Nail, which at the time of the study totaled 32,362. Further inclusion criteria included the
treatment of a diaphyseal femur fracture. Exclusion criteria included open fractures and those
without post-operative radiographs. A random number generator was used to randomly select
500 cases for analysis, and the following information was recorded: Location of the fracture
within the diaphysis, fracture classification (AO/OTA classification), degree of comminution
(Winquist classification), and patient demographics. Measurements of alignment were then
made based on the Antero-Posterior and Lateral radiographs, with mal-alignment defined
conservatively as deformity in either the saggital or coronal plane greater than 5 degrees. The
quality of radiographs for each case was graded based on adequacy for visualization of the
fracture, the femur, and the ability to measure alignment in orthogonal planes.
Results: The incidence of mal-alignment in post-operative radiographs was found to be 8.4%.
More than 90% of reviewed radiographs were of acceptable or good quality. Degree of
comminution was found to be an independent predictor of angulation and mal-alignment.
Conclusion: The incidence of malalignment in femoral fractures treated with the SIGN Nail
closely approximated the incidence previously reported in the literature for a North American
trauma centre. This is an encouraging finding, and provides support for the continued and
expanded use of the SIGN prosthesis throughout the developing world. Additionally, the SIGN
database, which is populated by data submitted by SIGN surgeons around the world, was
found to be a satisfactory resource for the purpose of retrospective research
81: The Evaluation of a New Measure for Assessing Healing in Lower Extremity
Fractures
Brad Petrisor, ON; Mohit Bhandari, ON; Scott M Wasserman, CA; Nicole Yurgin, CA; Ricardo
Dent, CA; Shelia Sprague, ON
Purpose: The recently developed Functional Index for Intramedullary Nailed Tibial Fractures
(FIX-IT) measure provides a standardized approach to assess weightbearing and pain in lower
extremity fractures. The objective was to evaluate inter-rater reliability and construct validity of
the FIX-IT measure.
Method: A cross-sectional study of 50 patients with lower extremity fractures across different
stages of healing was conducted in 2009. This was a convenience sample and patients were
recruited from a single site in Canada. The clinicians were asked to assess whether the items
of FIX-IT were ‘essential’, ‘useful’, or ‘not needed’ to provide preliminary construct validity of
the FIX-IT measure. Inter-rater reliability of the raters’ scores was assessed using inter-class
correlation coefficients (ICCs). Convergent validity was evaluated by Pearson’s correlations
between FIX-IT and the SF-36 physical component summary, physical function subscale, and
role-physical subscale scores.
Results: The overall inter-rater reliability for the total FIX-IT score was 0.879 (95% CI, 0.8280.921). All of the clinicians rated each of the four procedures as either ‘essential’ or ‘useful’.
The correlations between the FIX-IT score and the SF-36 ranged from: 0.682 to 0.770 for the
physical component summary score, from 0.681 to 0.758 for the physical function subscale,
and from 0.677 to 0.786 for the role-physical subscale.
Conclusion: The FIX-IT score had high inter-rater agreement across multiple examiners and
correlates with the physical scores of the SF-36. Clinicians rated all of the procedures
evaluated in FIX-IT as useful in measuring healing for tibia fracture patients.
82: TRial to Evaluate UltraSound in the Treatment of Tibial Fractures (TRUST): A Pilot
Study
Brad Petrisor, ON; Jason W Busse, ON; TRUST Investigators, ON; Mohit Bhandari, ON
Purpose: Tibial fractures are associated with a prolonged recovery period. While results of a
number of small randomized trials have suggested that low-intensity pulsed ultrasound
(LIPUS) accelerates fracture healing, inferences about functional gains remain weak. The
purpose of the present pilot randomized trial was to assess the feasibility of a definitive trial to
determine the effect of LIPUS on functional and clinical outcomes in operatively treated tibial
shaft fractures.
Method: We conducted a multicentre, blinded pilot randomized trial of 51 skeletally mature
adults with operatively managed tibial fractures who were treated with either LIPUS or a deactivated LIPUS device. The goals of our pilot study were to determine recruitment rates in
individual centers, determine investigators’ ability to adhere to study protocol and data
collection procedures, determine our ability to achieve close to 100% follow-up rates, and
determine the degree to which patients were compliant with treatment. Our primary outcome
measure was physical function as measured by the Short Form-36 physical component
summary (SF-36 PCS) score. Our secondary outcomes included the Health Utilities Index-III
(HUI-III), the Short Musculoskeletal Functional Assessment (SMFA) measure, time to
radiographic healing, rates of malunion and nonunion, and rates of secondary procedures
(operative and non-operative).
Results: A total of 51 patients were randomized; 23 to LIPUS and 28 to a sham device. Our
overall rate of recruitment was approximately 0.8 patients per month, and site investigators
successfully adhered to the study protocol and procedures. Forty-three patients (84%)
completed one year of follow-up. Patient compliance with use of the ultrasound device was
high, with 76% (n=39) demonstrating full compliance and 24% (n=12) demonstrating greater
than 50% compliance. Both SF-36 PCS scores (mean difference 6.6, 95% confidence interval
0.1 to 13.0) and HUI-III scores (mean difference 0.20, 95% confidence interval 0.01 to 0.39)
demonstrated a significant advantage in favour of LIPUS at the 6-month follow-up (p=0.046
and p=0.035 respectively). Other outcome measures were not significant between treatment
arms. Tibia fractures at risk, demonstrated delayed functional recovery versus fractures not at
risk, and this difference was significant at 9 and 12 months of follow-up (p<0.001 and p=0.03
respectively).
Conclusion: Our pilot study supports the feasibility of a definitive trial. A pivotal trial of 500
patients to resolve uncertainty around our pilot trial estimates of function gains, radiographic
fracture healing, and reoperations is currently underway.
83: Unstable Chest Wall Injuries: A National Trauma Databank Analysis of Flail Chest
Injuries
Niloofar Dehghan, ON; Charles de Mestral, ON; Michael D McKee, ON; Avery Nathens, ON
Purpose: Rib fractures are common injuries and occur in 39% of patients with blunt chest
trauma. Up to 15% of these cause a flail chest, and lead to chest wall instability. Chest wall
instability can lead to severe pulmonary restriction, need for intubation and mechanical
ventilation, and high rates of pneumonia, barotrauma, sepsis, ICU stay and death. These
injuries are commonly treated non-operatively with mechanical ventilation and pain
management as needed; however, the literature suggests better outcome with surgical fixation.
Our goal was to evaluate the current practices, morbidity, and mortality of patients with flail
chest, to aid in development of an interventional trial evaluating surgical fixation.
Method: The National Trauma Databank (the largest aggregation of US/Canadian trauma
registry), was used for retrospective analysis of the injury patterns, management and clinical
outcomes associated with flail chest injuries. Patients with a flail chest injury admitted from
2007 to 2009 were included for analysis. Outcomes include treatment with surgical fixation or
epidural catheter use; number of days on mechanical ventilator; days in ICU; days in hospital,
rates of pneumonia; tracheostomy; chest tube placement; and death.
Results: In total 354,945 adults with ISS>9 were admitted to 199 trauma centers from 20072009. Flail chest was identified in 3467 patients. The average age at time of injury was 52
years, with 77% male, and 33% female. The mean ISS was 31, and the most common
mechanism of injury (79%) was motor vehicle collision. Bad head injury was present in 15% of
patients (defined as AIS>3 or GCS-motor <5), while 54% had lung contusions. Treatment
practices included epidural catheter use in 8%, and surgical fixation of the chest wall in 1% of
patients. Mechanical ventilation was required in 59%, for an average of 12.1 days. ICU
admission was required in 82% of patients, for an average of 12 days. Mean length of hospital
stay was 16.6 days. Chest tubes were utilized in 44%, and 21% of patients required a
tracheostomy. Complications included pneumonia 21%, ARDS 14%, sepsis 7%, and death in
16% of the population. Due to the low prevalence of patients treated with surgical fixation or
epidural catheter use, statistical analysis comparing them to patients who did not receive these
interventions was not performed.
Conclusion: Patients who have sustained a flail chest have significant morbidity (ICU
admission 82%, mechanical ventilation 59%, chest tube 44%, tracheostomy 21%, ARDS 14%,
sepsis 7%), and high rate of mortality (16%), with current non-operative treatment methods.
Prior small randomized trials have suggested dramatic improvements with surgical fixation of
these injuries, although this practice is neither widely accepted nor practiced in North America,
with only 1% of flail chests being surgically treated. Based on this study, we have initiated a
multi-center, randomized trial of surgical fixation versus non-operative care for trauma patients
with flail chest injuries.
84: Using a Checklist Improves Agreement between Radiologists and Orthopaedic
Surgeons about Hip Fracture Healing
Brad Petrisor, ON; Mohit Bhandari, ON; Olufemi Ayeni, ON; Simrit Bains, ON; Rajesh
Chakravertty, ON; Meg Chiavaras, ON; Hema Choudur, ON; Naveen Parasu, ON; Sheila
Sprague, ON
Purpose: The assessment of fracture healing following intertrochanteric fracture fixation is
highly variable with no validated standards. The purpose of the present study was to determine
1) the reliability of intertrochanteric fracture healing assessment and 2) the assessment of a
novel radiographic scoring system for hip fractures.
Method: A panel of 6 reviewers (3 musculoskeletal radiologists, 3 orthopaedic surgeons)
assessed fracture healing for 150 cases of intertrochanteric fractures at two separate time
points with a time lapse of 4 weeks. Reviewers, blinded to the date of imaging, assessed
overall healing from two orthogonal radiographs for each patient at a single time point. Patients
were at various stages of healing. Reviewers also scored each fracture on a scale from 10 to
30 using a Radiographic Union Scale for Hip (RUSH) form. This involved the assessment of
cortical bridging, and the disappearance of cortical fracture lucency. Two trabecular indices
were also scored, one based on consolidation and the other using fracture line disappearance.
The quantity of callus formation was also scored.
Results: Overall, inter-rater agreement for the impression of fracture healing between reviewer
groups was fair [intraclass correlation coefficient (ICC) = 0.34, 95% confidence interval (CI):
0.11-0.52]. Agreement within the radiologist group was higher than the surgeon group (0.60 vs.
0.24). Use of the RUSH score improved overall agreement between groups to substantial
(ICC=0.66, 95% CI: 0.53-0.75). Intra-rater agreement was almost perfect for fracture healing
(ICC=0.84, 95% CI: 0.74-0.91) and substantial for RUSH score (ICC=0.69, 95% CI: 0.35-0.84).
Reviewers’ subjective assessments of healing seemed to be highly correlated with the overall
RUSH score and their assessment of healing of the medial cortex bridging (Pearson’s
correlation (r) = 0.72 and 0.53 respectively). The medial cortex bridging was especially
correlated with healing among radiologists versus surgeons (r=0.53 vs. 0.42).
Conclusion: The RUSH radiographic score achieved higher inter-observer agreement among
reviewers than subjective assessments. Higher RUSH scores and healing of the medial cortex
correlated with subjective assessment of overall fracture healing. Studies evaluating
agreement with a temporal sequence of the radiographs and the addition of clinical information
may enhance agreement between reviewers.
85 A Finite Element Contact Analysis of Axisymmetric and Anatomical Radial Head
Hemiarthroplasty
G Daniel G Langohr, ON; Ryan Willing, ON; John B Medley, ON; Graham JW King, ON;
James A Johnson, ON
Purpose: Radial head (RH) fractures are common and treatment may require the use of a
hemiarthroplasty prosthesis that articulates with natural cartilage at the radiocapitellar and
radio-ulnar joints. Current RH prostheses have been reported to decrease joint contact area
by up to two-thirds, which could contribute to degradation of the natural cartilage. The native
RH is has a complex somewhat elliptical geometry while most current prostheses are
axisymmetric. The purpose of the present study was to compare axisymmetric and
‘anatomical’ RH prosthesis geometries on joint contact area and stress.
Method: A finite element model was developed with a natural capitellum articulating with a
concave RH hemiarthroplasty prosthesis having either an axisymmetric (spherical) or
anatomical (elliptical) geometry. The axisymmetric RH was given a 20.4 mm concave radius
to mimic a commercially available device. The anatomical RH was given maximum radius of
20.4 mm and a minimum radius of 15.7 mm as determined from previous anthropometric
studies. Maximum stress, contact pressure (CP) and contact area (CA) were computed for a
100 N load at a variety of flexion angles and RH rotations.
Results: It was apparent that the natural capitellum surface was not axisymmetric because a
non-circular contact area was generated during articulation with the axisymmetric RH. For the
anatomical RH, the average CA for all RH rotations was 22% larger at 0°, 11% larger at 45°
flexion, but 26% smaller at 75° flexion, relative to the axisymmetric design. With the long axis
of the RH oriented in the M-L direction, the anatomical model reduced the maximum cartilage
stress by an average of 14% at all flexion angles. When the long axis of the RH was oriented
in the A-P direction, the average CP was reduced, but the peak cartilage stress was
increased. Analysis of contact morphology showed this was a result of edge loading as the
small radius of the anatomic RH impinged on the capitellum, which had a larger natural
curvature in the M-L direction.
Conclusion: The results of the present study show that, in comparison to the axisymmetric
design, an anatomical RH hemiarthroplasty can affect CA, and in some positions reduce
average CP & peak cartilage stress. This effect was most pronounced when the RH long-axis
was oriented in the M-L direction. While it appears that an anatomic elliptical RH may
increase contact area relative to an axisymmetric spherical radial head with the elbow in
some angles of flexion and the forearm in some positions of rotation, this was not a consistent
finding throughout all positions analyzed. Further studies are needed to ascertain the effect of
subtle changes in both shape and size of RH prostheses on the load transfer mechanics at
this articulation to determine optimal implant design and in-vivo orientation.
86: Development of a materials-testing fixture to enable asymmetric loading of the
lower limb: An application of in-vivo gait data
Kristyn M Leitch, ON; Trevor B Birmingham, ON; Jacob M Reeves, ON; Robert J Giffin, ON;
Cynthia E Dunning, ON
Purpose: Experimental parameters to test material properties of fixation plates used for
medial opening wedge high tibial osteotomy (HTO) are typically based on static, radiographic
measures of bony alignment and rarely consider in-vivo gait data. During walking, the ground
reaction force (GRF) passes medial to the stance limb, creating a frontal plane lever arm, an
adduction moment, and subsequent asymmetric loading. The purpose of this study was to
design and test a novel multi-axis fixture to be used in a materials testing machine to enable
asymmetric loading of the lower limb in a manner more representative of human gait. Four
hypotheses were tested: (1) distribution of load on the medial side would range considerably
depending on experimental parameters; (2) at a representative frontal plane lever arm of
3cm, distribution of load on the medial side would be approximately 60-75%; (3) coefficients
of variation (CoV) for load distribution measurements obtained within a single testing session
(repeatability) would be ≤2%; and (4) CoV for measurements obtained from separate testing
sessions completed within and between test days (reproducibility) would be ≤ 5%.
Method: Three-dimensional kinematics and kinetics collected from 166 patients with medial
compartment knee osteoarthritis before and after high tibial osteotomy were used to identify
representative values for the frontal plane lever arm about the tibiofemoral joint, ground
reaction force, and tibiofemoral angles. A fixture was designed and fabricated based on these
data and used in a materials testing machine with a pressure measurement system to
quantify the distribution of applied loads between medial and lateral contact surfaces of
proximal tibia and distal femur sawbones. First, the change in distribution of medial-lateral
compartment loads was evaluated using four lever arms, the corresponding angles between
the tibia and GRF, and a compressive force of 900N (the approximate mean frontal plane
GRF from the in vivo gait data). Then, reliability of load distribution was tested by repeating
measurements using a 3cm lever arm (the mean frontal plane lever arm from the in vivo data
24 months post-surgery).
Results: The change in distribution of loads using lever arms from 1 to 4 cm ranged from
5.55-to-85.06%. The load on the medial side was 70.1%, when using a representative lever
arm of 3cm. Coefficients of variation for repeated measures ranged from 0.66%-to-1.83% for
trials within one test session, was 2.70% for trials between test sessions within one day, and
was 4.88% for trials between days.
Conclusion: Results demonstrate appropriate asymmetric loading and excellent test-retest
reliability. These findings suggest the fixture enables loading of the lower limb in a manner
more representative of walking and will be used for future materials testing of HTO plate
designs.
87: Factors affecting stability of reverse shoulder arthroplasty
Ryan T Bicknell, ON; Allison L Clouthier, ON; Markus Hetzler, ON; Graham Fedorak, ON;
Tim Bryant, ON; Kevin J Deluzio, ON
Purpose: Despite the success of reverse shoulder arthroplasty in improving pain and
function, complication rates remain high with dislocation often being the most common
complication. Although some factors affecting stability of the prosthesis have been studied,
the majority have not been examined in a physiological model that simulates bony geometry
and active muscle loads. Therefore, the purpose of this study was to investigate the effect of
arm position, loading direction, humeral socket constraint, glenosphere diameter, and
glenosphere eccentricity on stability of reverse shoulder arthroplasty as well as the
interactions between these factors.
Method: A custom designed kinematic shoulder simulator was used to examine the force
required to dislocate the prosthesis in a synthetic bone model. The three heads of the deltoid
were modelled using pneumatically actuated cables and a displacing force was applied to the
humeral component using a linear actuator. Several factors were investigated: arm position
(abduction (45 and 60 degrees) and horizontal flexion (-15 and 55 degrees)), loading direction
(anterior, posterior, superior, and inferior), humeral socket constraint (low and high),
glenosphere diameter (36 and 42mm), and glenosphere eccentricity (central and inferioroffset). A randomised half-fraction factorial experiment design was used to investigate the
factors and a six-way ANOVA was performed to determine significance.
Results: Increasing glenohumeral abduction from 45 to 60 degrees resulted in a 30%
increase in force to dislocate the shoulder and changing from a central to an inferior-offset
glenosphere resulted in a 17% increase in force to dislocate (p<0.05). In addition, increasing
humeral socket constraint increased stability if the shoulder was dislocated superiorly (88%
increase), posteriorly (66% increase), or anteriorly (36% increase) (p<0.05), but not inferiorly
(p>0.05). Flexion and glenosphere diameter did not have a significant effect on stability
(p>0.05).
Conclusion: It was determined that greater abduction increases stability of reverse shoulder
arthroplasty. This is likely due to the greater deltoid forces required to achieve this posture,
and, therefore, increasing deltoid tension may be an effective method of improving stability.
Using an inferior-offset glenosphere also increases stability and increased socket constraint
improved stability in all directions except inferior. The interaction between humeral socket
constraint and loading direction, as well as the lack of influence of flexion and glenosphere
diameter, highlights the complicated nature of the instability issue, as well as the importance
of undertaking future research to understand dependencies between factors affecting
stability.
88: Kinematic Comparison Between Gender Specific and Traditional Femoral Implants
Carolyn Anglin, AB; Stefan Karl Saevarsson, AB; Gulshan B Sharma, AB; Spencer
Montgomery, AB; Karen CT Ho, AB; Heiko Ramm, DE; Robert Lieck, DE; Stefan Zachow,
DE; Carol Hutchison, AB; Jason Werle, AB
Purpose: Gender-specific (GS) implants for total knee arthroplasty (TKA) have been
introduced that better suit the female knee shape (Mahfouz 2007). The overall goal is to
increase the success rate of TKA in females. Several recent studies compared the clinical
outcomes between males and females with traditional implants, and between females with
traditional and GS implants. Most of these studies did not find a significant difference between
the implant designs (Song 2011, Kim 2010). However, clinical scores are unable to detect
subtler differences related to patellofemoral (PF) function, which could lead to differences in
patient satisfaction. The industry claims that the design differences should lead to better
patellar tracking in women but, to our knowledge, no in vivo study has been performed that
evaluates what effect GS knees have on PF kinematics. We have developed a unique,
validated protocol that makes this possible (Sharma 2012 ORS).
Method: We imaged 24 TKA subjects. Of these, 2 subjects were bilateral resulting in 15 GS
implants and 11 traditional implants. Static radiographs were taken at 8 different knee flexion
angles, 0°, 15°, 30°, 45°, 60°, 75°, 90° and at max flexion. Subjects put their foot on different
heights of Plexiglas to weightbear at these increments. For each knee flexion angle two
images were taken, with the X-ray source at 10° below horizontal and at horizontal. X-ray
images from two different positions makes matching 3D implant models to the sagittal 2D
images more accurate than a single X-ray image. 3D models of the implants were reverse
engineered using computed tomography imaging. A calibration frame placed around the
subject’s knee made it possible to calibrate the 2D images.
Results: The only significant difference found when comparing the PF kinematics of GS
femoral implants to traditional implants was for PF mediolateral translation at 0° knee flexion
(p=0.02). All other kinematic measures showed large ranges of variability, obscuring any
differences between the two groups. There were no significant differences in tibiofemoral
kinematics.
Conclusion: A more lateral patella at 0° knee flexion for GS implants compared to traditional
correlates with the design of the GS implant which has a more lateral femoral groove in early
flexion. None of the subjects who participated in the study were experiencing severe knee
pain and we can therefore not conclude if one of the designs had better tracking than the
other. The subjects had been operated on by two different surgeons; it could not be seen that
this affected the variability within each group. Both surgeons found it easier to get the correct
anteroposterior/mediolateral dimension ratio with the GS implant. This is the first time PF
kinematics has been compared between these two implant designs. Additional data were
collected for this study which will make it possible for us to analyze the knee kinematics in
more detail and determine the effects different designs have on the patients’ quality of life.
89: Load Transfer at the Distal Ulna Following Simulated Colles’ Malalignment
Masao Nishiwaki, ON; Gillian Greeley, ON; Emily Lalone, ON; Louis Ferreira, ON; James A
Johnson, ON; Graham JM King, ON
Purpose: Distal radial (Colles’) fractures commonly heal with varying magnitudes of
malalignment which often leads to poor clinical outcomes. Abnormal patterns of loading at the
distal radioulnar joint may explain stiffness, pain and arthritis that are commonly seen with
healed angulated and displaced distal radial fractures. The objective of this study was to
examine how varying degrees of isolated and combined distal radius deformities, with and
without triangular fibrocartilage complex (TFCC) injury, affect distal ulnar loading using an in
vitro model. It was hypothesized that distal radial malalignment will increase loading at the
distal ulna, and that the loading would be the lowest with the radius in its native orientation.
Method: A load cell capable of measuring medial-lateral, and anterior-posterior forces was
developed and implanted in the distal ulna, just proximal to the native ulnar head. Active
forearm rotation was achieved in 8 fresh-frozen upper extremities (Age: 71 years (49 to 84
yrs); 6 M; 4 Right) using a joint simulator. A modular implant designed to simulate dorsal
angulation and dorsal translation deformities was attached to the distal radius. Active
pronation and supination motions were simulated with the elbow at 90° of flexion and
kinematic data was recorded using a tracking system. Colles’ type deformities of 0°, 10°, 20°
l translation were simulated and
evaluated both independently and in combinations. Testing was performed before and after
sectioning of the TFCC.
Results: For the native position, there was greater ulnar force with the forearm in supination
relative to pronation (p=0.01). Sectioning the TFCC did not alter the distal ulnar load (p=0.6).
As the magnitude of dorsal angulation and translation of the Colles’ deformities increased,
distal ulnar force up to 165% of the native condition with the most aggressive deformity.
(p=0.008 and p=0.002 respectively). Combined angulation and translation caused a greater
force than either of the conditions in isolation (p=0.002). Sectioning the TFCC resulted in a
reduction in ulnar force for all malalignment conditions; however, this was not significant
(p=0.08).
Conclusion: As hypothesized, this study showed that in a cadaver model simulating distal
radial Colles’ deformities, increasing malalignment of the distal radius increased the forces
measured at the distal ulna. Sectioning of the TFCC released the tethering effects of the
DRUJ ligaments reducing distal ulna loads in the setting of distal radial deformities. This in
vitro data demonstrates the sensitivity of distal ulnar loading to distal radial malalignment and
suggests a possible mechanism to explain, in part, the development of ulnar wrist pain in
patients with healed displaced distal radial fractures.
90: Patella Bone Density Is Lower In Knee Osteoarthritis Patients Experiencing Pain At
Rest
Wadena D Burnett, SK; Saija A Kontulainen, SK; Christine E McLennan, MA; Diane
Wheaton, MA; Carl T Talmo, MA; David J Hunter, AU; David R Wilson, BC; James D
Johnston, SK
Purpose: Osteoarthritis (OA) of the knee is a painful, debilitating joint disease characterized
by cartilage degeneration and changes in the underlying subchondral bone. OA related knee
pain is difficult to treat because the pathophysiology of pain is poorly understood.
Subchondral bone of the patella is innervated, and could be a source of OA-related knee
pain. The objective of this study is to determine if there are measurable differences in patellar
subchondral bone density between knee OA patients experiencing no knee joint pain at rest
and those experiencing severe to extreme pain.
Method: The preoperative knee of 42 patients (17M:25F; mean age: 64± SD10 years) was
scanned using quantitative computed tomography (QCT, Mindways) prior to total knee
replacement and scored for pain using Western Ontario and McMaster Universities Arthritis
Index (WOMAC). Knee pain at rest was defined as moderate to severe pain (score 2-4) in
bed or while sitting/lying down. Patients were subdivided into two groups according to ‘pain’
(N=21, 8M:13F) and ‘no pain’ (N=21; 9M:12F). Patella bone mineral density (BMD) was
assessed using QCT topographic mapping of subchondral density (CT-TOMASD), which
uses surface projections to assess cortical and trabecular subchondral BMD at specific
normalized depths of 0-2.5mm, 2.5–5.0 and 5-7.5mm from the subchondral surface. Total
BMD was evaluated (lateral + medial facets) as well as regional BMD in the superior, middle
and inferior thirds of the lateral facet. We used independent sample t-tests (α<5%, p<0.05) to
compare regional BMD between the ‘pain’ and ‘no pain’ groups using SPSS 18.0.
Results: Total lateral facet density was 16% lower in OA patients with knee pain across the
5-7.5mm depth (‘pain’ 263±77 mg/cm3 K2HPO4; ‘no pain’ 316±84). Inferior density at the
lateral facet was 13% lower at the 0-2.5mm depth (‘pain’ 438±94; ‘no pain’ 504±94), 26% at
the 2.5-5mm depth (‘pain’ 208±75; ‘no pain’ 270±59), and 36% lower at the 5-7.5mm depth
(‘pain’ 187±71; ‘no pain’ 239±66). BMD did not differ between groups at other regions.
Conclusion: The CT-TOMASD imaging technique demonstrated lower regional density in
OA patients with pain at rest. Differences in density at the distal site were approximately five
times greater than calculated precision errors (%CV<7%). These results add to previous
related findings, between pain and bone marrow lesions, which may be related to apparent
BMD. The relationship between clinical pain scores and patellar BMD has not yet been
explored or reported. Decreased lateral facet BMD could also be due to an interaction
between adaptive bone metabolic activity and patellar joint loading patterns. Other relations to
explore are patellar alignment and increased patellar-femoral involvement. The outcomes of
this study provide evidence of a relationship between pain and BMD and may enhance the
understanding of OA pathophysiology and provide new therapeutic targets, such as bone
modifying drug treatments or focused physiotherapy and exercise.
91: Prototype Development for Treatment of Periprosthetic Fractures of the Distal
Femur
Aaron M Muizelaar, ON; Mitchell Winemaker, ON; Cheryl E Quenneville, ON; Gregory R
Wohl, ON
Purpose: Current stabilization methods for periprosthetic fractures of the distal femur have
been inadequate in achieving sufficient fixation. Reported complications include nonunion
(9%), fixation failure (4%), infection (3%), and revision surgery (13%). The purpose of this
study was to develop and evaluate a new bilateral plating technique that would increase
stabilization, facilitate bony healing, and maintain overall alignment of the prosthesis with
respect to the femur.
Method: Medial and lateral stainless steel locking plates were designed based on the
geometry of the distal femoral condyles of a synthetic femur and a femoral prosthesis. To
take advantage of the rigidity of the prosthesis as well as to maintain alignment and
stabilization of the fracture, the distal end of each plate has a small tab that inserts into the
slot on either side of the prosthesis used during surgical implantation. A 3mm wide transverse
supracondylar fracture was created 5mm proximal to the anterior aspect of the prosthesis. A
single transcortical compression bolt along with several locking screws were used to secure
each plate to the femur and the prosthesis. The implanted femur was loaded in axial
compression (0º flexion) at incremental loads to 600N and in posterior bending (90º flexion)
incrementally to 500N. Medial and lateral unicompartmental loading was also performed in
the axial orientation to simulate varus and valgus loading. Testing was repeated five times in
each configuration to assess repeatability.
Results: Fracture motion, calculated at each load increment using a digital microscope, was
highly repeatable. Posterior loading at 500N caused shear (0.77±0.06mm in the transverse
plane), axial compression (0.20±0.02mm), and rotational (17.3±1.9°) motions. Axial loading at
600N resulted in corresponding values of 0.004±0.02mm, 0.07±0.01mm, and 1.4±0.4°.
Unicompartmental loading caused shear and compression displacements of 0.08mm and
0.06mm for valgus loading, and 0.05mm and 0.08mm for varus loading.
Conclusion: Optimal fracture healing has been shown to occur when gap motion is within 210% of the total gap size (0.06-0.30mm for a 3mm gap). All displacement values fell below
10% except for shear motion during posterior bending. However, at a more clinically relevant
rehabilitation load of 200N, an average shear of 9.7% was observed and distal rotation was
reduced. No other known studies use both medial and lateral plates, or incorporate the
femoral prosthesis into stabilization of the fracture. A previous study found that the fracture
site experienced shear and compression displacements of 6.4mm and 3.5mm with a single
lateral plate, and 1.1mm and 0.7mm when fixed with an intramedullary nail. These values
suggest that the proposed bilateral plates are capable of greatly improving the stability of the
fracture in comparison to current fixation techniques.
92: Rabbit Joint Capsule Cells Collagen Gel Contractile Properties: Parallels to Human
Post-traumatic Contractures
Kevin Hildebrand, AB; Mei Zhang, AB; Paul Salo, AB; A Dean Befus, AB; Dave Hart, AB
Purpose: The joint capsule is the critical anatomic structure limiting joint motion. Previous
work has suggested a myofibroblast-mast cell-neuropeptide axis of fibrosis in the pathologic
capsule. Using an in vitro collagen gel contraction assay, we test the hypothesis that rabbit
joint capsule cells (JC) can contract the gel, and that this is stimulated by mast cells (MC) and
enhanced further with Substance P (SP).
Method: Six rabbits had a standardized surgical procedure performed on the right knee to
produce post-traumatic joint contractures. The rabbits were killed 8 weeks after surgery and
the joint capsules were minced, placed into culture flasks and resulting cells incubated. Upon
confluence, cells were trypsinized, re-suspended at selected densities, and mixed with
neutralized collagen solution composed of 59% neutralized PureCol collagen. The human
mast cell line, HMC-1, and the NK1 receptor antagonist RP67580 (NK1 is the SP receptor)
were obtained. Aliquots (500 μl) of collagen gel with only JC (2.5 × 105), MC (7.5× 105), or
JC (2.5 × 105) and MC (7.5× 105) [1:3] were then casted into wells of a 24- well culture plate.
In some experiments, SP (1 x 10-6 M) +/- RP67580 (0.05 mM) were added. The gels were
maintained with DMEM/F-12 plus 1% serum replacement and incubated at 37°C. The gels
were detached from the wall and the bottom of culture plate wells, and photographed
between 0 - 72h post- release. The areas of gel were measured using an image analyzer.
Statistical analysis involved ANOVA with posthoc Tukey correction. P < 0.01 was significant.
Results: Joint capsule cells contracted the collagen gels and this was enhanced in the
presence of SP, although not statistically significant. Joint capsule cells combined with MC
enhanced the gel contraction more than JC alone or with SP (p<0.001). The addition of SP
accelerated the JC mediated gel contraction in the presence of MC the greatest (p<0.001
over all other conditions). The inhibitor RP67580 decreased the collagen gel contraction
induced by JC, even when MC and SP were present in optimal numbers / concentrations.
Finally, MC alone or with SP were unable to contract collagen gels.
Conclusion: Rabbit JC contract collagen gels. This contraction is enhanced in the presence
of human MC. It is further increased by SP and this response is specific since it is diminished
by the NK1 receptor antagonist RP67580. This interaction of JC, MC and SP is complex.
While not presented in this abstract, the effects are dose dependent. These findings validate
the experimental technique, although the concentrations in the joint capsule in vivo are
unknown. This in vitro research shows similar responses to MC and SP by JC from rabbit
and human post-traumatic contractures further validating the animal model with the human
condition. Given that previous in vivo research has shown the potential for a MC stabilizer
approved for human use to decrease joint contractures in the rabbit model, there is support
for the use of MC stabilizers in human trials.
93: The Correction of Medial Joint Loading with Valgus Unloader Brace is Related to
Varus Thrust
Janet Conrad, NS; Cheryl Hubley-Kozey, NS; Janie L Astephen-Wilson, NS; Michael J
Dunbar, NS; William Stanish, NS
Purpose: Total knee replacement surgery waitlists exceed recommended times and
projected demands will not be met by orthopaedic human resources; hence the need for
effective non-operative treatments of knee osteoarthritis (OA). Valgus unloader braces (VUB)
are a treatment option for medial compartment knee OA. Braces are purported to apply a
valgus load to the knee, reducing medial compartment loading associated with disease
progression. Studies are inconclusive on the mechanism by which VUB affect joint loading,
making prescription difficult. Varus thrust is an abrupt lateral motion of the knee in early
stance during weight acceptance (Chang et. al, 2010) present in a number of individuals with
knee OA. The aim of the present study was to determine the effect of VUB on medial
compartment loads and examine the changes in frontal plane angles as a mechanism for
change in loading.
Method: Thirty-three individuals with moderate, medial compartment knee osteoarthritis (OA)
(25 males, eight females, 57.6(8.7) years) were prescribed a VUB. 3D motion (OptoTrakTM)
and ground reaction forces (AMTI) were captured during walking with and without the brace.
Condition was randomly assigned. Frontal plane knee moments and angles (varus/valgus)
were calculated using inverse dynamics and Euler equations (Landry et. al, 2007). Principal
component analysis identified key amplitude and temporal changes of the frontal plane
moment waveforms during gait (Landry et. al, 2007). Participants were grouped based on
changes in frontal plane moment magnitude (a surrogate measure of medial compartment
load) with brace application: i) those that increased knee loads, ii) those who did not change,
and iii) those that decreased loads when the brace was applied. Varus thrust was identified
as the range in frontal plane angle within the first 30% of the gait cycle. Two-Way ANOVA
tested for differences among groups and the brace and no brace condition for the minimum
and maximum angles in early stance, and varus thrust. Alpha was set at .1 as this was a
preliminary study.
Results: Three equal sized sub-groups were identified based on the change in frontal plane
loading caused by brace wear. Significant condition (brace/no brace) differences were found
for the minimum angle and varus thrust (p<0.1 ). Varus thrust was larger and the minimum
angle was more valgus during brace condition. A significant group by condition interaction
(p<0.1) was found for the maximum angle. Post-hoc testing indicated that the increase group
had increased varus alignment at the end of varus thrust during the brace condition.
Conclusion: This preliminary study provides novel findings that the VUB does not provide a
consistent change to frontal plane mechanics of the knee. While the VUB placed the knee in
more valgus initially, different responses were found when the knee was loaded during
walking. These results have implications for who may or may not benefit from VUB
prescription.
94: Association of Vitamin D Receptor (VDR) Gene Polymorphism and Vitamin D Status
in Knee Osteoarthritis
Divya Sanghi, IN; Rajeshwar Nath Srivastava, IN
Purpose: Evidence suggests that low serum levels of vitamin D may increase the severity of
Osteoarthritis (OA). VDR gene polymorphism is known for its association with osteoporosis.
The inverse relationship between osteoporosis and OA suggests that VDR gene
polymorphism is a candidate gene to be associated with OA. This study was done to analyze
the association of vitamin D receptor gene polymorphism (Taq1 and Apa I) and serum vitamin
D levels in knee osteoarthritis
Method: This case control study consisted of 180 Osteoarthritis Knee patients and 150
controls. Cases were clinically diagnosed according to ACR criteria. Gradation of the disease
was done by using KL grading system on the basis of radiological findings. The serum levels
of vitamin D were assessed by using kit of Enzyme Linked Immunosorbent Assay. Detection
of VDR gene polymorphisms (Taq1 and Apa I) were done by PCR-RFLP technique
Results: We observed an insignificant association for genotypes of TaqI(p=0.086) and
ApaI(p=0.60) polymorphism between cases and controls.However, for TaqI marginal
significant association (p=0.053, OR 1.4, 95% CI 1.008-1.945) was observed between wild
type(T) allele and mutant type(t) allele, but for Apa I, there was no significant difference
(p=0.334, OR 1.17, CI 1.367-1.867) between wild type(A) allele and mutant type(a) allele.We
observed a significant association of low level of serum vitamin D levels in homozygous
mutant(tt) genotypes as compared to heterozygous(Tt) and wild type(TT) genotypes. But In
case of ApaI, we found higher serum vitamin D levels in homozygous mutant(aa) genotype in
comparison to heterozygous(Aa) and wild type(AA) genotype but this difference was not
statistically significant
Conclusion: Though insignificant association was found between osteoarthritis and the
genotypes of TaqI and ApaI polymorphism, a significant association with mutant allele of
TaqI(t) was observed. Additionally, the association of mutant allele with reduced level of
vitamin D was noted
95: Co-Culture of Meniscus Fibrochondrocytes and Bone Marrow Mesenchymal Stromal
Cells on a Collagen Scaffold for Inner Meniscus Reconstruction
Adetola B Adesid, AB; Stephanie T Lim, AB; Norah-Faye Matthies, AB; Aillette Mulet-Sierra,
AB; Nadr M Jomha, AB
Purpose: Meniscus is a fibrocartilaginous tissue crucial for healthy knee joint biomechanics.
The reparative capacity of the meniscus is limited to the outer vascularized region and injuries
in the inner avascular portion do not heal often leading to early development of osteoarthritis.
Cell-based tissue engineering has been advocated to formulate a living and transplantable
meniscus substitute. However, this strategy requires sufficient number of cells to produce
functionally competent extracellular matrix (ECM) proteins that are central to the biomechanical
role of the meniscus. We have demonstrated that combining human meniscus cells (MC) and
bone marrow mesenchymal stromals cells (BM-MSCs) in a biomaterial-free microenvironment
results in a synergistic increase in the production of ECM characteristic of inner meniscus. With
the goal to generate a cell-based meniscus substitute, we investigated the matrix-forming
capacity of co-cultures of MCs and BM-MSCs on a clinically approved collagen I-based
biomaterial. We hypothesized that a collagen I-based scaffold will support the formation of an
inner meniscus-like tissue after co-seeding with MCs and BM-MSCs.
Method: Menisci were harvested from 4 patients (mean age: 60.5) after total knee
arthroplasty. MCs were obtained after menisci digestion with collagenase and plated in DMEM
plus 10%FBS at 37°C under 21%O2 in a humidified incubator with 5%CO2. Bone marrow
aspirates were obtained from the iliac crest of 4 patients (mean age 55.5) undergoing routine
orthopaedic procedures. BM-MSCs were obtained by plastic adherence after cultivation of
bone marrow mono-nucleated cells. BM-MSCs were used at passage 2. MCs and BM-MSCs
were seeded simultaneously into collagen I scaffolds (DuraGen) and cultured in a serum-free
medium containing TGF-beta 3. MC:BM-MSC ratio was 25:75, and the total cell number was 1
x 10E6. Scaffolds containing pure MCs or pure BM-MSCs served as experimental controls. All
cell-scaffold constructs were cultured for 3 weeks under 21%O2 in a humidified incubator with
5%CO2. Constructs were analyzed for glycosaminoglycan (GAG) and DNA contents, and for
cartilaginous matrix gene and protein expression.
Results: Constructs from co-cultured cells demonstrated enhanced synthesis of DNA (1.53fold) and GAG-rich matrix (1.46-fold) and collagen II (2-fold) expression relative to controls.
Increased collagen II deposition was confirmed histologically. Collagen I expression was the
same in all constructs. There was some evidence of hypertrophic chondrogenesis of BM-MSCs
in all BM-MSCs laden constructs; although, to a lesser extent in constructs derived from cocultured cells.
Conclusion: Our data provides evidence that co-culture of MC and BM-MSCs on a collagen I
scaffold is a feasible strategy to generate a living implant for inner meniscus reconstruction.
Further investigation to mitigate hypertrophic differentiation of BM-MSCs is needed to establish
phenotypic stability of the co-cultured cells.
96: Differentiation of Mesenchymal Stem Cells by Soluble Factors Mediated by Direct
Co-Culture of Meniscus Cells and Mesenchymal Stem Cells
Mark F Sommerfeldt, AB; Leila Laouar, AB; Aillette Sierra, AB; Nadr Jomha, AB; Adetola
Adesida, AB
Purpose: Normal knee function is dependent upon healthy menisci. Injury to the menisci has
been shown to affect joint loading and lead to osteoarthritis. Cell-based strategies are being
pursued as an option in the treatment of meniscus injury. However, culture expanded
meniscus cells (MCs) lose the ability to express matrix proteins that are essential to meniscus
function. Previous work has shown that co-culture of mesenchymal stem cells (MSCs) and
unexpanded MCs enhances matrix production of MCs. Co-culture of MSCs with MCs,
chondrocytes (Ch) or nucleus pulposus (NP) cells has been shown to induce differentiation of
MSCs towards MCs, Ch and NP, respectively. In this experiment, MSCs and MCs were cocultured using direct and indirect cell to cell contact. We hypothesized that co-culture of MSCs
and MCs in direct contact would potentiate the expression of soluble factors that are capable
of inducing chondrogenic differentiation of MSCs.
Method: With ethics committee approval, bone marrow aspirates were obtained from iliac
crests of three donors undergoing orthopaedic procedures. MSCs were isolated and expanded
under 3% oxygen tension in α-MEM plus 10% FBS and basic fibroblast growth factor (5ng/mL)
until passage two. Menisci were obtained from three patients undergoing total knee
arthroplasty. MCs were isolated after menisci digestion with collagenase II (0.15% w/v) at 37˚C
for 22 hours in DMEM plus 5% FBS and plated in DMEM plus 10% FBS for 24-48 hours.
MSCs and MCs were co-cultured in two different configurations. In Group One, MSCs were
separated from pure MCs by a 0.4 micrometre porous membrane. Using a similar membrane,
Group Two MSCs were separated from a direct co-culture of MCs and MSCs (1:3 ratio). Two
control groups consisted of 1)MSCs separated from MSCs and 2)MCs separated from MCs.
After 10 days of culture, RNA was isolated and quantitative real-time PCR was used to assess
the gene expression profile of matrix genes: collagens I-III, aggrecan, biglycan, fibromodulin
and SOX-9 and a reference gene [human RNA polymerase II (RPII)]. Gene expression was
then normalized to RPII and compared.
Results: Group Two MSCs demonstrated a stastically significant up-regulation of aggrecan
gene expression compared to Group One MSCs (p<0.05). There was significant (p<0.05) upregulation of collagen IIB, IIA, and SOX-9 gene expression in Group One MCs (MCs separated
from MSCs) compared to the MC control group.
Conclusion: Co-culture of MSCs and MCs in direct contact may increase the expression of
soluble factors that are capable of inducing chondrogenic differentiation of MSCs. Secondarily,
co-culture of MCs and MSCs separated by a porous membrane may be a means of
maintaining MC phenotype as evidenced by increased expression of collagen producing genes
by MCs. Expression of soluble factors from each group of cells is the likely explanation by
which these interactions occur. Identification and use of these factors could enhance cellbased strategies aimed at meniscus repair and regeneration.
97: Increased Subchondral Bone Density Associated with Hip Impingement
Andrew D Speirs, ON; Paul E Beaulé, ON; Kawan Rakhra, ON; Hanspeter Frei, ON
Purpose: To examine acetabular subchondral bone density differences between subjects with
symptomatic and asymptomatic cam-type femoro-acetabular impingement deformities, and
normal asymptomatic controls.
Method: Patients undergoing surgery for correction of cam-type hip impingement deformities
were recruited (‘Surgical’ group) as well as asymptomatic volunteers; asymptomatic subjects
were classified has having a deformity (‘Asymptomatic’) or no deformity (‘Control’) based on
the alpha angle. Five subjects in each group underwent quantitative CT scans, including a
calibration phantom, of the pelvis from the iliac crest to lesser trochanter. Both acetabuli were
segmented for each patient. The surface model of each acetabulum was then divided into 12
wedge-shaped regions of bone, 10mm deep, and a tetrahedral mesh was generated for each
wedge. Image intensity was sampled in each tetrahedron using Amira (v5.3) software and
converted to bone mineral density (BMD) according to the phantom manufacturer’s guidelines.
The average BMD was calculated for each wedge as the volume-weighted density average of
all elements in each wedge. Differences between study groups were then analyzed using
ANOVA using BMD in the centre of lumbar vertebra L5 as a covariate to account for general
inter-patient BMD differences.
Results: In the superior i.e. load bearing region, average BMD ranged from 404 to 463 mg/cc
in the symptomatic hip of the surgical group; 435 to 481 mg/cc on side with deformity in the
asymptomatic group and 372 to 408 mg/cc in the control group. In the antero-superior region,
where impingement is most likely to occur, the surgical and asymptomatic groups had BMD of
460 mg/cc and 481 mg/cc, compared to 407 mg/cc in controls. The surgical and asymptomatic
groups had higher BMD in all superior regions compared to the controls in both hips (p<0.05).
Conclusion: Subjects with cam deformities showed higher acetabular subchondral BMD even
in asymptomatic hips. This sclerosis is likely a remodelling response to the stress
concentration caused by the deformity. Increased subchondral bone density results in
increased bone stiffness and may influence cartilage stresses. As many as 80% of patients
with cam deformities have bilateral deformities, although only 26% report bilateral symptoms.
Furthermore, this study found asymptomatic subjects with cam deformities had higher BMD
compared to controls, suggesting that subchondral sclerosis may play an important early role
in osteoarthritic degeneration. Understanding this role could help elucidate degenerative
pathways and help identify which deformities will lead to symptomatic degeneration.
98: Is Radiology a True Predictor of Clinical Severity in Knee Osteoarthritis?
Divya Sanghi, IN; Rajeshwar Nath Srivastava, IN
Purpose: Although discordance exists between clinical and radiographic profiles, it remains a
convention to diagnosis knee osteoarthritis (KOA) by ACR guidelines and its severity by KL
grades. This customary approach is in continuum because nothing better could be evolved.
This study was undertaken to resolve a much debated issue as to why clinical features do not
correlate significantly with radiological KOA.
Method: We postulated that there might be a particular reason for wide variation in the degree
to which clinical symptoms relate radiographic KOA and vice versa. The discordance noted by
many authors is primarily due to the limitations of outcome measures in their radiographic
study. We extended the radiological features beyond those included in KL Grades and
analyzed them with clinical symptoms. 180 cases of primary KOA were profiled for
demographic, clinical and radiological features. All the radiographs were evaluated for
individual radiological features (IRF) on index knees by an Orthopedic Radiologist. Clinical
scores were separately correlated with IRF to look for an association
Results: Pain & functional disability were significant with increasing KL Grades (p=0.03,
p=0.02) whereas stiffness was not. On analysis of individual radiological features, WOMACpain was significant with subchondral sclerosis (p=0.04), joint space width (p= 0.02) and tibiofemoral alignment (p=0.02). VAS-pain was significant with later two and articular incongruity
(p=0.00). Functional disability was associated with medial joint space narrowing (p=0.02),
tibiofemoral alignment (p=0.03), loose bodies (p=0.04) and juxtra articular osteopenia (p=0.01).
However in linear regression model pain and stiffness was significantly associated with
articular incongruity (p=0.00, p=0.01) and functional disability (p=0.04) and clinical severity
assessed by total WOMAC scores with juxta articular osteopenia (p=0.03).
Conclusion: Articular incongruity emerged a truer representative of pain and stiffness
whereas Juxta articular osteopenia strongly correlated with physical disability and clinical
severity in knee osteoarthritis. This study has essentially analyzed many more of the
radiological features than in many previous studies and this may have contributed to the
increased association between clinical and radiographic features
99: MR Imaging can Quantify Large Areas of Ablation Generated with a Novel Bipolar
Cooled Radiofrequency (BCRF) Probe in a Preclinical Bone Metastatic Model
Padina Pezeshki, ON; Margarete Akens, ON; Jason Woo, ON; Emily Won, ON; Cari M
Whyne, ON; Albert Yee, ON
Purpose: Radiofrequency ablation (RFA) is currently being used in the treatment of skeletal
metastases. RFA works by locally inducing ionic heating to ablate tissue, however it has been
limited by small ablative zones and incomplete tumour kill. A recent RF development utilizes a
cooling system together with bipolar circuitry to create a novel probe optimized for bone
treatment. This new bipolar cooled RF (BCRF) is designed to enable a larger zone of ablation
and a more effective heating pattern within the bone structure. The objective of this study was
to quantify performance of the BCRF probe in ablating large tumours within rabbit femora and
to determine an optimum MR imaging protocol for evaluating the region of effect of the novel
RFA probe.
Method: Twelve New Zealand White rabbits received a 200 µl injection of VX2 suspended
tumour cells into one femur. On day 14 post injection, MR images were acquired of 12 tumour
bearing femurs and 12 healthy contralateral limbs, following BCRF or a sham treatment (no RF
delivery). Post treatment MR imaging was repeated on day 28, followed by euthanasia and
dissection. MR imaging was performed on a 3.0T GE scanner using a 5" surface coil. Images
were acquired using standard 3D-SPGR and 3D-FIESTA sequences with a typical FOV of
16x16 cm (matrix = 256x256), slice thickness of 3mm, TR/TE 8.3/3.1 ms and flip angle of 55
for the FIESTA sequences and (matrix = 512x512), slice thickness of 3mm, TR/TE 4.4/1.6 ms
and flip angle of 30 for the SPGR sequences. Gd-DTPA contrast agent (0.1mmol/kg) was
injected in the rabbits and post contrast images were acquired. These images were used to
determine the tumor and ablation volume (Amira 5.2, Visage Imaging).
Results: The ablation volume was measured for each of healthy and tumour-bearing treated
femurs using both FIESTA and SPGR sequences, with and without contrast agent. The overall
average for ablation size was 5285±1514 mm3. It was observed that while all sequences were
comparable, gadolinium enhanced images of both sequences were best in determining the
region of effect of BCRF treatment with a high correlation of 99% (p=0.00) between the two
sequences in tumour treated regions and 94% (p=0.005) in healthy treated regions. The
untreated sham tumor samples demonstrated a rapid growth of tumor in the bone (i.e. volume
more than doubled). In general, detection of regions of interest using SPGR sequences was
found to be easier as it was possible to capture higher resolution SPGR images than the
FIESTA images in the same amount of time.
Conclusion: This study verified the large region of effect created by the BCRF probe. As such
this novel device may offer a solution for the common shortcoming of RFA devices that
generate small regions of ablation. Additionally it demonstrated the utility of contrast-enhanced
MR imaging when determining the ablation effect in clinical situations.
100: Intronic Single Nucleotide Polymorphism (SNP) of CALM-1 Gene is Significantly
Associated with Osteoarthritis Knee: A Case Control Study
Divya Sanghi, IN; Rajeshwar Nath Srivastava, IN; Sachin Avasthi, IN
Purpose: Though the pathology of osteoarthritis is well defined, the etiological factors are not
fully characterized. Genetic exploration of genome has resulted in several susceptibility loci
isolation confirming the genetic association of disease. The Japanese population has shown
higher incidence of osteoarthritis in patients having intronic and core promoter SNP in CALM-1
gene. At the same, Caucasian and Greek population showed absence of any such
predisposition in their population with the CALM-1 gene SNP.The objective of the study was to
determine the association of CALM1 gene polymorphism with knee osteoarthritis
Method: We planned a case control study in patients of primary osteoarthritis knee with aims
being to study the presence of CALM-1 gene SNP, correlation of its presence with
osteoarthritis and its correlation with clinico-radiological stage of the disease. 120 cases and
120 controls were enrolled. Clinicoradiological features were noted and symptomatic clinical
scoring was done. Genetic polymorphism in relation to intronic region of Calm-1 gene was
studied by DNA extraction, PCR and RFLP method. Statistical analysis was done using Stata
software
Results: 39 (32.50%) cases and 18 (15%) controls showed the presence of SNP which was
significant ( P value = 0.0022). Among SNP positive cases and controls, 5 (8.7%) cases and
none controls were heterozygosis for the occurrence of SNP. On regression of affecting
variables against SNP, taking the presence of osteoarthritis as dependent variable, we
calculated the adjusted odds ratio of all the significant variables. Thereafter, on logistic
regression to see the effect of variables on the occurrence of disease, we found age, sex, and
presence of SNP affecting the occurrence of disease significantly ( p value < .05).
Conclusion: CALM-1 gene intronic SNP (rs3213718) is present in Indian Population. The
target SNP is significantly affecting the disease as the difference between cases and controls
is highly significant (p value = .0022). Females are more predisposed for OA. Mean age of
presentation in cases was 53.31+/-9.5 years. Age is a significant factor in causation of disease.
However it is not influenced by existence of SNP. Between cases and controls, height, weight
and BMI did not show any significant difference
101: A Clinical Evaluation of a CT-based Patient Specific Femoral Alignment Guide for
Hip Resurfacing Arthroplasty
Michael Olsen, ON; Douglas Naudie, ON; Abigail Thompson, ON; Jane Morton, ON; Richard
McCalden, ON; Emil H Schemitsch, ON
Purpose: Alignment of the initial femoral guidewire is critical in avoiding technical errors that
may increase the risk of failure of the femoral component. A novel alternative to conventional
instrumentation for femoral guidewire insertion is a computed tomography (CT) based
alignment guide. The aim of this study was to assess the accuracy of coronal femoral
component alignment using a CT-based, patient specific femoral alignment guide.
Method: Between March 2010 and January 2011, 25 hip resurfacings utilizing a CT-based
femoral alignment guide were performed by three surgeons experienced in hip resurfacing.
Pre-operative radiographic templating was performed to assess the native femoral neck-shaft
angle (NSA) and the planned coronal stem-shaft angle (SSA). Pre-operative templating data
was used to plan individual femoral alignment guides. Minimum 6 week post-operative digital
radiographs were used to assess the stem-shaft angle of the implanted femoral components.
Results: Pre-operative templating determined a mean NSA of 134.5 degrees (SD 5.4, range
124-142 degrees). The planned SSA was a relative valgus alignment of 7.0 degrees (SD 5.7,
range -6-14 degrees). A segmentation error occurred in the manufacturing of one of the jigs
which did not fit the femoral head of the patient intra-operatively. Imageless computer
navigation was used instead to implant the initial guidewire and this patient was excluded from
further analysis. The post-operative SSA differed from the planned SSA by a mean of 1.3
degrees (SD 4.8, range -9-14 degrees). There was no significant difference between surgeons
in post-operative SSA accuracy (p=0.697). The final SSA measured within ±5 degrees of the
planned SSA in 20 of 24 cases (83%). There was one complication of a deep venous
thrombosis in the series.
Conclusion: CT-based, patient specific guidewire alignment jigs provided a satisfactory level
of accuracy for coronal alignment of the femoral component with no difference in accuracy
attained between users. Accuracy results of the device approach those previously established
for imageless computer navigation in hip resurfacing arthroplasty.
102: An analysis of the Hip Resurfacing failures - Canadian Experience
James N Powell, AB; Canadian Orthopaedic Arthroplasty Society (COAS), ON
Purpose: A series of 2773 hips demonstrated a KM five year overall survivorship of 96.3%. An
analysis of the revisions was undertaken to assess the factors associated with failure, and to
determine whether altered patient selection, surgical implant choice or surgical technique can
lead to improved outcomes.
Method: A series of 2773 (2452 patients) hip resurfacings from 11 Canadian centers during
the period January 2001 to December 31, 2008 were reviewed. Each center was required to
have performed 50 resurfacing cases for inclusion into the analysis. Data points collected
included patient demographics, diagnosis, prior operations, implant used, component size and
reason for revision, as well as intra-operative and post-operative complications. Radiographic
analysis was performed using DICOMeasure software ( View Tec, MXD Ltd. UK.)
Results: 94 failures were assessed. The major cause of revision was femoral neck fracture 25.
Other causes of failure included: femoral component loosening 17, acetabular loosening 14,
Infection 13, undiagnosed pain 10, AVN five, hip impingement four, four patients had a revision
for a pseudotumor. One patient had high metal ion levels necessitating revision and one
patient was revised for poor function.
Conclusion: The reasons for failure in our series are consistent with other published reports.
Femoral neck fracture is one of the major causes for resurfacings to fail. Proper patient
selection and surgical technique are important to prevent this. The rate of pseudotumors in our
series is less than reported in other studies. Hip resurfacing failures may be reduced by
resurfacing male paitents with a larger head diameter and by using resurfacing systems with a
higher survivorship.
103: Clinical Results of a Hybrid Metal-on-Metal Resurfacing Prosthesis: An
Independent Series.
Paul E Beaulé, ON; Alejandro Zylberberg, ON; Toru Nishiwaki, ON; Paul R Kim, ON
Purpose: As we enter the second decade of hip resurfacing for the treatment of hip arthritis,
data from independent centers becomes critical to assess its overall efficiency and safety. The
purpose of this study is to present the short to mid-term results of a single center’s experience
with a metal-on-metal hip resurfacing device.
Method: From 2001 to 2009, 548 hip resurfacings were performed using the Conserve Plus
prosthesis in 460 patients (351 males) with a mean age of 48.3 years (18 to 66). Degenerative
osteoarthritis was diagnosis in 505 hips. At the 6 week follow-up, stem and cup alignment was
assessed using standard radiographs.
Results: Mean follow-up was of 4.2 years (range, 2 to 8.1). No patients were lost to follow-up.
Twenty-one (3.9%) patients required conversion to THR: acetabular loosening (9), neck
fracture (4), unexplained pain (3), femoral loosening (2), adverse tissue reaction (2) and 1
infection. 5 patients had isolated acetabular component revision and maintained as a
resurfacing. At the minimum two-year follow-up, the presence of a vertical cup at 6-weeks was
associated with radiolucencies at final follow-up (χ2=17.00, p<.001). Five-year implant survival
was 95% (95% CI: 93% to 96%).
Conclusion: We continue to use the prosthesis in young active patients with good bone mass.
However, acetabular component fixation remains a concern and may be related to the cobalt
chrome interface.
104: Does Etiology Affect the Course of Femoral Head Osteonecrosis?
Mansour Abolghasemian, IR; Mehdi Ramezan Ramezan Shirazi, IR; Oleg Safir, ON;
Mohammad Ghazavi, IR
Purpose: Osteonecrosis of the femoral head (ONFH) is one of the leading causes of hip
degeneration in the young in Iran. Although it may happen without any obvious causes, some
etiologic factors have been linked to the disease. The natural history of the disease is still
unclear and the time to collapse of the femoral head varies in different cases. The impact of
each associated risk factor on the natural course of the disease has not been clearly
determined in the literature. However, recently, a steroid-containing opioid drug called
Temgesic has been being widely abused by drug addicts in Iran, resulting in increased
incidence of ONFH. The purpose of this study was to assess the effect of different etiologies,
including this new drug, on the course of ONFH. Since any joint preserving treatment should
ideally be performed before collapse happens, it is important to estimate the interval between
pain onset and head collapse in cases of ONFH.
Method: We retrospectively assessed all patients presenting with untreated ONFH due to one
of the following four etiologies; Steroid-induced (St), Temgesic-induced (Te), trauma-induced
(Tr) and Idiopathic (Id). Cases showing multiple risk factors were excluded. Only those cases
with sequential X-rays in whom the time of radiographic collapse was clear with maximal three
months accuracy were included. These four groups were compared regarding the average
time interval from pain onset to femoral head collapse, using ANOVA test.
Results: Of 149 patients with ONFH, 93 (150 hips) were eligible for the study. The average
age of the patients was 33.9 years and 82 patients were male. The etiology was found to be
steroid use in 70, Temgesic abuse in 43, trauma in 15 and idiopathic in 22 hips. Rate of
bilateral involvement was 70, 79, 0 and 64% for St, Te, Tr and Id groups, respectively.The
average time to radiologic collapse and osteoarthritis was 11.2 (±6.8) months for St group, 9.1
(±4.6) for Te group, 18.8 (±7.3) for Tr group and 21.9 (±14) for Id group, respectively.
Statistical analysis showed that there was no significant difference between St and Te groups,
or between Tr and Id groups (P value>0.7), but time to collapse was significantly shorter for St
and Te groups comparing to Tr and Id groups (P value<0.02).
Conclusion: Previous studies have failed to indicate a marked difference among etiologic
groups in collapse rate and some evidence exists indicating that without treatment, probably all
symptomatic ONFH cases ultimately collapse, but the average time of the collapse after pain
onset has not been known yet. The present study was performed retrospectively on
symptomatic cases that had already collapsed to assess this unknown parameter for different
etiologies. The temporal course of ONFH in Temgesic-induced cases was very close to those
due to steroids, showing that the main cause of ONFH for them is probably the steroid
ingredient. Importantly, it also showed that when symptomatic, a steroid-induced ONFH
probably runs a much faster course to collapse than trauma-induced or idiopathic ONFH.
Therefore, to be effective, any joint preserving treatment should be performed very early after
pain onset in hip osteonecrosis due to steroid use.
105: Assessment of Post-Impaction Acetabular Bone Gaps in Hip Resurfacing
Arthroplasty
Michael Olsen, ON; Bruno Gomes, ON; Michael Donnelly, ON; Ashesh Kumar, ON; Zachary
A Morison, ON; Emil H Schemitsch, ON
Purpose: Press-fit acetabular component seating in hip resurfacing can be challenging as a
strong interference fit is desired. Currently, a 2 mm under-ream of the acetabulum is
recommended to ensure adequate fixation. There are reports in the literature that suggest a
high prevalence of incomplete component seating utilizing press-fit acetabular components. It
has not been established whether a reduction in the under-ream of the acetabulum results in
reduced incomplete component seating and whether this leads to increased acetabular
loosening due to the reduction in theoretical interference fit. The aim of this investigation was
to assess the prevalence and natural history of post-operative interference gaps in hip
resurfacing and determine whether reduction of the acetabular under-ream from 2 mm to 1 mm
reduces the incidence of peri-acetabular radiolucencies.
Method: Between February 2005 and April 2010, 327 consecutive hip resurfacings were
performed by a single surgeon. Three observers assessed the frequency of peri-acetabular
interference gap radiolucencies using anteroposterior radiographs in 306 hips with a minimum
1 year radiographic follow-up. An interference gap was defined as a >50% longitudinal gap in
at least one of three zones of the acetabulum. Identified gaps were monitored for gap healing
at latest follow-up. The standard technique of preparing the acetabulum with a 2 mm underream was modified to a 1 mm under-ream in May 2008 and a comparison was made between
the proportion of gaps identified between the two methods of acetabulum preparation.
Results: Half of the post-operative radiographs (51%) demonstrated the presence of a periacetabular radiolucency. The maximal gap occurred in zone 2 in 151 cases (97%) and zone 1
the remaining four cases (3%). There were no gaps greater than 4 mm detected and 76%
(118/155) of gaps were ≤1 mm. At a mean follow-up of 2.7 years (range 1-6), 96% (149/155) of
radiolucent gaps had healed. Four of the six gaps demonstrating incomplete healing had less
than 2 years follow-up. The generalized kappa statistic indicated substantial agreement
between observers for gap presence and healing, κ=0.65 and κ=0.62, respectively. There was
a significant reduction in the number of interference gaps identified between acetabula
prepared with a 2 mm under-ream (92/145, 63%) and those with a 1 mm under-ream (63/161,
39%, p<0.001). There were 7 revisions in the series; there were no revisions due to acetabular
failure.
Conclusion: Peri-acetabular radiolucent gaps were common in this series; however, they
were not associated with acetabular component failure and have demonstrated a very high
rate of healing. Reducing the under-ream for acetabular preparation from 2 mm to 1 mm did
not result in any adverse sequelae and significantly reduced the incidence of peri-acetabular
lucencies. Aggressive acetabular component seating is unnecessary and the use of a 1 mm
under-ream is sufficient for adequate press-fit fixation of the acetabular cup in hip resurfacing.
106: Early Failure Rate Of Hip Resurfacing Arthroplasty With The ASR Implant
Stephen M Mann, ON; John F Rudan, ON; Graham Fedorak, ON
Purpose: To retrospectively review the failure rate of a consecutive series of ASR hip
resurfacing arthroplasties carried out at one institution over six years.
Method: One hundred thirty implants in 117 patients were reviewed radiographically, and
acetabular inclination was recorded from the first post-operative image and at subsequent
follow-up visits. Age, sex, femoral head component size, acetabular component generation,
the use of computer navigation, and cobalt and chromium ion levels were obtained from the
digital chart.
Results: Twenty-one patients (16%) had ion levels above threshold values, and five of 130
implants (3.8%) required revision for loosening. Aseptic failure was associated with increased
ion levels, but there was no statistically significant relationship with any of the other recorded
variables.
Conclusion: Increased blood levels of cobalt and chromium are common following metal-onmetal hip resurfacing arthroplasty, but do not reliably predict which patients will require
revision. The other variables examined in this study do not correlate with rates of aseptic
failure, which were similar to previously published values. Further research is necessary to
elucidate the relationship between metal ion levels and aseptic failure, and the clinical
significance of increased cobalt and chromium.
107: Long-term Graft Survival and Functional Outcome Following Free Vascularized
Fibular Transfer for Pre-collapse Osteonecrosis of the Femoral Head
William Eward, ON; Marc Richard, NC; Craig Rineer, NC; James Urbaniak, NC; David Ruch,
NC
Purpose: Osteonecrosis of the femoral head (ONFH) is a potentially debilitating condition
affecting primarily young patients. Disability and dysfunction progress following femoral head
collapse and degenerative hip arthrosis. Free vascularized fibular grafting (FVFG) has proven
a durable means of biological femoral head preservation. When employed in the precollapse
stages of ONFH, this treatment has great potential to alter the course of disease yet the long
term natural history and functional outcomes in this subset of patients is not well described.
Method: 61 patients (65 hips) who underwent free vascularized fibular grafting for precollapse
(Ficat Stages 1-3) ONFH were retrospectively reviewed. Mean follow up time was 14.4 years
(range 10.5-26.1 years). Graft survivorship, SF-12 MCS, SF-12 PCS, and Harris Hip Score
were calculated. Data about activity level and narcotic pain medication usage were collected.
Logistic regression of demographic and etiologic features was performed.
Results: 26 of 65 hips (40%) were converted to THA at a mean 8.3 years postoperatively,
leaving 39 of 65 hips (60%) with surviving FVFG at final follow up. Patients with idiopathic
ONFH were more likely to elect conversion to THA, especially at time points greater than 10
years postoperatively. 64% of patients with surviving FVFG participated in active events or
impact sports, compared with 38.4% of patients converted to THA. Although final Harris Hip
and SF-12 PCS scores were similar between groups, SF-12 MCS scores were significantly
higher (53.9 vs 49.7) in patients with surviving FVFG. 19.2% of patients who converted to THA
and 7.6% of patients with surviving FVFG were using narcotic pain medication at final follow
up. Demographic factors, additional procedures, and low preoperative function were not
associated with changes in graft survivorship.
Conclusion: Patients with precollapse, predegenerative ONFH who undergo FVFG have a
durable preservation of the femoral head which either prevents or significantly delays the need
for endoprosthetic hip reconstruction. In patients with successful long-term femoral head
preservation, Harris Hip Scores are equivalent to patients converted to THA while activity
levels and mental health scores are higher.
108: Lower-extremity Gait Mechanics of FAI Patients Do Not Return to Normal Following
Corrective Surgery
Mario Lamontagne, ON; Nicholas Brisson, ON; Matthew J Kennedy, ON; Paul E Beaulé, ON
Purpose: The purpose of this study was to determine the effects of cam FAI corrective surgery
on the biomechanics of the affected hip during level gait by comparing the hip threedimensional angular displacements, moments and powers of preoperative and postoperative
FAI groups with those of a healthy control group.
Method: Ten patients with unilateral symptomatic cam FAI, who underwent corrective surgery
using an open or combined technique, were compared preoperatively and postoperatively, and
with thirteen control subjects matched for age, sex and body mass index. Postoperative testing
occurred between eight and 32 months after surgery. Three-dimensional kinematics were
collected at 200 Hz using a nine-camera high-speed motion analysis system with 45 retroreflective markers affixed onto various anatomical landmarks, according to a modified Helen
Hayes marker-set. Ground reaction forces were recorded at 1,000 Hz during the stance phase
of the gait cycle using a force platform.Participants performed five successful barefoot walking
trials at a natural, self-selected pace, where the foot of the affected leg landed on the force
platform. The extracted variables of interest were the peak angles and ROM of the hip in all
three planes of motion during the gait cycle, as well as the peak hip moments in all three
planes of motion and the peak hip powers during the stance phase of the gait cycle.
Multivariate analyses of variance were performed to detect significant differences between the
groups. Using Bonferroni corrections, the alpha values used to determine statistical
significance were adjusted to α = 0.017 and α = 0.025 for all kinematic and kinetic variables,
respectively.
Results: Results demonstrated that both preoperative (p = 0.016) and postoperative (p =
0.016) FAI groups had reduced hip frontal plane ROM compared to the control group. The
postoperative FAI group also displayed reduced hip sagittal plane ROM compared to the
control group (p = 0.013). Likewise, the postoperative FAI group produced smaller peak hip
abduction (p = 0.013) and external rotation (p < 0.001) moments, and generated less peak hip
power (p = 0.004) compared to the control group.
Conclusion: The present study demonstrated that the affected hip biomechanics of cam FAI
patients during level walking do not return to normal following surgery. Preoperative hip
impairments, perhaps due to adopted modified gait patterns to reduce hip muscle contractions,
loading and pain, resulting in muscular disuse and atrophy, persisted postoperatively.
Additional impairments observed postoperatively may have resulted from the lack of complete
restoration of hip muscle function following surgical incision. FAI seems to be associated with
aberrant hip joint functions that have not yet been well identified. Further research, particularly
with use of electromyography, is required to confirm the reasons for which the hip
biomechanics of FAI patients during gait do not return to normal following surgery.
109: Outcomes of Joint Preservation Surgery: Comparison of Patients with Dynamic
Dysplasia of the Hip (DDH) and Femoroacetabular Impingement (FAI)
Paul E Beaulé, ON; Gillian Parker, ON; Kyle A Kemp, ON
Purpose: Both hip dysplasia (DDH) and FAI are recognized as a cause of hip pain and arthritis
in the young patient. Having said that, dysplasia is usually corrected with an extra-articular
corrective peri-acetabular osteotomy (PAO) whereas FAI requires intra-articular bony
correction. The purpose of this study was to compare the clinical outcomes of these two joint
preserving surgeries to determine if their clinical outcome is comparable.
Method: Thirty-six patients with DDH and 96 FAI were matched via a propensity analysis,
based on age, gender, and BMI giving 26 patients (10 males, 16 females); mean age and BMI
were 33.1(15-53), and 24.8 (17.3-40.0), respectively. At the time of surgery, mean Tonnis
grades were 0.4 (range: 0-2) for DDH versus 1.0±0.8 (0-2) for the FAI (p=0.03). Clinical
Outcome scores used were the WOMAC, SF-12, modified Harris Hip Score (HHS), UCLA
Activity Score.
Results: At baseline, there were no differences in outcome scores. At mean follow-up of
31mos (11-64), compared with FAI patients, those in the DDH group reported better WOMAC
stiffness (27.8±22.1 vs. 43.4±19.8, p=0.03), and SF-12 physical component (48.7±9.5 vs.
42.0±9.3, p=0.04) scores. In the DDH group, no significant correlations were observed
between Tonnis scores and outcome scores. In the FAI group, a moderate correlation (r=0.50)
was observed between Tonnis Score and baseline HHS.
Conclusion: In this propensity analysis, patients with FAI presented with a more advanced
disease than the DDH. As a whole, patients with DDH did better clinically than the FAI patients
which could be due the less advanced disease at the time of surgery or the fact that the
surgery in DDH is extra-articular.
110: Radiographic Evidence of Pincer-Type Femoroacetabular Impingement in Patients
with End Stage Hip Osteoarthritis
Paul RT Kuzyk, ON; Michael Edward Sellan, ON; Zachary A Morison, ON; James P Waddell,
ON; Emil H Schemitsch, ON
Purpose: In pincer-type femoroacetabular impingement (FAI), the acetabular labrum is more
susceptible to degenerative wear as a result of an exaggerated acetabular rim often presenting
in patients with acetabular retroversion or general overcoverage of the femoral head.
Radiographic measurements and markers suggestive of pincer-type impingement include the
lateral centre-edge angle (LCEA) of Wiberg, tonnis angle, posterior wall sign (PWS), crossover
sign (COS) and the prominence of the ishial spine (PRISS). Our study aims to determine if
patients with end-stage hip osteoarthritis (OA) have a higher incidence of radiographic markers
of pincer-type FAI as compared to control patients.
Method: The anteroposterior (AP) pelvis and lateral hip radiographs of 244 patients (261 hips)
who presented to our institution for hip arthroplasty or hip fracture fixation between 2006 and
2008 were retrospectively reviewed. Six cohorts were compared: Male (n=51) and female
(n=25) patients with end stage hip OA < 55 years old; Male (n=34) and female (n=50) patients
with hip OA ≥ 55 years old; Male (n=34) and female (n=65) hip fracture patients ≥ 65 years old
without radiographic evidence of hip arthritis used as controls. PWS, COS, PRISS, LCEA and
Tonnis angles were measured by three coauthors on AP pelvis radiographs for each cohort. A
one-way ANOVA with Tukey’s test was used to compare the LCEA and Tonnis angles for the
six cohorts. A Pearson chi-square test was used to compare the incidence of PWS, COS and
PRISS in the six study groups.
Results: Older female hip arthroplasty patients had significantly more patients with LCEA
values > 39°, indicative of pincer-type FAI, than any of the other 5 cohorts (36%; p<0.05).
Conversely, 32% of younger female arthroplasty patients displayed evidence of hip dysplasia,
defined as an LCEA < 20°, a trend which was not observed in patients from the other cohorts
(p<0.05). The younger female arthroplasty cohort also had the largest proportion of patients
with Tonnis angles > 10°, consistent with instability of the hip (p<0.001). Young males with
end-stage hip OA had significantly more patients with PRISS than any of the other 5 cohorts
(p<0.01). This trend was maintained for both affected and contralateral hips. The frequency of
acetabular retroversion, as noted by the presence of PWS, COS and PRISS, was highest in
male patients, independent of age or diagnosis (p<0.001).
Conclusion: Acetabular overcoverage contributing to pincer-type FAI was most pronounced in
older female arthroplasty patients. Hip dysplasia and instability was most evident in younger
females with end-stage hip OA. Younger male patients presenting for hip arthroplasty
displayed the highest frequency of markers of acetabular retroversion. Our study demonstrates
that patients with end-stage hip OA commonly display evidence of pincer-type FAI.
111: Clinical, Radiographic and Metal Ion Comparison of 36mm, 40mm and 44mm Metalon-Metal Total Hip Arthroplasty
Nayla G Papadopoulos, QC; Gregory Manoudis, QC; Sarantis Abatzoglou, QC; Laura Epure,
QC; Olga Huk, QC; David Zukor, QC; John Antoniou, QC
Purpose: Cobalt-Chromium alloy for metal-on-metal (MM) hip prostheses have superior wear
resistance compared to the conventional polyethylene-on-metal prostheses, making it a more
suitable alternative for younger patients. The potential carcinogenic effect of metal ions, mainly
Cobalt (Co) and Chromium (Cr), found in the blood of patients with MM hip prostheses is a
serious cause of concern. Tissue damage can be induced by oxidative stress. Total antioxidant status (TAS), total peroxides (TP), and nitrotyrosine (NT) are all oxidative stress
markers (OSM) thought to be affected by Cr and Co levels. As larger head bearings encourage
fluid film lubrication and consequently decrease wear, we hypothesize that metal ion levels as
well as oxidative stress markers may correlate with greater wear rates, smaller head bearings
and increased physical activity.
Method: We followed 90 patients undergoing total hip arthroplasty (THA) with different head
sizes of Cobalt-Chromium-Molybdenum (Mo) prostheses (34 patients for 36mm group, 42
patients for the 40mm group and 14 patients for the 44mm group). Patients’ follow-up occurred
at year 0.16, 0.33, 1 and 2. Patients with bilateral hip involvement, concurrent metal hardware,
multiple co-morbidities, inflammatory joint disease or infection were excluded from this study.
Whole blood samples collected at each follow-up visits were analysed by inductively coupled
plasma-mass spectrometry (ICP-MS) to determine the levels of Co, Cr and Mo. Serum
nitrotyrosine levels were quantified using Nitrotyrosine-EIA essay whereas total peroxide
concentration were measured with Biomedica OxyStat assay and TAS with the Oxford
Biomedical total anti-oxidant power kit. Radiographic analysis was performed using Einzel-BildRoentgen-Analyse (EBRA) cup software. During each visit, patients’ clinical outcomes were
recorded with calculation of Harris Hip Scores (HHS) and University of California Los Angeles
Activity Scores (UCLA).
Results: Using Mann-Whitney U test, preliminary results failed to show statistical difference in
metal ions concentration between each of our study group at any given follow-up time. For the
HHS correlation, we found a Spearman’s Rho of 0.20 (P=0.0009) for Co, 0.19 (P=0.0018) for
Cr and – 0.08 (P=0.2293) for Mo. For the UCLA correlation, a Spearman’s Rho of 0.27
(P=0.0001) was found for Co, 0.23 (P=<0.001) for Cr and -0.06 (P=0.3637) for Mo. Plasma
markers for oxidative stress also show no statistical correlation with metal ion concentration.
For the 36mm, 40mm and 44mm groups, the mean cup inclination angle was of 41°, 43° and
40° respectively.
Conclusion: Our results show no correlation between prosthetic head size and concentration
of metal ions released in the blood as well as between oxidative stress markers and metal ion
levels. No strong correlation was shown to be present between the metal ions concentration
and either the Harris Hip Scores or UCLA Activity Scores.
112: Delta Ceramic on Ceramic THA- Midterm Results including Squeaking and Liner
Fracture Rates
James P McAuley, ON; William Hamilton, US; Jeff Murphy, US; Thomas Blumenfeld, US;
Douglas Dennis, US
Purpose: Ceramic on ceramic (COC) is an attractive option for total hip replacement, but little
data exists on the alumina matrix composite at midterm follow-up. This study reports the
midterm results of an IDE study utilizing Biolox Delta COC.
Method: Three hundred and forty five patients received a Delta COC THA from 2003-2007 as
part of a prospective multicenter IDE study with head sizes of either 28mm (n=177) or 36mm
(n=168). Average patient age was 56.9 years and average BMI was 29.5. All patients were
followed yearly with clinical and radiographic evaluations.
Results: The survivorship estimate was 97.7% at 6.3 years with 95% confidence intervals (CI)
of 95.1% to 98.9%. Survivorship estimates by head size were 97.7% (95% CI 93.9% to 99.1%)
at 6.3 years for 28mm head sizes and 97.5% (95% CI 92.0% to 99.2%) at 4.2 years for 36mm.
There were 15 (4.3%) individuals who reported squeaking, 6 (3.4%) in the 28mm group and 9
(5.4%) in the 36mm group. Only 2 (0.58%) were reproducible in the clinic and none were
revised for squeaking. There were 3 (0.85%) postoperative liner fractures (2 in 28 mm (1.1%),
1 in 36 mm (0.6%)) and no ball head fractures.
Conclusion: The COC articulation has excellent 6 year survivorship of 98%. Although rare,
squeaking and liner fractures remain the weaknesses of this bearing articulation.
113: Early High Failure Rate of Large Head Metal-on-Metal Total Hip Replacement Using
a Mono Block Acetabular Component
Vikram Chatrath, ON; Paul E Beaulé, ON; Robert Feibel, ON; Peter Thurston, ON; Isabelle
Catelas, ON; Paul R Kim, ON
Purpose: The purpose of this study is to present the early clinical results of our center’s
experience with the use of large head MOM total hip replacement with a mono block
acetabular component.
Method: From October 2005 to May 2010, 89 procedures were performed in 88 patients (53
males, 35 females) by four surgeons usi
Femoral Head) which uses a large diameter femoral head (36-54 mm). The mean age of
patients was 59.7±9.8 years (20 to 79). Mean BMI was 29.5±6.2 (21.2 to 44.8). Post-operative
clinical follow-up consisted of a physical examination, standard radiographs, and three patientreported outcomes: WOMAC, modified Harris Hip Score (HHS), UCLA Physical Activity Scale.
Results: At mean follow-up (28 months, range: 14-65), all outcome scores showed
improvement (p<0.001). Scores were 13.7 vs. 51.0 pre-surgical (WOMAC Pain), 22.1 vs. 56.0
(WOMAC Stiffness), 14.8 vs. 53.4 (WOMAC Function), 15.1 vs. 53.1 (WOMAC Total), 83.2 vs.
53.7 (modified HHS), and 6.7 vs. 4.8 (UCLA Activity). However, eight cases required revision
at a mean of 29.9 months (range: 11 to 45). Reasons for revision: aseptic cup loosening (n=4),
pseudotumor (n=2), hypersensitivity to metal (n=1), and infection (n=1). At <3 years, our failure
rate for aseptic failure is 8.9%.
Conclusion: The current study reports a high failure rate of a large head MOM total hip
replacement due to poor acetabular component fixation as well as adverse tissue reaction.
Use of this implant should be restricted to conversion of a failed resurfacing arthroplasty.
114: Metal on Metal versus Polyethylene in Total Hip Arthroplasty: Ten-Year Results of a
Randomized Clinical Trial
Joseph B Assini, ON; Steven JM MacDonald, ON; Richard W McCalden, ON; Robert B
Bourne, ON
Purpose: To present the long-term results of a randomized clinical trial examining metal ion
levels in metal on metal (MoM) versus metal on polyethylene (MoP) bearing surfaces in total
hip arthroplasty.
Method: Forty-one (24 male, 17 female) patients undergoing total hip arthroplasty were
randomized to receive either a metal (23 patients) or polyethylene (18 patients) acetabular
insert. Patients were followed prospectively for a minimum of 10 years (mean 11.2 years,
range 10.1-11.9 years). Clinical, radiographic and metal ion analyses were done
preoperatively, and at 2, 5, 7 and 10 years postoperatively. Clinical outcome measures
included the Harris Hip score (HHS), Western Ontario MacMaster University Score (WOMAC)
and Short-Form 12 (SF12). Metal ion analysis evaluated the erythrocyte ion levels of cobalt,
chromium and titanium and the urine concentration of cobalt and chromium ions.
Results: Clinical outcome measures demonstrated no differences between metal on
polyethylene and metal on metal groups at 10 year follow-up. There were no radiographic
differences between groups. Patients in the MoM group were found to have a 5-fold increase
in erythrocyte cobalt levels at 10 years post-operative. Additionally, the urine cobalt and
chromium levels demonstrated 13.9-fold and 11.8-fold increases respectively. In the MoP
group only the erythrocyte chromium levels increased significantly over the 10 years of followup, demonstrating a 2.4-fold increase. Comparison of the MoM versus MoP groups showed a
significant difference in the median erythrocyte cobalt (0.7 ug/L vs. 0.1 ug/L, p<0.01), urine
cobalt (5.86 vs. 0.38, p<0.01) and urine chromium (3.05 vs. 0.23, p<0.01) levels. There were
no failures, revisions or patients diagnosed with metal hypersensitivity.
Conclusion: Compared to metal on polyethylene, metal on metal articulations were found to
produce increased erythrocyte cobalt and urine cobalt and chromium levels at 10 years postoperatively. The elevated metal ion levels that were seen early in followup in this series have
not decreased or diminished over time. To date, there have been no identified complications
associated with the metal on metal bearing cohort.
115: One Intraoperative Dose of Tranexamic Acid is Safe and Effective in Revision Total
Hip Arthroplasty
Kevin Smit, ON; Douglas Naudie, ON; James L Howard, ON
Purpose: Revision total hip arthroplasty (THA) has been associated with an increased risk of
perioperative blood loss requiring transfusions. Tranexamic Acid (TXA) has been proven to be
safe and effective in preventing blood loss in primary THA. Our purpose was to study the effect
of TXA on blood loss and transfusion rates in revision THA.
Method: We performed a retrospective comparative study on 343 patients who had undergone
revision THA between January 2006 and March 2010. 108 patients did not receive TXA while
235 patients received one intraoperative dose of 20 mg/kg of TXA given immediately before
skin incision. We then compared change in hemoglobin, transfusion rates, hospital length of
stay, and complications between the two groups. No other routine patient care practices or
blood conservation program strategies were altered during this time.
Results: There was a significant reduction in hemoglogin (Hb) loss in the TXA group
compared to the No TXA group for revision THA (48 ± 18 g/L and 43 ± 18 g/L, respectively,
p=0.01) and a significant reduction in transfusion rates (45.4% and 33.6%, respectively,
p=0.03) and average amount transfused (1.3 ± 1.9 units and 0.9 ± 1.6 units, respectively,
p=0.03). The effect of TXA on Hb loss was most significant in procedures that involved revision
of both the femoral and acetabular components (58 ± 18g/L and 49 ± 15g/L, respectively,
p=0.01). There was not a significant difference in recorded major adverse events with the
administration of TXA (nine and nine respectively).
Conclusion: One 20 mg/kg intraoperative dose of TXA significantly reduced red blood cells
loss and transfusion rates in patients undergoing revision THA compared to a patient cohort
whom did not receive the TXA protocol. This single dose protocol was not associated in an
increased complication rate.
116: Outcome Comparison of Revised Hip Resurfacing with Primary and Revised Total
Hip Arthroplasties
William Desloges, ON; Toru Nishiwaki, ON; Paul R Kim, ON; Kyle Kemp, ON; Paul E Beaulé,
ON
Purpose: A clinical advantage of hip resurfacing (HR) is the preservation of femoral bone,
facilitating revision surgery when indicated. To determine if patients: 1) undergoing HR revision
have comparable outcomes to patients undergoing primary THA or revision of primary THA; 2)
undergoing revision of both the femoral and acetabular HR components have different
outcomes than those undergoing isolated femoral component revision.
Method: Twenty-two HR patients who underwent HR revision to a THA were retrospectively
reviewed and compared to 23 matched (age, gender, BMI) patients undergoing primary THA
and 12 patients undergoing revision of primary THA. Patients completed the WOMAC and SF12 questionnaires prior to surgery and at latest follow-up. Blood loss, days in hospital,
complications, and outcome scores were compared between groups.
Results: The HR revision group had greater intraoperative blood loss compared to the primary
THA group (p= 0.002), but not the THA revision group. At follow-up, no differences in SF-12
scores were present, but higher WOMAC stiffness (p=0.014), function (p=0.016) and total
(p=0.033) scores were observed in the HR revision group, compared to primary THA. HR
patients undergoing revision of both components compared to femoral side only had
comparable SF-12, WOMAC stiffness, function, and total scores but overall higher WOMAC
pain scores (p=0.050).
Conclusion: Our results indicate the outcomes of HR revision are comparable to THA
revision, but not primary THA. Longer follow-up is required to determine if these differences
persist. Finally, HR patients undergoing revision of one or both components can expect similar
outcomes.
117: Porous Metal Revision Shells for Management of Contained Acetabular Bone
Defects at 5 to 10 Years Follow-up
Paul RT Kuzyk, ON; Amir Sternheim, ON; David Backstein, ON; George Goshua, ON; Yaron
Berkovich, ON; Oleg Safir, ON; Allan Gross, ON
Purpose: Porous metal acetabular revision shells were used to treat contained bone loss.
Method: Outcomes of 53 patients with less than 50% acetabular bleeding host bone contact
were compared to a control group of 49 patients with 50%-85% bleeding host bone contact. All
patients were treated with the same type of porous metal shell. Minimum follow-up in both
groups was 5 years (mean 72.4 months). Clinical, radiographic and functional outcomes were
assessed.
Results: There were 4 (7.5%) mechanical failures in the less than 50% host bone contact
group and no failures in the more than 50% host bone contact group (p-value 0.068). There
were 4 infections (3.9%) and 5 recurrent dislocations (4.9%) with a stable cup construct that
were revised to a constrained liner in both groups combined.
Conclusion: Given the complexity of the reconstructive challenge, porous metal revision
acetabular shells show highly acceptable failure rates at 5 to 10 years follow-up in the setting
of significant contained bone defects. This favorable outcome may be due to the improved
initial stability achieved by a high friction coefficient and the high porosity with better bone
ingrowth.
118: Reconstruction of Acetabular Bone Deficiency in Revision Total Hip Arthroplasty
with Shelf Grafts in Hip Dysplasia A Long –Term Survivorship Comparison between
Cemented and Uncemented Cups
Paul RT Kuzyk, ON; Amir Sternheim, ON; Yaron Berkovich, ON; Oleg Safir, ON; David
Backstein, ON; Allan E Gross, ON
Purpose: Long term outcomes of cemented and uncemented cups were compared in patients
with hip dysplasia that had previously undergone revision hip arthroplasty. In the indexed
revision hip arthroplasty all the patients had an uncontained superolateral acetabular defect
which was reconstructed with a structural allograft.
Method: In this retrospective study long term outcomes of cemented and uncemented
acetabular cups were compared. Thirty-nine patients (46 hips) included in this study had
previous hip dysplasia and had undergone a hip arthroplasty which failed due to loosening.
Inclusion criteria for the study were previous dysplasia, a superolateral acetabular rim defect
which was reconstructed with a shelf allograft at the time of revision hip arthroplasty. Nineteen
cemented acetabular cups were compared to 27 uncemented acetabular cups. Average followup was 210 months (range, 96-305) in the uncemented group and 253 months (range, 162312) in the cemented group. The average age at surgery was 52 years in the uncemented
group and 54 years in the cemented group. The primary outcome assessed was failure and
revision of the acetabular cup. Secondary outcomes were failure of the shelf grafts.
Survivorship analysis was calculated with Kaplan-Meier curves and Log-rank analysis was
used to compare the survival.
Results: At an average follow-up of 221 months, 18 acetabular cups (39%) failed due to
loosening and were revised. The 10, 20 and 25 year cup survival was 88%, 76% and 76% in
the uncemented group and 68%, 51% and 24% in the cemented group. Log rank analysis
showed a significant difference (P value 0.0172) between the two groups with regard to
implant survival. Only one shelf graft was revised.
Conclusion: Uncemented acetabular cups performed significantly better than cemented cups
in dysplastic hips after revision arthroplasty and an uncontained acetabular defect which was
reconstructed a shelf allograft.
119: The Mid-term Outcome of 75 Consecutive Constrained Acetabular Components in
Total Hip Arthoplasty
Robert Fassina, ON; Richard McCalden, ON; James L Howard, ON; Douglas Naudie, ON;
Steven JM MacDonald, ON; Robert B Bourne, ON
Purpose: Instability following total hip arthroplasty (THA) continues to be problematic for both
surgeon and patient. The use of constrained acetabular liners are most commonly used in the
salvage situation when other soft tissue tensioning techniques or implant options have failed to
offer adequate stability. The purpose of this study is to prospectively evaluate the mid-term
outcomes of a single design (Stryker/Osteonics) constrained acetablular component in the
management of instability following THA.
Method: Between 1994 and 2011, 75 Styker/Osteonics constrained acetabluar liners were
inserted and followed prospectively in 75 patients. The vast majority were performed as
revision surgeries having at least one prior arthroplasty. The main reason for revision was
instability (greater than 50%) although included two-stage revision for infection, aseptic
loosening, osteolysis, periprosthetic fracture and conversion from bipolar hemiarthroplasty.
Constrained liners were performed as the primary arthroplasty procedure in eight cases. Seven
of these were performed following failed fixation of neck of femur fractures and one in a patient
with muscular dystrophy with osteoarthritis. Patients were followed prospectively using
validated clinical outcome scores (WOMAC, SF-12, Harris Hip scores) and radiographs.
Kaplan-Meier survival analysis was performed.
Results: Mean follow-up was 36 months (range, 1.5- 108 months). Ten of the patients had
died with out adequate radio-clinical follow-up although none had undergone further revision.
Of the remaining patients, WOMAC and Harris Hip Score were significantly improved from
preoperatively to last follow-up (64.9 and 77.4 respectively). To date, five revision procedures
have been performed. Only one revision was performed for ongoing instability in a case where
the capture mechanism had failed. One revision was performed for aseptic loosening, two
revisions for pelvic dissociation following a fall and concurrent acetabular fracture, and one
revision for septic loosening. Kaplan Meier survivorship analysis of the capture cup system
with revision for dislocation as the outcome was 98.6% (97.2 to 100%) at 5 years and for
revision for any reason was 91.1%(87.6 to 94.6%) at 5 years. Excluding revision for infection
survivorship was 93.9% (90.9 to 96.9%) at 5 years.
Conclusion: The Stryker/Osteonics constrained acetabular component offered reliable fixation
and joint stability in patients with known and potential instability of their total hip arthroplasty.
120: Total Hip Arthroplasty after Chiari Pelvic Osteotomy
Nemanja Slavkovic, Anica Bitenc Fellow (Serbia)
Purpose: Karl Chiari introduced specific dome pelvic osteotomy in the 1950s. In the next three
decades he repeated same surgical procedure more then 2000 times without any changing.
Chiari pelvic osteotomy became very popular and wide performed. Original surgical technique
is modificated and improved during the time. Nevertheless, the basic idea is left unchanged –
increasing of the femoral head coverage by medial displacement of the distal part of the pelvis,
including hip, along with capsular interpositioning.
Method: Chiari pelvic osteotomy has lost its actuality and importance during this past six
decades. The role of Chiari pelvic osteotomy has been significantly taken over by other, more
efficient and more lasting surgical procedures. Nevertheless, Chiari pelvic osteotomy is still
present in modern orthopedic practice, above all as “salvage” osteotomy.
Results: Chiari pelvic osteotomy changes biomechanical features of the hip joint and may
compromise subsequent total hip arthroplasty or make it far more difficult. I evaluated
outcomes of patients with dysplastic hips treated at Institute for Orthopaedic Surgery “Banjica”
with total hip replacement after Chiari pelvic osteotomy. Patients charts and radiographs were
available and reviewed. I analyzed position of the acetabular endoprosthesis component, all
perioperative complications and causes for acetabular and femoral component revisions.
Conclusion: Alterations in Harris hip score and endoprosthesis survivorship were analyzed
regarding some radiographic parameters (the angle of the osteotomy, the distance of the
osteotomy from the acetabular edge and the percentage of medial displacement of inferior
pelvic fragment at the level of osteotomy).
121: A Comparison of Bone Geometry and Microstructure Between the Dominant and
Non-dominant Radius of Children
Kishore Mulpuri, BC; Jeanie Zabukovec, BC; Firoz Miyanji, BC; Chris Reilly, BC; Heather
Macdonald, BC; Christa Hoy, BC; Douglas Race, BC; Meghan Donaldson, BC; Heather
McKay, BC
Purpose: There is a positive relationship between physical activity and bone mass. Using
imaging systems such as peripheral quantitative computed tomography (pQCT) and dualenergy X-ray absortiometry (DXA), recent studies quantified significant differences in bone
geometry and bone mineral density or content between dominant and non-dominant hands
and humeri. Whether differences also exist in children and for bone microstructure has yet to
be determined. Should they be present, deficits may contribute to fractures which represent
about 10-25% of all pediatric trauma. Therefore the purpose of this study was to compare bone
microstructure in the dominant versus non dominant radius in children.
Method: We used high-resolution pQCT (HR-pQCT) to assess cortical density, cortical area,
cortical thickness, total density, total area, as well as trabelcular area, density, number,
separation and thickness. All measures were acquired at the 7% site of left and right radii. We
assessed n=79 children (aged 8-14y), 68 were right hand dominant (M=35, F=33; age=
12.1±1.66y, BMI= 19.5±3.98) and 11 left hand dominant (M= 3, F= 8; age= 11.09±1.26y, mean
BMI= 19.3± 2.96). (All mean±SD)
Results: Cortical area and cortical thickness were approximately 13% greater in the dominant
versus non dominant radius (16.52mm^2± 10.89 vs. 14.34 mm^2± 10.89; and
0.2743mm±0.178 vs. 0.238mm± 0.183, respectively) (p=0.003 both). There were no other
differences for any variable between dominant and non-dominant radii.
Conclusion: The increased loads experienced by the dominant arm significantly enhance
cortical bone geometry of the preferred side. This may offer some protection to the dominant
side or conversely place the non-dominant side at greater risk of fracture during a fall. The
structure of the cortex provides substantial strength to long bones. Thus, a smaller cortical
area and thickness in the non-dominant compared to the dominant radius supports (in part)
evidence of an increased fracture rate in the non-dominant arm in this young population.
122: Acute Kidney Injury in the Pediatric Intensive Care Unit following Spinal Surgery: A
Retrospective Study
Cherry Mammen, BC; Abdullah Alabbas, BC; Kishore Mulpuri, BC; Christopher S Reilly, BC;
Peter Skippen, BC
Purpose: Acute kidney injury (AKI) has replaced the earlier term, acute renal failure. AKIN
(Acute Kidney Injury Network) classification system has been developed to allow a comparison
between different studies and populations. AKIN consists of three severity stages: one (mild),
two (moderate), and three (severe), based on specified changes in serum creatinine (S.Cr)
compared to baseline or the duration of reduced urine output (UO). A recent adult study
revealed an AKI incidence of 16% following hip fracture surgery, however there is no literature
investigating the potential of children undergoing spinal surgery. The purpose of this study was
to 1) define incidence of AKI in patients admitted to the Pediatric Intensive Care Unit (PICU)
following spinal instrumentation surgery and 2) describe the clinical characteristics of these
children utilizing the AKIN definition.
Method: This is a retrospective, single center observational design. We included all postoperative spinal surgery admitted to our PICU between January 2006 and December 2008
with AKI defined by their maximal AKIN stage (UO or S.Cr criteria). Patient data was collected
from a PICU database and medical charts.
Results: We identified 23 out of 169 post-spinal surgery children with AKI. PRISM III (Pediatric
Risk of Mortality Score) was low with a mean of 5±3.8. Ten (43%) needed invasive ventilation.
The mean PICU length of stay was 3.17±2 days. 14 (61%) patients were given NSAIDs (mostly
IV Ketorolac) while four (17.4%) received aminoglycosides. The mean weight and baseline
S.Cr were higher in the idiopathic scoliosis (n=13) group (57.4±11.5 kg and 55±11 umol/L
respectively) in comparison to the non-idiopathic group (eight cerebral palsy/neuromuscular,
one spinal stenosis and one spondylolisthesis) with mean 47.8±23.3 kg and 34.3±15 umol/L.
The mean total IV fluids (cc/kg/day) given on the first day of surgery was lower with worsening
severity of AKI (130±61 (stage one) vs 60±17.5 (stage two) vs 52 (stage three)). Baseline
serum sodium increased from mean 140±2.5 to 144±3.3 mmol/L during PICU admission.
Seventeen (74%) patients had their AKI identified on the day of surgery. Almost all AKI (95%)
was defined by the AKIN UO criteria alone. None needed dialysis or died.
Conclusion: AKI incidence (14%) is common in this population. The use of nephrotoxic
medications was high (70% of patients). Severe AKI patients (stage two & three) were given
less fluids on the day of surgery as compared to those with milder injury (stage one). Serum
sodium rose to high-normal values in most patients. Most AKI patients were defined by the
AKIN UO criteria only and may have not been identified by the change in S.Cr criteria because
of the lower muscle mass associated with the non-idiopathic group. Relative dehydration is a
possible risk factor for AKI in this population. A larger prospective study is needed to confirm
the incidence and potential predictors for this group.
123: Do Surgical Wait Times affect Surgical Treatment and Peri-operative Management
of Patients with Cerebral Palsy and Subluxated or Dislocated Hips: The Surgeons
Kishore Mulpuri, BC; Megan S Cashin, BC; Henry Chambers, US; Benhamin Joseph, US;
Kerr Graham, VIC
Purpose: At our institution, many children wait more than one year for hip surgery for hip
subluxation/dislocation. The purpose of our study was to investigate the changes in severity of
hip subluxation/dislocation over time and how this might impact the type of surgery performed
and the associated peri-operative health resource utilization.
Method: 19 children who had waited a minimum of one year for surgical treatment of hip
subluxation or dislocation secondary to cerebral palsy were identified during an audit. The
children are patients at a tertiary children’s hospital. Two sets (AP and frog lateral) of
radiographs were selected for each patient at two different time points (38 total x-rays). These
radiographs and a questionnaire were sent to three pediatric orthopaedic surgeons
specializing in the hip. The surgeons were selected from three centers in three countries for an
international perspective. The surgeons were blinded to the fact that these radiographs were
from the same patients at two time points. The questionnaire requested information regarding
the type of surgery they would perform, peri-operative variables, and Graham Classification.
Results: The study group included 10 males and nine females. Mean age at baseline was 6.5
years. Average time between first and second x-ray was three years. Mean Reimers migration
percentage on baseline was 54.0 (95%CI 47.2, 60.8) and change in Reimers score between xrays was 26.0,(95%CI 0.3,51.7). Combining estimates of blood loss across the three surgeons,
at first x-ray the percentages in each category were: Less than 100 ml 28.1%, from 100 to 250
10.5%, between 250 and 500ml 36.8% and 500 to 1000 ml 14.0% with 6/19 cases not
estimated. At second x-ray, the estimates of blood loss for the same categories were 1.8%,
8.8%, 54.4% and 21.1% respectively. Mean length of surgery at time one was estimated to be
1.8 hours (95%CI 1.5, 2.1). At time two it was 2.3 hours (95%CI 2.1, 2.5) Mean estimate of
difficulty was 3.8 out of a score of 10 with 95%CI 3.2, 4.4. At follow-up the mean was 5.0 (95%
CI 4.6, 5.4). Graham Classification agreement was strong with 43/57 (75%) accuracy between
first and subsequent x-rays. Combining all surgeons’ observations, the kappa was 0.59,
considered to be excellent agreement.
Conclusion: From a surgeon’s perspective, waits of 12 months or more for CP hip surgery are
unacceptable as they lead to the need for a more complex procedure that probably would have
not been necessary had the operation occurred earlier. It also leads to increased operative
time, blood loss, length of stay, and difficulty of surgery. This, in turn, increases unwarranted
risks and costs. It is imperative that health policy decision makers’ work to reduce waiting times
for CP hip surgery, as increased waiting times have serious implications for the health of the
child as well as for costs to the healthcare system.
124: Does the Type of Distraction-based Growing System for Early Onset Scoliosis
Affect Post-operative Sagittal Alignment?
Ron El-Hawary, NS; Peter Sturm, US; Patrick Cahill, US; Amer Samdani, US; Michael Vitale,
US; Peter Gabos, US; Nathan Bodin, US; Colin Harris, US; Charles d'Amato, US; John Smith,
US
Purpose: Rib-based (RB) and spine-based (SB) posterior distraction growing systems are
commonly used for the treatment of early onset scoliosis (EOS). The purpose of this study was
to determine if the type of growing system affects post-operative sagittal-plane alignment.
Method: A multi-center, retrospective, IRB-approved radiographic comparison was performed.
Pre-operative and minimum 2-year follow-up radiographs were analyzed for a group of 79
children with EOS who were treated with posterior distraction-based implants.
Results: There were 56 subjects treated with rib-based and 23 subjects treated with spinebased systems. Mean pre-operative values for rib vs spine-based systems were: Age (4.4 vs
6.3 yr)*, Thoracic scoliosis (70.4° vs 74.8°), lumbar scoliosis (34.6° vs 40.1°), thoracic kyphosis
(36.6° vs 40.0°), and lumbar lordosis (45.7° vs 54.9°)*. Other than sacral slope (34.9° vs
39.7°)*, sagittal spinal and pelvic parameters were similar between groups.At minimum 2 yr
follow-up (3.5 yr RB vs 2.1 yr SB)*, curve correction was less for the rib-based group: 20.9% vs
47.5% thoracic* and 19.3% vs 48.9°% lumbar*. The rib-based group had greater cervical
lordosis (36.4° vs 21.4°)*, greater thoracic kyphosis (46.2 vs 26.0°)*, less lumbar lordosis (46.4
vs 53.5°), less sacral slope (34.8 vs 40.0°)*, greater pelvic tilt (18.0° vs 11.1°)*, and less pelvic
radius angle (49.8° vs 66.4°)*. Pelvic incidence was not different between groups. (* denotes
p<0.05).
Conclusion: Although longer follow-up for the rib-based group is a potential confounding
variable; at final follow-up, subjects treated with rib-based implants had greater cervical
lordosis, greater thoracic kyphosis, less lumbar lordosis, less sacral slope, greater pelvic tilt,
and less pelvic radius angle as compared to those treated with spine-based implants. Ribbased and spine-based implants result in different post-operative sagittal profiles. The patient’s
pre-operative sagittal alignment should be considered when deciding upon which type of
distraction-based growing system to use for an individual patient with EOS.
125: The Effects of Obesity on Deformity Correction in Adolescent and Juvenile
Idiopathic Scoliosis
Jochen Son-Hing, US; Christina K Hardesty, US; Connie Poe-Kochert, US; George H
Thompson, US
Purpose: Obesity is associated with an increased rate of complications in the peri-operative
period, especially in adults. An elevated body mass index (BMI) has been related to greater
preoperative thoracic kyphosis in children compared to those with a healthy weight. This
retrospective analysis was done to examine the relationship between BMI and surgical
outcomes in adolescent and juvenile idiopathic scoliosis.
Method: A retrospective review of our computerized pediatric spinal deformity database was
performed. Two hundred and thirty-six patients with idiopathic scoliosis underwent spinal
deformity correction surgery between 1992 and 2010. Demographic data, radiographic
measurements, intraoperative and postoperative data, and complications were collected. The
BMI was calculated for each patient. Pearson correlation coefficients were calculated to
evaluate the correlation between BMI and each of the outcome measures.
Results: Two hundred and thirty-six patients (187 females, 49 males) with an average age of
14.43 years (range 11-22 years) with a minimum of one year follow up met the inclusion
criteria for this study. The average BMI was 21.63 (range 10-46). The pearson correlation
coefficient was highest for preoperative thoracic kyphosis at 0.75. The correlation was lower
(0.25), for total operative time and amount of fluids given intraoperatively. The amount of
intraoperative blood loss, postoperative drainage, and total blood loss did not show any
significant correlation. The correction of deformity was also similar regardless of BMI. The
percent complication rate was much higher in the obese children (39%) compared to healthy
children (15%). Obese children were unable to receive a pre-operative spinal anesthetic 17%
of the time compared to 1% of the healthy children.
Conclusion: An increased BMI in adolescents and juveniles undergoing spinal deformity
surgery correlated strongly with increased preoperative kyphosis, number of postoperative
complications, and difficulty with administration of spinal anesthesia. An increased BMI
correlated less strongly with total operative time and amount of fluids required intraoperatively.
There was no significant correlation with intraoperative blood loss, postoperative drainage,
total blood loss, or correction of curvature.
126: Extension Type II Paediatric Supracondylar Humerus Fractures: Long Term Results
of Closed Reduction and Cast Immobilization
Scott Williams, NS; Tristan Camus, AB; Brent Maclellan, NS; Tricia Lane, NS; Kyleigh
Woods, NS; Ron El-Hawary, NS
Purpose: The treatment of Gartland type II supracondylar humerus fractures remains
controversial. It has recently been published that only half of these fractures treated with
closed reduction and cast immobilization achieved anatomical radiographic position and
alignment at short term follow-up. The purpose of this study was to determine the long term
clinical and radiographic outcomes of closed reduction and casting of extension type II
supracondylar humerus fractures.
Method: Patients who were treated for an extension type II supracondylar fracture at our
institution with a minimum of five-year follow-up were identified and invited to participate in the
study. We examined both radiographic and clinical outcomes in subjects for both their affected
and unaffected extremities.
Results: The average age of the 16 subjects at the time of injury was 5.3 years (1-9yr) and
their average follow-up was 9.6 years (6-16 years). Radiographic results for affected vs. nonaffected extremities: Anterior humeral line was central in 7 of 16 vs. 16 of 16 elbows ,
humerocapitellar angle was 51.7° (SD 7.4°) vs. 50.6° (SD 8.7°), Baumann’s angle was 81.0°
(SD 12.4°) vs. 79.6° (SD 6.2°), ulnohumeral angle was 4.3° (SD 6.3°) vs. 10.2 ° (SD 3.9°)
(p<0.003). Clinically, for affected vs. non-affected extremities: Active flexion was 148.7° (SD
7.4°) vs. 152.5° (SD 6.7°)(p<0.02), passive flexion was 154.3° (SD 7.9°) vs. 157.5° (SD 9.6°),
active pronation was 84.8° (SD 8.0°) vs. 86.4° (SD 6.7°), passive pronation was 96.3° (SD
10.0°) vs.97.3° (SD 9.6°), active supination was 98.8° (SD 13.9°) vs. 99.4°(SD 15.0°), passive
supination was 107.4° (SD 14.6°) vs. 110.0° (SD 15.6°), and carrying angle was 5.4° (SD 5.1°)
vs. 9.9° (SD 3.0°)(p<0.005). All subjects had satisfactory active and passive motion, while 14
of 16 subjects had satisfactory carrying angle using Flynn Criteria.
Conclusion: Long term follow-up of these patients demonstrated statistically significant
differences between affected and non-affected elbows for active flexion, carrying angle,
position of anterior humeral line, and the ulnohumeral angle. Despite these statistically
significant differences, the relative cubitus varus and mild limitation in flexion arc for the
majority of patients treated with closed reduction and casting are likely clinically insignificant.
127: Management of Distal Metaphyseal and Diaphyseal Radius/ Ulna Fractures in
Children
Presenter: Ritesh Khokhar
Purpose: We decided to evaluate the outcome (in terms of redisplacement and residual
deformity) of displaced distal metaphyseal and diaphyseal radius/ulna fracture treatment in
paediatric age group: Manipulation under anaesthesia (MUA) with plaster cast versus surgical
stabilisation (pinning).
Method: We conducted a retrospective analysis from case notes (Blue Spier electronic patient
data record system) and radiographs of 150 children aged 0 to 16 yrs with displaced distal
metaphyseal and diaphyseal radius/ulna fractures.
Results: 33 % of distal metaphyseal radius fractures redisplaced with majority (72%) in MUA
with cast group. Almost all redisplacements had associated ulna fracture. 43 % of these
displaced fractures underwent another procedure for correction of deformity. 15 % of
diaphyseal radius fractures redisplaced with majority (90 %) in MUA with cast group. Almost all
redisplaced diaphyseal radius fractures had associated ulna fracture. 10% of these displaced
fractures underwent further procedure for correction of the deformity. Complication rate with
pinning was very low (< 1%). No long term complication was encountered with pinning.
Conclusion: It is advisable to do pinning rather than MUA with cast only for displaced distal
metaphyseal and diaphyseal radius/ulna fractures requiring intervention.
128: Sagittal Spinopelvic Parameters Help Predict the Risk of Proximal Junctional
Kyphosis for Children Treated with Posterior Distraction Based Implants
Ron El-Hawary, NS; Peter Sturm, US; Patrick Cahill, US; Amer Samdani, US; Michael Vitale,
US; Peter Gabos, US; Nathan Bodin, US; Charles d'Amato, US; Colin Harris, US; John Smith,
US
Purpose: Rib-based (RB) and spine-based (SB) posterior growing systems are commonly
used for the treatment of early onset scoliosis (EOS). The purpose of this study was to
determine if pre-operative spinopelvic parameters can predict the risk of post-operative
proximal junctional kyphosis (PJK).
Method: A multi-center, retrospective, IRB-approved radiographic comparison was performed.
Pre-operative and minimum 2-year follow-up radiographs were analyzed for a group of 40
children with EOS who were treated with posterior distraction-based implants (24 RB, 16 SB).
PJK was defined as proximal junction sagittal angle (PJA) >/= 10° and PJA at least 10° greater
than preoperative.
Results: At a minimum of two year follow-up, 11 subjects (27.5%) developed PJK. Follow-up
time was not different between groups (2.4 yr PJK vs 2.9 yr No PJK); however, there was a
significant difference in age at time of initial surgery (7.1 yr PJK vs 5.0 yr No PJK)*. The rates
of PJK were similar between rib-based and spine-based growing systems (25% vs 31%). Preoperative radiographic comparisons between PJK vs No PJK: Thoracic scoliosis (69.9° vs
76.0°), lumbar scoliosis (38.8° vs 39.1°), thoracic kyphosis (45.1° vs 28.7°)*, thoracolumbar
kyphosis (3.6° vs 12.5°), lumbar lordosis (53.1° vs 44.0°), PJA (2.2° vs 2.8°), sagittal balance
(1.5 cm vs 2.6 cm), pelvic incidence (52.8° vs 47.4°), pelvic tilt (14.3° vs 8.7°), sacral slope
(37.7° vs 35.9°), pelvic radius angle (72.7° vs 67°).At final follow-up, differences were found for
cervical lordosis (30° vs 16.6°)*, PJA (21.9° vs 3.1°)*, sagittal balance (3.7 cm vs 0.2 cm)*, and
pelvic radius angle (79.1° vs 62.2°)* (* denotes p<0.05).
Conclusion: Higher rates of PJK were found for older children who were hyperkyphotic preoperatively and in those who had positive post-operative sagittal balance. Older age and preoperative hyperkyphosis may increase the risk of developing PJK. Strategies to intraoperatively restore normal sagittal balance may help avoid the development of PJK in children
treated with growing systems for EOS.
129: The Clinical Stability of Lateral Pinning in the Surgical Treatment of Supracondylar
Humeral Fracture with Medial Column Involvement in Children
Mathilde Hupin, QC; Louis-Philippe Charette, QC; Constantin Stanciu, QC; Stefan Parent,
QC; Jean-Marc Mac-Thiong, QC
Purpose: Previous biomechanical studies have been done to determine the stability of
different pinning configurations for fixating supracondylar humeral fractures in children when
there is medial column comminution or extension. However, no clinical study has been
conducted so far to evaluate the effectiveness of various pinning configurations when there is
involvement of the medial column associated with supracondylar humeral fractures in children.
The purpose of our study was to evaluate the clinical stability of the lateral entry pinning
techniques for unstable supracondylar humerus fractures in children with medial column
comminution or extension.
Method: We reviewed all Gartland type II/III supracondylar humerus fractures treated
surgically at a single paediatric institution from January first, 2002 to January first, 2011.
Patients were included in this study if they had: 1) involvement of the medial column as defined
by medial comminution or extension proximal to the olecranon fossa, and 2) treatment by
closed reduction followed by lateral percutaneous pinning. From all 412 patients reviewed, 17
aged 5.6 ±2.2 years (range: one-10 years) fulfilled the inclusion criteria and were kept for
further analysis. The Baumann’ angle and the capitellohumeral angle were compared between
the C-arm images taken at the time of surgery and the postoperative radiographs taken three
weeks after the surgery after the pin removal. Loss of reduction was defined as a change in
Baumann’s angle or in capitellohumeral angle of more than six degres and 10 degres
respectively.
Results: The Baumann’s angle and capitellohumeral angle were respectively 74±six degres
(median:75°; range:60-86°) and 44±15° (median:48°; range:16-72°) at the time of surgery.
After pin removal, Baumann’s angle and capitellohumeral angle were respectively 77±seven
degres (median:78°; range:77-90°) and 41±11° (median:41°; range:21-64°). According to our
predetermined criterias defining loss of reduction, 11 of our 17 patients (65%) had failed to
maintain the alignment.
Conclusion: In the current study, we have found that lost of reduction occurred in 65% of the
17 patients with supracondylar humerus fractures with medial column involvement. This
observation is in accordance with previous biomechanical studies suggesting the lack of
mechanical stability provided by lateral pinning only in the presence of medial column
comminution or extension. Clinicians should be aware of the significant instability related with
supracondylar humerus fractures in children with medial column involvement. Therefore, lateral
pinning only may not provided adequate clinical stability in these situations. Further studies
should be address comparing lateral and crossed pinning in operative treatment of these
fractures.
130: Use of Bipolar Sealer Device Reduces Blood Loss and Transfusions in Posterior
Spinal Fusion
Jochen Son-Hing, US; Zachary L Gordon, US; Connie Poe-Kochert, US; George H
Thompson, US
Purpose: Reducing perioperative blood loss and transfusions in patients undergoing posterior
spinal surgery is important. Since 2001, all our pediatric patients have received epsilon
aminocaproic acid (Amicar) to reduce perioperative blood utilization. To reduce blood loss and
transfusions further, we are using a bipolar sealer device (Aquamantys, Salient Surgical
Technologies) as an adjunct to electrocautery.
Method: Using a prospectively maintained database, we reviewed the operative time,
estimated blood loss, cell saver use, and intraoperative and postoperative transfusion rate in
patients who underwent posterior-only spinal fusion for idiopathic scoliosis. Fifty patients were
identified who fit these criteria since initial use of the bipolar sealer device. We compared these
patients to a control group of the preceding fifty patients for whom the device was not used. All
patients, including those in the study group, received Amicar (infusion of 100 mg/kg over 15 to
20 minutes, then 10 mg/kg per hour throughout the remainder of the procedure). The surgical
technique did not differ between the two groups.
Results: Baseline characteristics between the two groups were similar except for the number
of levels fused, which was larger in the investigational group (12.5 versus 11.8, p=0.027).
There was no difference in operative time or hospital length of stay. Intraoperative blood loss
was 597mL in the study group and 1085mL in the control group (p<0.0001). Total perioperative
blood loss, including postoperative drain output, was 1266mL in the study group and 1600mL
in the control group (p=0.01). Intraoperative cell saver transfusion was 127mL in the study
group and 200mL in the control group (p=0.001). Eleven patients in the study group and
twenty-six patients in the control group required additional intraoperative or postoperative
transfusions (p=0.004). The number of packed red cell units transfused per patient was 0.26 in
the study group and 0.58 in the control group (p=0.034), reducing the transfusion rate by over
50%. Total blood volume transfused, including cell saver, was also significantly lower in the
study group (212mL vs. 388mL, p=0.001).
Conclusion: Use of a bipolar sealer device significantly reduces total perioperative blood loss
and transfusion requirements, when compared with a control group in posterior spinal surgery
for idiopathic scoliosis.
131: A Comparative Study of Posterior Fixation in Acute Unstable Thoracolumbar
Injuries by Monoaxial and Polyaxial Pedicle Screws
Rajeshwar Nath Srivastava, IN; Pradeep Singh, IN
Purpose: The treatment of unstable thoracic spine fractures remains controversial. Theoretical
biomechanical advantages of transpedicular screw fixation include three-column control of
vertebral segments and fixation of a vertebral segment in the absence of intact post-erior
elements. Additionally, pedicle screw constructs may obviate the need for neural canal
dissection and potential neural element impingement by intracanal instrumenta-tion. A
prospective longitudnal study was done to compare posterior fixation in acute unstable
thoracolumbar injuries by monoaxial and polyaxial pedicle screws
Method: Thirty-eight cases formed the study group as per inclusion criteria. By random
allocation 18 patients were managed by polyaxial pedicle screw rod (PPSR) system-Gp A and
20 by monoaxial pedicle screw and rod system (MPSR) –Gp B.
Results: In Gp A, at 1 year follow up, 12/17 (66.6%) of AIS A remained at AIS-A, 2/17
(11.11%) recovered from AIS-A to AIS-B and 1 (5.55%) recovered from AIS-A to AIS-C. 2/17
(11.11%) patients were ambulatory at 1 year and had shown full neurological recovery AIS-A
to AIS-E. In Gp B, at 1 year follow up, 13/16 (81.25%) of AIS A remained at AIS-A, 2/16
(12.5%) recovered from AIS-A to AIS-B and 1/16 (6.5%) recovered from AIS-A to AIS-C. In Gp
A average kyphotic angle at admission was 32o which postoperatively was re-duced to 10.3o
with average correction being 21.7o, whereas in Gp B average Kyphotic angle was 26o at
admission which postoperatively was reduced to 9.6o with average correction being 16.4o.
Correction of 32.14 % and 35.5 % of vertebral height was achieved in Gp A and Gp B
respectively after surgery. At I year follow up, average kyphotic angle in Gp A was almost
same as in postoperative phase – 13.3o with a loss of 3o surgical correction. In Gp B, the
average kyphotic angle was 17.6o with a loss of 8o of surgical correction. This was found to be
statistically insig-nificant. The difference in the two groups was due to 3 implant failures in GP
B which resulted in gross loss of surgical reduction.There were 3 implant related postoperative
complication in patient fixed with monoax-ialpedicle screw (MPSR)-Gp B. In 1 the rod migrated
proximally on right side and in two others there was breakage of upper two pedicle screw
through neck. There was no im-plant failure in polyaxial screw rod system(PPSR)- Gp A. Rate
of implant failure accounted for 15% in Gp B and this was found to be statistically significant. At
1 year, 32/38 (85.2%) were on wheel chair ambulation, 2/38 (5.26%) were walking with support
and 4/38 (10.5%) were ambulatory without any aid.
Conclusion: There was no significant difference in neurological recovery, pain function scores
and ambulatory status in the two groups.The polyaxis facilitates surgical procedure and
reduces surgical time and blood loss. Polyaxial pedicle screw is superior to monoaxial in trems
of reduction, stability and implant failures.
132: Comparison of the Effectiveness of Short Course Chemotherapy with Conventional
Treatment for Spinal Tuberculosis
Rajendra Kumar, IN; Pranay Bhushan, IN
Purpose: There is a lack of availability of a standard regimen for treatment of osteoarticular
tuberculosis. As a consequence of the low incidence of osteoarticular tuberculosis in western
world there is a lack of controlled trials studying the osteoarticular form of disease. From a
public health perspective too, extra pulmonary osteoarticular tuberculosis is not of great
importance, because patients with this form of disease are not infectious, unless they have
pulmonary involvement. Though WHO protocol short course chemotherapy is a standard
recommendation for all countries, it is not being universally followed. Various workers across
the world have recommended different duration of chemotherapy for an effective management
of spinal Tuberculosis. With the ongoing research in the various aspect of spinal tuberculosis
for over 5 decade now, no definite consensus is still achieved for the treatment protocol, like
what drug, what regime, what duration of treatment. AIM: To compare the efficacy of WHO
regime to conventional treatment (middle path).
Method: Between January 2001 till May 2010, 202 cases of newly diagnosed Spinal
tuberculosis were included in this prospective study. Of which 88 cases were treated by
conventional middle path regime, and 114 cases were treated according to WHO regime
(2HRZE+4HR). The average duration of follow up was 4 years (2 – 9 years).
Results: Overall incidence was found to be higher in females (56%), with maximum number
cases in the age group of 11-40 years, and mean age of presentation being 32 years. Pain
was the most common symptom (95%) followed by constitutional symptoms (56%), and
abscess (33). Thoracic involvement being more common in males and lumbosacral more
common in females. ESR was taken as a useful, was found elevated in 92% cases. Results
were evaluated using clinical, haematological, and radiological evidences. MRI used as early
diagnostic tool in both the groups and for follow up. All cases treated with middle path regime
had good response and showed healing in 85%cases which is statistically highly significant (P
value<0.001), whereas short course chemotherapy was found sufficient in 79% cases
(P<0.001) , again highly significant. There were no cases of MDR tuberculosis in the
conventional treatment group, where as there were 4 cases in the short course chemotherapy
group ( non significant).there were no relapse in the two groups.
Conclusion: This experience showed medical management is the main stay for treatment in
spinal tuberculosis. Patients should be treated as per WHO Short course chemotherapy, but
treatment can be suitably extended in cases.
133: Effect of Motor Score on Adverse Events and Quality of Life in Patients with
Traumatic Spinal Cord Injury
John T Street , BC; Vanessa Noonan, BC; Antoinette Cheung, BC; Brian Sun, BC; Marcel
Dvorak,
BC
Purpose: Neurological impairment associated with traumatic spinal cord injury (tSCI) results in
significant health care costs and disability. The purpose of this study was to assess the impact
of neurological impairment, specifically motor score on admission with the incidence of adverse
events, length of stay (LOS) and long-term health status in patients with tSCI.
Method: Patients with a tSCI from one centre were recorded in a prospective registry between
2008 and 2010. Adverse event data was prospectively collected using the Spine Adverse
Events Severity instrument. Data related to patients’ injury, diagnoses, hospital admission, and
follow-up Short Form-36 (SF-36) Physical and Mental Component Scores (PCS, MCS) were
obtained from the Registry. The five most common adverse events were identified and
multivariate analyses were performed to determine whether the initial motor score on
admission was significantly associated with each adverse event, as well as with LOS and SF36 scores at 1 to 2 years post-injury.
Results: 171 patients with tSCI were included, 81.3% were male and the mean age at injury
was 47.2±20.3 years. A lower motor score on admission was significantly associated with
having pneumonia, pressure ulcers and urinary tract infections (p<0.05); no association was
found with delirium or neuropathic pain. There was also a significant association between
motor score and the incidence of adverse events and LOS (p<0.0001). For each 10 point
decrease in motor score, LOS increased by 20%. In patients with a motor score over 50, the
SF-36 PCS increased by 3.8 for each 10 point increase in motor score. There was no effect on
the SF-36 MCS.
Conclusion: The initial motor score can predict important outcomes such as incidence and
type of adverse events, LOS and long-term health status. Patients with low motor scores
should be identified on admission to maximize their health outcomes.
134: MRI in Spinal Trauma – A Predictor of Neurological Recovery
Rajeshwar Nath Srivastava, IN; Umesh Parasri, IN
Purpose: Use of Magnetic Resonance Imaging appears to be of great help in diagnosing
spinal trauma & correlating it with clinical profile & neurological outcome because of better
contrast resolution, absence of bony artifacts, multiplanar imaging and choice of pulse
sequences. In cases of spinal cord ischemia, hemorrhage, edema, and contusion. A study
was done to correlate MRI findings with neurological recovery and functional outcome in spinal
cord injury
Method: We performed this prospective study on sixty two patients of acute spinal trauma. We
evaluated the epidemiology of spinal trauma & various traumatic findings by MRI. Then the
MRI findings were correlated with clinical findings at admission & discharge according to ASIA
impairment scale. Four types of MR signal patterns were seen in association with spinal cord
injury- cord edema / non haemmorhagic cord contusion (CC), severe cord compression (SCC),
cord hemorrhage (CH) and epidural heamatoma (EH). Isolated lesion of cord contusion was
found in 40%. All other MR signal patterns were found to be in combination. In cord contusion
we further subdivided the group into contusion of size < 3 cm and contusion of size > 3 cm to
evaluate any significance of length of cord contusion. In cord heammorhage involving >1cm of
the cord, focus was said to be sizable
Results: On bivariate analysis, there was there was a definitive correlation of cord contusion
(CC) involving <3cm & > 3cm of cord. In >3cm chances of improvement was 5.75 times lesser
than in patients with CC involving <3cm of cord (odds ratio = 5.75 (95% CI: 0.95, 36), Fisher’s
exact p = 0.0427 (p<.05). Presence of sizable focus of haemorrhage (HC) in cord (>1cm) was
most strongly associated with the poor outcome. The risk of retaining a complete cord injury at
the time of follow up for patients who initially had significant haemorrhage in cord was more
than 6 folds with patients without initial haemorrhage (odds ratio 6.97 and p= .0047). It was
noted that the patients in which epidural hematoma (EH) was present, no improvement was
seen, however, by statistical analysis it was not a risk factor and was not related with the
outcome (odds ratio – 0.5 and p = 0.22). Presence of severe cord compression (SCC) was a
risk factor for poor outcome (odds ratio – 4.90 and p = 0.0143)
Conclusion: On multiple logistic regression / multivariate analysis for estimating prognosis,
sizable focus of hemorrhage was most consistently associated with poor outcome (odds ratio 6.73 and p= 0.32). In severe cord compression the risk of poor outcome was more (odds ratio
4.3 and p=0.149) however was not statistically significant. Presence of cord oedema / non
haemorrhagic contusion was not associated with poor outcome (odds ratio 0.25 and p=0.178)
The risk of retaining a complete cord injury at the time of follow up for patients who initially
showed evidence of significant haemorrhage in cord was more than 6 folds with patients
without initial haemorrhage(Odds ratio – 6.97 and p = 0.0047).
135: No Orthosis is Equivalent to TLSO for the Treatment of Thoracolumbar Burst
Fractures Without Neurologic Injury: Results from a Multi-centred RCT
Christopher S Bailey, ON; Marcel F Dvorak, BC; Kenneth C Thomas, AB; Melissa Nadeau,
ON; Kevin R Gurr, ON; Stewart I Bailey, ON; Charles G Fisher, BC
Purpose: To compare the functional outcome of patients with AO type A3 burst fractures
randomly treated with a TLSO versus no orthosis (NO).
Method: Study design/setting: A multi-centred prospective randomized controlled equivalence
trial. Patient sample: Patients were recruited from three Canadian tertiary spine centres.
Outcome measures: The primary outcome measure was the Roland Morris Disability
Questionnaire (RMDQ) assessed at 3 months post injury. Secondary outcomes were assessed
at 2, 6, 12, 24, 52 and 104 weeks and included: pain (Visual Analogue Scale), functional
outcome (RMDQ), generic health related quality of life (SF-36), patient satisfaction, sagittal
alignment, length of hospital stay and complications. Consecutive patients who satisfied the
following inclusion criteria were considered eligible for this study: 1) AO-A3 burst fractures
between T11 and L3, 2) skeletally mature and less than sixty years of age, 3) admitted to the
participating hospital within seventy-two hours of their injury, 4) initial kyphotic deformity of less
then thirty-five degrees, 5) no neurologic deficit. Randomization was stratified according to
worker’s compensation status and severity of kyphosis at admission (<20° versus ≥20°).
Enrollment continued until the sample size satisfied a power of 90%. The NO group was
encouraged to ambulate immediately following randomization with bending restrictions for
eight weeks. The TLSO group was weaned from the brace between the eight to ten week
period. Both groups were encouraged to perform a standardized physiotherapy routine.
Results: 47 patients were enrolled into the TLSO group and 49 patients into the NO group.
The mean subject age was 40 years and 70% were male. The majority of fractures occurred at
L1 (49) then T12 (18) and L2 (15). At the three month primary endpoint 46 patients were
evaluated in each group. There was no difference in average length of hospital stay (TLSO =
4.7 days, NO= 5.0 days). No difference was found between groups for any of the primary or
secondary outcomes at any of the follow-up periods (student t-test). One way analysis of
variance identified a significant improvement of the RMDQ within both groups at 6 weeks and
at 3 months for the NO group (p<0.05) but not afterward. The average kyphotic deformity was
14° (range: -1 to 35) at admission that increased to 21° at 6 weeks and did not progress
further. No difference existed between treatment groups. Six patients required surgical
stabilization, five of these prior to initial discharge.
Conclusion: Neurologically intact thoracolumbar burst fractures can be successfully treated
using early ambulation without a brace.
136: Percutaneous Thoracolumbar Stabilization for Trauma: Surgical Morbidity, Clinical
Outcomes and Revision Surgery
Neil Manson, NB; Renee Elliott, NB; Melissa McKeon, NB; Edward Abraham, NB
Purpose: Percutaneous pedicle screw-rod instrumentation (PercStab) without direct
decompression or fusion is a surgical option to manage thoracolumbar trauma. The current
standard of care includes instrumentation removal following osseoligamentous healing. It is
hypothesized that instrumentation removal is not required following PercStab. The purpose of
the present study is to evaluate the utility of PercStab in the following areas: 1) patient
satisfaction, 2) return of function 3) need for repeat surgery including instrumentation removal
or revision decompression and/or fusion procedures.
Method: A retrospective review of a prospective database identified patients receiving
PercStab for trauma from January 2007 to August 2011. TLICS scoring criteria (Spine Trauma
Study Group) identified surgical candidacy. Validated clinical outcome measures, patient
demographics, perioperative data, and the need for further surgery were assessed via clinic
follow up, chart review, and telephone interview. Medians and ranges were reported. Outcome
measures intra-op consisted of OR time/level, EBL/level and intraoperative complications.
Post-op complications and LOS were analyzed in addition to VAS back and leg pain scores,
Oswestry Disability Index (ODI), Likert-type questionnaire and return to work (RTW) and
normal activities.
Results: Twenty-six trauma patients with a median Injury Severity Score of 10 (9 – 41)
received PercStab to treat spinal instability over two levels (range 1-5) and were contacted for
follow-up 24 months (2 months - 4.5 years) post-surgery. Minimal surgical morbidity was
incurred: OR time: 36.5 (25 – 63.5) minutes / level, blood loss / level: 40 (12.5 – 250) cc, time
post op to hospital discharge: six (1 – 37) days. Patients reported satisfaction: VAS back: 2 (0
– 8), VAS leg: 1 (0 – 7), ODI: 16 (0 – 54), three months (two weeks – six months) to return to
work or regular activities. Patients scored a median outcome satisfaction of 5 (3.75 – 5) out of
5 on a likert-type questionnaire. Only 4/26 (15%) of patients required instrumentation removal:
two for screw loosening causing back pain and two thin patients for screw prominence causing
discomfort with direct pressure. The remaining 22/26 (85%) of patients had no symptoms or
complications related to the implants and there was no need for revision surgery for posttraumatic deformity, pseudarthrosis or infection.
Conclusion: The PercStab surgical option for spine trauma provides rapid mobilization and
discharge from hospital, medium-term satisfaction, with minimal surgical morbidity. The
majority of patients returned to work and normal activities on average 3 months post
operatively. Instrumentation removal can be considered on an individual basis. No operative
procedures were required for post-traumatic deformity, pseudarthrosis or infection. Further
research is required to quantify the utility of this technique in comparison to traditional surgical
options.
137: Potential of Parathyroid Hormone for Suppressing Calcification in Human
Intervertebral Discs and Promoting Repair
Padma Madiraju, QC; John Antoniou, QC; Fackson Mwale, QC
Purpose: Intervertebral disc (IVD) degeneration is associated with ongoing mineral deposition.
The presence of calcium deposits, type X collagen (COL X) and the level of indicators of
calcification potential (alkaline phosphatase (ALP), Ca2+ and Pi) are consistently higher in
degenerative and scoliotic discs than in control discs. In mesenchymal stem cells parathyroid
hormone (PTH 1-34) is able to inhibit the expression of COL X while promoting COL II
expression, thereby preventing endochondral ossification. The purpose of this study is to
investigate the effect of PTH on the expression of COL II, COL X and ALP in human IVD cells
and to elucidate the mechanisms related to its effect.
Method: Isolation and culture of IVD cells: Human lumbar IVDs from a donor without spinal
pathology were obtained within 24h after death. The procedure was approved by institutional
research ethics committee. Nucleus pulposus (NP) and annulus fibrosus (AF) tissues from the
IVDs were digested and the corresponding NP and AF primary cells were isolated. These cells
were cultured in complete DMEM to 80% to 90% confluence. Then the cells were incubated
overnight in serum free medium and treated with 100nM PTH for 30 min to 48h. The cell
lysates were prepared and total protein in the cell extracts was determined. Protein expression
was analysed by immunoblotting. Western blot images were quantified using ImageJ (NIH)
software. The release of Ca2+ into the medium was measured using Calcium assay kit
(Cayman Chemicals). ALP activity was measured using the StemTAG kit (Cell Biolabs).
Statistical analyses were by One-way ANOVA, post-hoc test.
Results: PTH increased the expression of COL II significantly in both AF and NP cells in a
time-dependent manner, from 6 to 48h. Expression of COL X was not altered in AF cells,
whereas it decreased in NP cells from 6 to 48h. However, the activation of MAPKs occurred
much earlier, by 30min incubation with PTH in both cell types. PTH significantly decreased
ALP activity by 24h in NP cells, whereas in AF cells no significant changes were observed.
PTH caused a significant increase in Ca2+ release by 48h in NP cells but not in AF cells.
Conclusion: PTH is known to promote chondrogenesis and inhibit COL X expression in
chondrocytes via MAPK activation. The present results demonstrate that PTH up-regulates
COL II and down-regulates COL X in IVD cells, indicating that PTH has the potential of being
able to stimulate disc repair and improve nutrient supply in the degenerative disc. Our data
also suggest that MAPK activation takes place much earlier than the alterations in COL II or
COL X expression. Interestingly, COL II expression inversely correlates with ALP activity in NP
cells treated with PTH. A thorough understanding of IVD calcification would be of great value,
not only for elucidation of its mechanism, but with an eye toward eventual therapeutic
intervention. PTH can thus be used towards disc regeneration therapy.
138: Spinal Shock in Spinal Cord Injuries - Is Duration of Shock Related to Neurological
Level ?
Rajeshwar Nath Srivastava, IN; Sanjeev Arya, IN
Purpose: The definition & etiology of spinal shock remain controversial. The factors
influencing this duration and its clinical significance are not well studied. A study was
undertaken to study the duration and the factors influencing spinal shock.An arithmetical
relationship was seen to exist between the duration of spinal shock and the segmental level of
spinal cord injury. A study was done to determine the duration of spinal shock in spinal cord
injury (SCI), the first reflex to return while recovering from spinal shock & the factors
influencing duration of spinal shock
Method: 116 patients in spinal shock following SCI were included. A detailed neurological
examination of sensory, motor and reflex activity was done everyday till the patients were out
of spinal shock. The duration of spinal shock by appearance of any reflex, the first reflex to
return & the influence of variable factors on duration of spinal shock were studied
Results: In 76 patients (85.4%) anal wink (AW) was the first reflex to return either alone or
simultaneous with BC / DPR.In 7 patients cremastric reflex, in 3 pathological reflexes & in 2
deep tendon reflexes ( ankle) were the first to return. Mean duration of spinal shock (MD of SS)
was shorter in children, shorter in malnourished, shorter in untrained/laborers, shorter in
patients admitted early and shorter in patients without any complications. "MD of SS" was not
influenced by sex of patient, associated injuries and by different modalities of treatment
Conclusion: On statistical analysis of duration of spinal shock with neurological level as a
variable "MD of SS "was 1.7 days in cervical cord lesions, 8.2 days in upper thoracic, 15 days
in lower thoracic and 17 days in lumbar cord lesions. Such an arithmetical progression was
also found at each segmental level i.e. the duration of spinal shock progressively increased at
every segmental level. "MD of SS" was 1.36days at C4, 1.60 at C5, 1.72 at C6, 8.1 at T6, 12.4
at T8, 13.1 at T10, 15.3 at T12 & 21.6 at L2. An arithmetical relationship exist between the
duration of spinal shock and the segmental level of spinal cord injury - the duration of spinal
shock was directly proportional to level of injury. Higher or proximal the lesion, shorter is the
duration. We do not have the answer of this important observation. Does the duration of spinal
shock dependant on the cord length / neuronal mass involved / spared?
139: The Effect of Timing to Decompression in Cauda Equina Syndrome Using a Rat
Model
Christopher S Bailey, ON; R Andrew Glennie, ON; Jennifer Fleming, ON; Kevin R Gurr, ON;
Stuart Bailey, ON; David Sanders, ON; Abdel R Lawendy, ON
Purpose: Cauda Equina syndrome is a devastating injury for which surgery is the only
treatment option, however, controversy exists regarding the optimal timing of surgery. Clinical
studies have investigated the effect of the timing of surgical decompression for motor recovery,
but no definitive recommendations exist. The effect on bladder function and sensation has
been sparsely investigated. The purpose of this study was to determine the effect of duration
of extra-dural cauda equina compression on bladder, sensory, and motor dysfunction using a
rat model.
Method: Under general anesthesia a balloon-tipped Fogerty catheter (2 mm diameter) was
inserted underneath the 5th and 6th lumbar vertebral bodies and inflated to rapidly compress
the cauda equina. A three-way stopcock allowed pressure monitoring to ensure consistent
extra-dural compression of 250 mmHg. The compression was maintained for 1 h or 4 h at
which time the balloon was deflated, representing surgical decompression. Sham animals had
the catheter inserted underneath the vertebral bodies, but the catheter was not inflated. Over a
four week period pain scores, urinary residual volumes, and locomotor function were
assessed. Post mortem, bladders and kidneys were collected for analysis.
Results: Final bladder pressure and bladder weights were greater in the 4h compression
group versus the 1 h compression group (p<0.05). Pain scores were greater for 1 hr CES rats
and remained consistently elevated to the end of the protocol. The locomotion data could not
detect a difference gait coordination between all groups.
Conclusion: Our data suggest that motor function after urgent or delayed decompression will
likely lead to full recovery. Bladder functional recovery is much less predictable and seems to
be very sensitive to longer durations of compression. This has significant implications on
patients presenting with acute cauda equina syndrome and how to proceed if these symptoms
are identified.
140: Use of the Spine Adverse Events Severity (SAVES) Instrument for Traumatic Spinal
Cord Injury
John T Street, BC; Vanessa Noonan, BC; Antoinette Cheung, BC; Brian Sun, BC; Marcel
Dvorak, BC
Purpose: Adverse events are common during the acute phase of care in patients with
traumatic spinal cord injury (tSCI). Administrative data is often used to report adverse events
however this data may not reflect patient outcomes. The Spine Adverse Events Severity
(SAVES) instrument was developed for clinicians to record adverse events. The objective of
this study was to determine if the SAVES was superior to ICD-10 codes in measuring adverse
events in patients with tSCI.
Method: Patients discharged between 2006 and 2010 were identified from a prospective
registry. Two cohorts were created based on the method used to record adverse events;
Cohort 1 used ICD-10 codes and Cohort 2 used SAVES data. The ICD-10 codes were
mapped to adverse events in SAVES. Five adverse events were examined: neuropathic pain,
urinary tract infections (UTI), pneumonia, pressure ulcers and delirium. There were 212
patients in Cohort 1 and 173 patients in Cohort 2. Analyses were adjusted to account for the
different sample sizes and the two cohorts were comparable based on age, gender,
mechanism of injury and motor score.
Results: There was an 18% increase in the number of patients diagnosed as having one or
more adverse events using SAVES (76%) compared to ICD-10 codes (58%). The number of
adverse events per person more than doubled using SAVES (1.3 versus 2.7). The SAVES
reported greater incidence of neuropathic pain (x32), UTI (x1.4), pneumonia (x1.2), pressure
ulcers (x2.9) and delirium (x1.2). The number of intra-operative adverse events obtained was
2.3 times greater using SAVES (7.5% versus 17.3%).
Conclusion: The implementation of SAVES among patients with tSCI captured more patients
experiencing adverse events and more adverse events per person compared to using ICD-10
codes. This study demonstrates the value of prospectively collecting data on adverse events.
141: Ability of Pre-Season Body Composition & Physical Fitness to Predict Risk of
Injury in Male Collegiate Hockey Players
John A Grant, US; Asheesh Bedi, US; Jennifer Kurz, US; Richard Bancroft, US; Joel J
Gagnier, US; Bruce S Miller, US
Purpose: Injuries in collegiate ice hockey can result in significant time lost from play. On
average, the combined lost time for all players injured in one year is equal to the loss of one
player for almost the complete season. The identification of modifiable risk factors relating to a
player’s physical fitness allows the development of focused training and injury prevention
programs targeted at reducing these risks. No studies have evaluated the risk of on-ice injury
relative to modifiable risk factors such as a player’s conditioning level, strength and/or body
composition. The purpose of this study was to determine the injury rate for male collegiate ice
hockey and determine the role of pre-season fitness measures in predicting an on-ice injury.
Method: A case control study was performed using data prospectively collected by one male
collegiate ice hockey team over the past 8 seasons. There were 79 different players and 203
player-years. Athlete demographics, percent body fat), aerobic endurance (300m shuttle run;
1, 1.5, 5 mile run), and strength assessment (sit-ups, push-ups, grip strength, bench press,
Olympic cleans, squats) data was collected at the beginning of each season. Detailed hockeyrelated injury data and player-level practice/game athlete exposure (AE) data was collected
and entered by the team Athletic Trainer. Injury was defined as any event that resulted in the
athlete being unable to participate in one or more practices or games following the event.
Descriptive statistics were performed. Single and multiple variable logistic regression was
performed to determine the ability of the independent variables to predict the risk of on-ice
injury. Given that athletes played multiple years, “athlete” and “year” interaction variables were
entered into the models.
Results: There were a total of 132 injuries (mean 16.5 per year, range 12-21). The overall
injury rate was 4.4 injuries per 1000 AE (yearly range 3.2-6.1/1000 AE). Forwards suffered
68% of injuries. Seventy percent of injuries occurred during games with equal distribution
between the three periods. The mean number of days lost due to injury was 10.8±21.6 (range
1-135). The thigh/hip (21%) and shoulder (20%) were the most common body areas of injury.
The most common mechanism of injury was contact with another player (60%). The odds of
injury in a forward was 1.9x that of a defence and 3.0x that of a goalie. The odds of injury if the
player’s BMI was ≥25 was 2x that of a player with a BMI <25. The odds of injury increased by
2.7x for each increase of 5% body fat. There were no strong predictors of injury amongst the
aerobic and strength variables.
Conclusion: Forwards have a higher odds of injury relative to other player positions. BMI and
percent body fat were predictive of on-ice injury. Aerobic fitness and maximum strength
outcomes were not strongly predictive of on-ice injury. The use of more sport specific
aerobic/strength measures should be evaluated for their ability to predict injury.
142: Arthroscopic and Magnetic Resonance Imaging (MRI) Grading of Articular
Cartilage Lesions of the Knee: Inter-rater Reliability and Reliability Between Modalities
Randy Mascarenhas, MB; Eric J Kropf, US; Charity G Moore, US; Joanna Costello, US;
Peter B MacDonald, MB; Constance R Chu, US; Christopher D Harner, US; James J Irrgang,
US
Purpose: The purpose of this study was to determine inter-rater agreement for identification
and grading of cartilage lesions in the knee by arthroscopy and magnetic resonance imaging
(MRI).
Method: De-identified videos and corresponding MRI from 21 patients were randomized and
shown to 4 surgeons and 3 radiologists. Videos and MRI were graded in a blinded manner.
Lesions were identified and graded for 9 regions on the femoral condyle and 5 regions on the
tibial plateau using the modified ICRS grading scale. Kendall’s coefficient of concordance
(Kendall’s W) was calculated to determine agreement amongst surgeons, amongst radiologists
and between surgeons and radiologists.
Results: Inter-rater agreement amongst surgeons was highest in the central-central zone on
the femoral condyle (W=.80) and the non-meniscus weight-bearing zone on the tibial plateau
(W=.64). Amongst radiologists, inter-rater agreement was highest for the central-central zone
on the femoral condyle (W=.67) and the anterior meniscus zone on the tibial plateau (W=.64).
The highest agreement between arthroscopic and MRI grading was found for the centralcentral zone on the femoral condyle (W=.66) and the non-meniscus weight bearing zone on
the tibial plateau (W=.49). In general, agreement between arthroscopic and MRI grading was
higher for the femoral condyle than for the tibial plateau.
Conclusion: Fair agreement was seen between arthroscopic and MRI grading of articular
cartilage lesions. Inter-rater agreement was highest for centrally located femoral and tibial
lesions and lowest for peripheral femoral lesions. Cartilage-sensitive MRI sequences may be
required for more accurate diagnosis and grading of articular cartilage lesions.
143: Correlation of WOMAC/KOOS Scores to Cartilage Loss on 3T MRI and Plane
Radiography: Data from the Osteoarthritis Initiative (A Prospective Multicenter Study)
Kenneth David Illingworth, US; Youssef El Bitar, US; Kyle Siewert, US; Steven Scaife, US;
Khaled Saleh, US
Purpose: Subjective patient scores have been used as measuring parameters for patient
function as well as outcome assessments after knee surgery. Two of the most common
subjective scores used are the Knee Injury Osteoarthritis Outcomes Score (KOOS) and the
Western Ontario and McMaster Universities Osteoarthritis Index Scores (WOMAC). The
purpose of this study was to determine the correlation between these subject scores and the
degree of cartilage loss on 3 Tesla MRI and plane radiography. Our hypothesis is that an
increase in cartilage loss will be associated with decreasing patient scores indicating greater
pain and dysfunction.
Method: Data used in the preparation of this article were obtained from the Osteoarthritis
Initiative (OAI) database (OAI public use data sets kMRI_QCart_Eckstein18 and
kXR_QJSW_Duryea16). Of the 906 patients at baseline with 3Tesla MRI, 497 patients were
identified that had documented WOMAC/KOOS scores, quantitative cartilage data on 3T MRI
and baseline posterior anterior flexion weight bearing plane radiographs. Each patient at
baseline took the KOOS function, sports and recreational activities score, KOOS Pain score,
KOOS quality of life score, KOOS symptom score, WOMAC disability score, WOMAC pain
score, WOMAC stiffness score and WOMAC total score questionnaires. Each subjective score
was correlated to the degree of cartilage loss on 3T MRI, as assessed by percentage of
tibiofemoral subchondral bone denuded of cartilage, and degree of joint space narrowing on
plane radiographs using Pearson correlation coefficients with a statistical significance of p <
0.05.
Results: The KOOS symptom score had a statistically significant correlation to subchondral
bone denuded of cartilage at all 10 areas of the tibia and all 6 areas of the femur with an
average correlation of r = -0.17, p < 0.05. The highest KOOS symptom score correlation was in
the external medial tibia (r = -0.25, p < 0.05) for the tibia and in the central medial femoral
condyle (r = -0.25, p < 0.05) for the femur. The only other score to have a significant correlation
greater than r = -0.20 was the KOOS pain score in the external medial tibia. No WOMAC score
had a correlation greater that r = -0.20. Similar findings were noted for the correlation of joint
space loss on plan radiography, with the KOOS symptom score having the highest correlation
(r = 0.20).
Conclusion: The highest significant correlation was found between the KOOS symptom score
and cartilage loss on 3 Tesla MRI and joint space width on plane radiographs, although the
correlations were weak in all areas. These patient subject scores have been heavily utilized as
tools for patient assessment of knee osteoarthritis, dysfunction and outcomes. However, these
scores only weakly correlate with the degree of cartilage loss in the tibiofemoral joint and
therefore further emphasize the fact that pain, dysfunction and OA is a multifactorial process.
144: Does Ligament Preservation During Anterior Cruciate Ligament (ACL)
Reconstructive Surgery in ACL Deficient Patients Improve Patient-reported Outcomes at
One-year? A Prospective Cohort Study
Nicholas GH Mohtadi, AB; Denise S Chan, AB; Rhamona S Humphrey, AB; Alexandra
Naylor, AB
Purpose: To prospectively compare the disease-specific quality of life and clinical outcomes of
patients who had ACL reconstructive surgery with ligament preservation using a hamstring
tendon autograft to patients who underwent a standard ACL reconstruction at one year.
Method: This prospective cohort study compared two groups of ACL deficient patients
undergoing ACL reconstruction. Group 1 (Preserved) had a preserved ACL and 2-stranded
semitendinosus autograft reconstruction (n=43; 19 males, 24 females; mean 30.1 years; 20
acute); Group 2 (Standard HT) had a standard 4-stranded semitendinosus and gracilis
autograft reconstruction (n=43; 24 males, 19 females; mean 30.3 years; 16 acute). The ACL
preservation technique was indicated and performed in ACL deficient patients with mild to
moderate translation and rotational abnormalities under anesthesia, and arthroscopic evidence
of robust ACL tissue. At the time of reconstruction, the 2-stranded semitendinosus graft was
placed around or through preserved ACL tissue. Group 2 were matched based on age, gender
and acuity. All patients had identical fixation and surgical technique. The primary outcome was
the disease-specific, patient-reported ACL Quality of Life (ACL-QOL). Secondary outcomes
included the subjective and objective IKDC scores, KT Arthrometer measurements and the
pivot shift. An independent trained research coordinator measured the clinical outcomes.
Results: Matching the patients for age, gender and acuity was effective and showed no
difference between groups. Baseline ACL-QOL, IKDC scores, pivot shift and KT arthrometer
measurements were not statistically different. Mean one-year ACL-QOL scores approached
statistical significance, with 80.4 (SD=17.2; 95% CI=74.9-85.8) for the Preserved and 72.7
(SD=21.2; 95% CI=66.2-79.3) for the Standard HT, p=0.076. However, accounting for baseline
scores revealed a statistically significant change in ACL-QOL and subjective IKDC scores from
baseline to one year between the groups (p=0.026 and p=0.029, respectively). At one year,
mean objective IKDC scores were statistically different: 84% (36/43) of the Preserved and 74%
(32/43) of the Standard HT group had Normal or Nearly Normal knees (p=0.048). The
proportion of patients with a positive pivot shift at one year was not different between groups
(p=0.245). The mean side to side difference on the KT arthrometer (30lbs) was significantly
more stable for the Preserved (2.0mm, SD=1.5mm; 95% CI=1.4-2.5mm) compared to the
Standard HT (2.8mm; SD=1.8mm; 95% CI=2.2-3.4mm), p=0.030.
Conclusion: ACL preservation using a 2-stranded hamstring autograft results in better quality
of life, improved objective stability (KT arthrometer) and overall IKDC score with a higher
percentage of normal and nearly normal knees at one year compared to standard 4-stranded
hamstring tendon reconstruction. The clinical relevance of this study suggests that in 10-15%
of ACL deficient patients, a double stranded semitendinosus ACL preservation technique
should be considered.
145: Long-term Follow-up of ACL Reconstruction: Insight into the Natural History of
Altered Biomechanics of the Knee Joint
Jeffrey RS Leiter, MB; Robert Gourlay, MB; Sheila McRae, MB; Nevin de Korompay, MB;
Peter B MacDonald, MB
Purpose: The goal of anterior cruciate ligament (ACL) reconstruction is to restore knee
stability and prevent onset of osteoarthritis(OA). Little is known of the long-term natural history
of a knee joint that has undergone ACL reconstruction. The purpose of our study is to
investigate long-term changes in the knee joint following ACL reconstruction with respect to
OA, joint space narrowing, knee laxity, activity level, strength and quality of life. Hypothesis:
There will be no differences in the incidence and severity of knee OA, joint space narrowing,
knee laxity, activity level, quality of life, and knee flexion and extension strength between an
ACL reconstructed knee and the contralateral non-reconstructed (control) limb of study
participants.
Method: Study Design: Retrospective Case Series. The surgical database of the senior author
(PM) was searched to identify patients that had a semitendinosus/gracilis (ST) graft ACL
reconstruction and were more than 12 years post operative. Patients were contacted via phone
or mail and invited to participate. Clinical evaluation involved radiographic analysis, IKDC, KT1000, Tegner Activity Scale, Lysholm Knee Score, ACL-QOL , and knee flexor/extensor
strength testing using the Biodex III dynamometer.
Results: Sixty-eight (43 males, 25 female) participants consented to the study. Average age
(SD) at time of surgery was 31.2 (±9.1) years. At a mean follow-up of 14.6 (1.9) years postoperative, 7% of participants had re-ruptured their ACL whereas 6% ruptured their contralateral
ACL. Reconstructed knees presented with increased arthritic changes than the contralateral
side (p=0.001). Medial meniscal surgery (repair or partial menisectomy) was a strong predictor
of OA. There was no clinically significant difference in KT-1000 scores between reconstructed
and non-reconstructed knees. Seventy-five percent of participants scored a normal or nearly
normal knee on the IKDC. The mean Lysholm score was 75.8% and Tegner Activity Level
scores decreased significantly (0.001) from the time of surgery. Knee extension strength was
greater in the non reconstructed knee at speeds of 60-(p=0.014) and 150-deg/s(p=.012). There
was no difference in knee flexion strength at any speed.
Conclusion: Reconstructed knees have increased OA changes compared to nonreconstructed knees and medial meniscal surgery is a strong predictor of OA. Despite this,
75% of patients reported good outcomes at greater than 12 year follow-up. This study provides
insight into the long-term natural history of ACL reconstuction which is imperative to develop
techniques and programs aimed at preventing, or delaying the onset of OA.
146: Managing Knee Osteoarthritis: The Effects of Body Weight Supported Activity on
Joint Pain and Physical Function
Mathew Christian, MB; Jason Peeler, MB; Jeffrey RS Leiter, MB; Peter B MacDonald, MB
Purpose: Knee osteoarthritis (OA) is a degenerative joint condition characterized by
progressive joint pain, swelling, and loss of muscle and joint function for which there is no
known cure. Current research indicates that the most important modifiable risk factor for the
development and progression of knee OA is obesity, a condition that is increasingly common in
older adults. Contemporary exercise programs aimed to initiate weight loss and improve knee
OA symptoms involve activities that increase joint loading, which is a risk factor for further joint
degradation and disease progression. Using a new anti-gravity treadmill, capable of generating
a lifting force using differential air pressure (DAP), patients with knee OA can engage in regular
physical activity while minimizing joint loading. The aim of this study was to assess the effect of
a 12-week, anti-gravity treadmill walking program on knee pain and function in obese older
adults with knee OA.
Method: Participants between ages 55-75, with a body mass index (BMI) ≥ 25 kg/m2, and
symptomatic knee OA were recruited. Data from a preliminary safety analysis is presented for
13 participants, with a mean (SD) age of 60.2 (5.6) years and BMI of 35.5 (7.7) kg/m2. Over a
12 week period, participants exercised twice weekly on an anti-gravity treadmill at a
percentage of body weight that minimized knee pain while walking. Knee symptoms and
function (Knee injury and Osteoarthritis Outcome Score (KOOS), knee pain during full weightbearing treadmill walking (FTW), cardiovascular fitness (YMCA submaximal cycle ergometer
test), and activity level (average daily pedometer readings) were assessed at baseline and
following the completion of the 12-week program using paired t-tests (α = 0.05).
Results: Improvements between baseline and outtake were found in all KOOS subscales
(Pain: p=0.023; Symptoms: p=0.001; Activities of Daily Living: p=0.045; Sport & Recreation:
p=0.050; Quality of Life: p=0.0002). Knee pain during FTW decreased (p=0.0048).
Cardiovascular fitness (p=0.011) and average daily pedometer readings (p=0.006) were also
increased.
Conclusion: Preliminary results of this study suggest that anti-gravity treadmill walking
improves knee pain and function during full weight bearing daily activities, including full weightbearing treadmill walking. Cardiovascular fitness and daily activity levels also improved. These
findings suggest that anti-gravity treadmill technology has the potential to improve the overall
health and functional autonomy of at-risk individuals, and advance current methods of
rehabilitation and long term management of chronic symptomatic knee OA.
147: Measuring the Anterior Cruciate Ligament’s Footprints by Three-dimensional
Magnetic Resonance Imaging
Adam Hart, QC; Yung Han, QC; David Kurzencwyg, QC; Tom Powell, QC; Paul A Martineau,
QC
Purpose: The purpose of this study was to compare three-dimensional magnetic resonance
(3D MR) imaging with open cadaveric measurements of the anterior cruciate ligament’s (ACL)
footprint in order to see whether the scanned images are accurate enough to be used for
preoperative templating in anatomic ACL reconstruction.
Method: Eight formalin-injected cadaveric knees were scanned by rapid acquisition isotropic
3D MR imaging. The femoral and tibial footprints were measured on MR imaging and
compared with cadaveric dissection. Bland–Altman plots were used to assess the level of
agreement.
Results: The anteromedial (AM) and posterolateral (PL) fibre bundles were clearly appreciated
in each specimen by 3D MR imaging and cadaveric dissection. The average paired difference
in the femoral and tibial footprint measurements was two, one, two, and two millimetres for the
femoral footprint length, femoral footprint width, tibial footprint length, and tibial footprint width,
respectively. The individual paired measurements were all within the mean difference ± two
standard deviations of the difference in the Bland–Altman plot showing strong agreement.
Conclusion: Measuring the ACL’s footprint by 3D MR imaging or open cadaveric dissection
has strong agreement and can be used interchangeably. Three-Dimensional MR imaging has
the potential to allow surgeons to: (1) tailor ACL reconstruction technique or graft choice based
on ACL footprint size, (2) plan for selective bundle ACL reconstruction for partial tears, and (3)
preoperatively template tunnel position according to the patient’s individual anatomy.
148: Meniscus Surgery and Cartilage Loss on 3T MRI: Data from the Osteoarthritis
Initiative (A Prospective Multicenter Study)
Kenneth David Illingworth, US; Matthew Lovell, US; Evan Armington, US; Steven Scaife,
US; Ryan Combs, US; Saadiq El-Amin, US; Khaled Saleh, US
Purpose: A history of previous meniscus injury or meniscectomy has been shown to be
associated with an increased incidence of knee osteoarthritis as hypothesized to be caused by
altered tibiofemoral knee kinematics with a shift in contact wear patterns. The purpose of this
study was to look at the effect of previous meniscus surgery on tibiofemoral joint cartilage wear
patterns as assessed by 3 Tesla magnetic resonance imaging. Our hypothesis is that
individuals with a history of meniscus surgery will have increased tibiofemoral osteoarthritis as
well as have specific wear patterns on the tibia and femur.
Method: Data used in the preparation of this article were obtained from the Osteoarthritis
Initiative (OAI) database (OAI public use data set kMRI_QCart_Eckstein18). Of the 906
patients at baseline with 3 Tesla magnetic resonance imaging and documented quantitative
cartilage data, 61 patients had a previous history of meniscus surgery and 667 control patients
had no history of meniscus surgery. All patients with a previous history of knee surgery, other
than meniscus surgery, were excluded. The percentage of subchondral bone denuded of
cartilage and minimum cartilage thickness in six femoral and ten tibial regions was quantified
for each patient. Each patient took the KOOS function, sports and recreational activities score,
KOOS Pain score, KOOS quality of life score, KOOS symptom score, WOMAC disability score,
WOMAC pain score, WOMAC stiffness score and WOMAC total score questionnaires.
Independent T-tests with a significance of p < 0.05 were used for group comparisons.
Results: There was a statistically significant increase in subchondral bone denuded of
cartilage in all tibial regions and in the medial femoral condyle in patients with a history of
meniscus surgery (p < 0.05). The largest mean differences between groups were found in the
external medial femoral condyle and central medial femoral condyle, and the external medial
tibia and posterior medial tibial regions. There was a statistically significant decrease in mean
cartilage thickness in the external medial tibia, internal lateral tibia, posterior lateral tibia,
external medial femoral condyle and central medial condyle in patients with a history of
meniscus surgery (p < 0.05). Patients with a history of meniscus surgery had a statistically
significant worse subjective KOOS and WOMAC scores in all areas when compared to no
history of meniscus surgery (p < 0.05).
Conclusion: Patients with a history of meniscus surgery have decreased cartilage in both the
medial and lateral tibiofemoral compartments as assessed on 3 Tesla MRI, with a more
pronounced decrease in cartilage being found in the medial compartment. Patients with a
history of meniscus surgery have increased pain and decreased function as shown with the
KOOS and WOMAC scores in this study.
149: Meniscus Surgery and Joint Space Width Narrowing on Plane Radiographs: Data
from the Osteoarthritis Initiative (A Prospective Multicenter Study)
Kenneth David Illingworth, US; Evan Armington, US; Matthew Lovell, US; Steven Scaife,
US; Ryan Combs, US; Saadiq El-Amin, US; Khaled Saleh, US
Purpose: A history of previous meniscus injury or meniscectomy has been shown to be
associated with an increased incidence of knee osteoarthritis due to alterations in knee
kinematics and contact wear patterns. The purpose of this study was to evaluate posterior to
anterior flexion weight bearing radiographs of patients with a previous history of meniscus
surgery in one knee and compare this with the contralateral knee with no previous surgery. Our
hypothesis is that the knee with the history of meniscus surgery will have more significant
quantifiable tibiofemoral joint space narrowing. Also the degree of joint space narrowing will be
correlated to how far out the individuals are from surgery.
Method: Data used in the preparation of this article were obtained from the Osteoarthritis
Initiative (OAI) public use data set (kXR_QJSW_Duryea16). Of the 1,805 patients with joint
space width quantified, 187 individuals had a positive history of previous meniscus surgery on
one knee with no history of surgery on their contralateral knee. All individuals had standing
flexion weight bearing posterior to anterior x-rays. Joint space width narrowing was analyzed at
16 locations in the tibiofemoral joint, with 7 locations in the medial compartment and 9
locations in the lateral compartment. Time from surgery was recorded for each individual.
Independent T-tests were used for comparison between individual’s knees.
Results: Mean time from surgery for the 187 individuals was 12.99 +/- 13.5 years. The mean
decrease in medial and lateral joint space in knees with previous meniscus surgery compared
to no history of meniscus surgery was 0.94 mm and 0.48 mm, respectively. There was a
statistically significant decrease in joint space width in all 7 measurements of the medial
compartment in the meniscus knee group (p < 0.001). There was also a statistically significant
decrease in joint space width in the most medial measurement of the lateral compartment in
the meniscus knee group (p < 0.001), with no statistically significant difference being found
between the remainder of the lateral joint space measurements between knees.
Conclusion: Patients with a history of meniscus surgery are more like to have a decrease in
tibiofemoral joint space width on posterior to anterior x-rays, with a larger decrease being
found in the medial compartment.
150: Poor Agreement Amongst Surgeons Arthroscopically Evaluating Anterior Cruciate
Ligament Tunnel Placement
Mark O McConkey, BC; Annuziato Amendola, US; MOON Group, US; Brian R Wolf, US
Purpose: To evaluate the agreement on ACL tunnel position between performing surgeon and
independent evaluating surgeons using arthroscopic assessment. Our hypothesis is that the
performing and evaluating surgeons would characterize the tunnel positions significantly
differently.
Method: Twelve experienced knee surgeons performed six ACL reconstructions each on a
total of 72 cadavers. Four surgeons each performed trans-tibial (TT), medial portal (MP), and
two-incision techniques (2I) for femoral drilling. They drilled tibial and femoral tunnels using
their standard technique. Subsequently, they completed a form to document their assessment
of tibial and femoral tunnel placement. Back wall thickness was judged ideal, too thick or too
thin. Femoral tunnel position was estimated using clock-face technique and overall position
was deemed ideal, too vertical, too horizontal, too anterior or too posterior. Tibial tunnel
apertures were judged ideal, too anterior, too posterior, too medial or too lateral. Femoral and
tibial tunnels were then noted to be acceptable or unacceptable. Three independent surgeon
reviewers examined each knee and filled out the same form documenting tunnel position.
Statistics were performed to compare tunnel position judgment of performing and evaluating
surgeons and tunnel placement was compared to surgical technique. Agreement between
surgeons was analyzed with Kappa values.
Results: Differences between surgeon and independent evaluations were found to be
significant. The surgeon would more likely judge his femoral tunnel position (92.65% vs
70.00%; p=0.0054) and wall thickness (93.94% vs 74.24%; p=0.0004) ideal compared to an
observer. Surgeons also judged tunnels acceptable significantly more often (98.48% vs
82.32%; p=0.0009). Observers’ assessments of femoral tunnel position were analyzed based
on surgical technique. Tunnels were more likely to be judged ideal when 2I technique was
used compared to MP and TT (86.96% vs 66.67% vs 51.67%; p<0.0001). Tibial tunnel
positions had similar findings with the surgeon more likely to deem his tunnel ideal (95.59% vs
58.10%; p<0.0001); observers judged the tunnels too posterior in 29.52% of cases. When
asked if tunnels were acceptable or unacceptable surgeons and observers differed (100% vs
89.89% acceptable; p=0.0052). Tunnel positions differed significantly based on technique
again: MP 68.12%, 2I 62.32%, and TT 38.33% were ideal (p=0.0002). When TT technique was
used 53.33% of tunnels were judged too posterior.Agreement amongst surgeons and
observers was overall poor for each parameter with Kappa values ranging from -0.0053 to
0.2457.
Conclusion: Surgeons are more likely to judge tunnels they drilled ideal and acceptable than
observers. TT technique yields more poorly positioned tunnels than 2I or MP techniques when
judged arthroscopically. Overall agreement on tunnel position was poor amongst the surgeons
especially for clock-face technique. Surgeons do not agree on the ideal placement for single
bundle ACL tunnels.
151: Clinical Outcomes of Fractures of the Distal Radius in Men Under the Age of 50
Geoffrey Johnston SK
Purpose: To document the process of clinical recovery and treatment outcomes of distal radial
fractures in men under the age of 50.
Method: The outcome measures included the patient rated wrist evaluation (PRWE), and the
percentage of active dorsiflexion, palmarflexion, supination, pronation, and grip strength (GS)
compared to the uninjured opposite arm. These were assessed at nine weeks, three, six and
12 months post-fracture. Data for dominant and non-dominant limbs were pooled.
Results: Ninety-five men 20 - 49 years old were evaluated, for up to one year after their distal
radial fracture. Of these 95 fractures 50 (53%) involved the non-dominant, and 45 (47%) the
dominant arm. Fifty-three patients were treated non-operatively, 42 operatively.The mean x-ray
values in the non-operative and operative groups, respectively, at 3 months were: radial
inclination of 23 degrees and 25 degrees, positive ulnar variance of 1.5 in both, and dorsal tilt
of 1 degree and volar tilt of 2 degrees, In the non-operative group at 9 weeks post-fracture 27
(51%) completed the PRWE, 19 (45%) from the operative group. Mean PRWE scores were 46
for the non-operative group and 65 for the operative group. Mean DF, PF, supination and
pronation values were 79%, 73%, 81% and 91%, and 58%, 63%, 75% and 93% for the non-
operative and operative groups, respectively. GS averaged 47% and 38% for the nonoperative and operative sides, respectively. In the non-operative group at 3 months postfracture 25 (47%) completed the PRWE, and 19 (45%) from the operative group. Mean PRWE
scores were 35 for the non-operative group and 46 for the operative group. Mean DF, PF,
supination and pronation values were 85%, 79%, 81% and 95%, and 67%, 65%, 83% and
95% respectively for the non-operative and operative groups, respectively. GS averaged 57%
and 48% for the non-operative and operative sides, respectively. In the non-operative group at
6 months post-fracture 12 (23%) completed the PRWE, and 13 (31%) from the operative
group. Mean PRWE scores were 17 for the non-operative group and 37 for the operative
group. Mean DF, PF, supination and pronation values were 97%, 87%, 90% and 97%, and
80%, 80%, 97% and 95% for the non-operative and operative groups, respectively. GS
averaged 70% and 69% for the non-operative and operative sides, respectively. In the nonoperative group at 12 months post-fracture 4 (8%) completed the PRWE, and 10 (24%) from
the operative group. Mean PRWE scores were 5 for the non-operative group and 27 for the
operative group. Mean DF, PF, supination and pronation values were 100%, 78%, 91% and
97%, and 83%, 77%, 90% and 98% for the non-operative and operative groups, respectively.
GS averaged 87% and 78% for the non-operative and operative sides, respectively.
Conclusion: Although motion was restored early, recovery from a distal radial fracture in this
young population, as reported by the patient and by grip strength, may take at least a year to
rival the uninjured side.
152: Effects of Regional Anaesthesia (RA) versus General Anaesthesia (GA) on
Outcomes of Distal Radius Open Reduction and Internal Fixation (ORIF)
Henry Broekhuyse, BC; Sebastian Jonathan Ko, BC; Calvin Wang, BC; Robert Petretta, BC
Purpose: The purpose of this study was to determine what effect the type of anaesthesia
might have on early clinical and functional outcomes following ORIF of distal radius fractures.
Method: We performed a retrospective review of patient data obtained from a prospectively
collected database of patients treated for distal radius fractures at a Level 1 Trauma centre. A
total of 503 distal radius fractures were treated surgically from November 2004 to February
2011. Inclusion criteria were (1) distal radius fracture treated with ORIF; (2) received GA alone,
RA alone, or RA + GA; (3) at least 1 year of post-surgical followup. Exclusion criteria were (1)
patients treated with external fixation or percutaneous pinning; (2) presence of other ipsilateral
upper extremity injuries, (3) other significant injuries requiring operative intervention. A total of
445 patients were included, 263 pts (n=263) in group 1 (GA), and 182 pts (n=182) in group 2
(RA +/- GA). At 3, 6 and 12 months post-op, patients were evaluated (1) objectively by the
physiotherapists on ROM, grip and pinch strength, and (2) subjectively by the DASH, PRWE,
and SF-36 functional outcome questionnaires.
Results: There was no difference in patient demographics between the groups, except for a
statistically significant increased anaesthesia time (p<0.000001) for the RA group (34 mins)
compared to the GA group (28 mins), and a higher baseline SF-36 physical component
summary score (p=0.029). At 3 months, the GA group demonstrated better wrist flexion
(compared to the contralateral non-injured side) by 7% (p=0.031), grip strength by 12%
(p=0.017), and pinch strength by 12% (p=0.022). The RA group had improved wrist extension
at 6 months, although this was not statistically significant. At 12 months, wrist supination was
improved by 3.1% in the RA group (p=0.049). No difference was found in grip or pinch strength
at 6 and 12 months. With regards to functional outcome scores, the RA group tended to have
better DASH scores at 3, 6, and 12 months, but this was not statistically significant. At 3
months, there was no difference in PRWE scores between the two groups. At 6 months, the
RA group had statistically significant lower disability on the PRWE pain subscore (p=0.052)
and total score (p=0.055). The RA group tended to have better PRWE subscores at 12
months, but this was not statistically significant. There was no difference in SF-36 scores
between the two groups at any time interval.
Conclusion: This study suggests that patients receiving general anaesthesia have improved
wrist motion and strength at 3 months, when compared with patients receiving regional
anaesthesia. Patients receiving regional anaesthesia may have improved functional outcomes
compared with patients receiving general anaesthesia, although this was not statistically
significant at all time intervals. Effects of the choice of anaesthesia on both clinical and
functional patient outcomes appear to be diminished with longer follow-up intervals.
153: External Fixation versus Open Reduction with Plate Fixation for Distal Radius
Fractures: A Meta-analysis of Randomized Controlled Trials
Paul RT Kuzyk, ON; John Esposito, AB; Michel Saccone, ON; Emil H Schemitsch, ON
Purpose: Both external fixation and open reduction with internal fixation (ORIF) using plates
have been recommended for treatment of distal radius fractures. We conducted a systematic
review and meta-analysis of randomized controlled trials comparing external fixation to ORIF
with plate fixation.
Method: MEDLINE, EMBASE, and COCHRANE databases were searched from inception to
January 2011 for all trials involving use of ORIF with plate fixation and external fixation for
distal radius fractures. Eligibility for inclusion in the review was: use of random allocation of
treatments; treatment arm receiving external fixation; and treatment arm receiving ORIF with
plate fixation. Eligible studies were obtained and read in full by two co-authors who then
independently applied the Checklist to Evaluate a Report of a Nonpharmacological Trial.
Pooled mean differences were calculated for the following continuous outcomes: wrist range of
motion; radiographic parameters; grip strength; and Disabilities of the Arm, Shoulder, and
Hand (DASH) score. Pooled risk ratios were calculated for rates of complications and
reoperation.
Results: The literature search strategy identified 52 potential publications of which nine
publications (10 studies) met inclusion criteria. The pooled mean difference for DASH scores
was significantly less for the ORIF with plate fixation group (-5.92, 95% C.I. of -9.89 to -1.96,
p<0.01, I2=39%). The pooled mean difference for ulnar variance was significantly less in the
ORIF with plate fixation group (-0.70, 95% C.I. of -1.20 to -0.19, P=0.006, I2=0%), indicating
better restoration of radial length for this group. The pooled risk ratio for infection was 0.37
(95% C.I. of 0.19 to 0.73, P=0.004, I2=0%), favouring ORIF with plate fixation. There were no
significant differences in all other clinical outcomes. Pooled data for most outcomes was
improved by including data from the four studies using volar plates exclusively.
Conclusion: ORIF with plate fixation provides lower DASH scores, better restoration of radial
length and reduced infection rates as compared to external fixation for treatment of distal
radius fractures.
154: Fractures of the Distal Radius in Women in Middle and Older Adulthood: The CAST
Trial - Preliminary Results of a Randomised Pilot Study
Charlene Magnus, SK; Geoffrey Johnston, SK; Catherine Arnold, SK; Vanina Dal Bello-Haas,
SK; Jenny Basran, SK; Joel Krentz, SK; Jonathan Farthing, SK
Purpose: The purpose was to apply cross-education (Contralateral Arm Strength Training CAST) during recovery from unilateral distal radial fractures in women in middle and older
adulthood and to evaluate its effects on muscle strength, range of motion and patients' selfreported wrist evaluations.
Method: Eighteen women were randomised to either a normal rehabilitation group (NORM), or
a normal rehabilitation plus strength training group (NORM+TRAIN). Normal rehabilitation
consisted of forearm casting for 40.8(SD6.2) days, and arm and finger exercises for the injured
extremity as prescribed by the orthopedic surgeon. The normal rehabilitation plus strength
training group did not only the same injured limb exercises but also performed hand strength
training on the uninjured side, completed at home three times/week with five sets of eight
repetitions using a handgrip trainer. Strength training of the uninjured hand began immediately
after the first visit to the orthopedic surgeon (week one). Peak force via a handgrip
dynamometer and range of motion (flexion/extension; supination/pronation) via a goniometer
were measured at week one on the uninjured side, and at weeks nine and 12 post-fracture on
both the fractured and non-fractured sides. Patients completed the Patient Rated Wrist
Evaluation (PRWE) at weeks nine and 12 post-fracture.
Results: The mean age of the women recruited was 63.2 years (SD:10.3). The uninjured hand
in the NORM+TRAIN group increased strength from week one [25.5(SD6.8)] to week nine
[27.7(SD7.8)], and week one to week 12 [28.3(SD8.0)] - p<0.05. No significant differences
were found in the uninjured hand of the NORM group. For the hand on the side of the fracture,
percent change at weeks nine and 12 was used to normalize strength to the uninjured hand at
week one. Results showed NORM+TRAIN had less of a deficit in strength [-40.8%(SD21.4)] at
12-weeks post fracture compared to NORM [-65.1%(SD21.7)] - p<0.05. There were no
significant differences in strength at week nine between groups, although there was less of a
deficit for NORM+TRAIN [-59.7%(SD23.7)] compared to NORM [-72.2%(SD20.5)]. For range
of motion at 12-weeks post fracture NORM+TRAIN had significantly improved wrist flexion
[45°(SD9.8)], and extension [52°(SD12.3)] compared to NORM [33.5°(SD11.5)] [34°(SD19.9)],
respectively - p<0.05. No other significant differences for range of motion were found. No
significant differences were identified in PRWE scores between the two groups at both weeks
nine and 12.
Conclusion: Strength training of the uninjured limb during the early care of a distal radius
fracture improved the strength and range of motion of the fractured limb 12 weeks after the
fracture, over that achieved by conventional treatment. These results have important
implications for rehabilitation strategies following distal radius fractures.
155: Prognostic Factors for Reoperation Following Plate Fixation of Fractures of the
Midshaft Clavicle
Emil H Schemitsch, ON; Laura A Schemitsch, ON; Lynn Vicente, ON; Paul Kuzyk, ON;
Michael D McKee, ON
Purpose: Plate fixation of midshaft fractures of the clavicle has become an accepted treatment
technique for completely displaced injuries. However, little information is available regarding
reoperation, a frequent concern. We conducted a retrospective review to determine which
prognostic factors were associated with reoperation following plate fixation of completely
displaced mid-shaft fractures.
Method: We identified 235 consecutive patients who underwent plate fixation for a midshaft
clavicle fracture at a single university-affiliated Level One trauma center between July 1, 2000
and July 1, 2009. We examined for 21 possible prognostic variables using multivariate logistic
regression analysis and documented reoperation rates.
Results: Two hundred and thirty five patients were identified. Eighty-two patients had less than
two year follow-up and were excluded from the study: none of these patients had had any
further surgery at the time of last follow-up. One hundred and fifty three patients were
contacted and assessed (65% of the total cohort). Fifty-eight of these patients had had
reoperations (38%), with eight of these individuals requiring multiple procedures (5%). The
majority of individuals had reoperation for plate removal (50/153, 33%), while the others were
for nonunion, hardware failure, refracture, or infection (8/153, 5%). Plate removal was
associated with the use of straight, non-contoured plates, and height <175 centimeters
(p<0.01). Risk factors for multiple reoperations (i.e. for infection, nonunion, fixation failure etc),
included substance abuse (illicit drugs or alcohol), diabetes, and age >55 years (p<0.01). This
information can be used prognostically: for example, use of a contoured plate in a person >175
cm tall results in a plate removal rate of only 9%. Conversely, substance abuse increases the
risk of requiring multiple reoperations from 3% to 25%.
Conclusion: We have presented the largest series to date that defines the rate of, and risk
factors associated with, reoperation following plate fixation of displaced midshaft fractures of
the clavicle. Our assessment of 153 patients provides some useful clinical information for
treatment and prognosis. Plate fixation of the clavicle is a safe, reliable operation with a low
major complication rate (5%). The rate of plate removal is significant (33%), and associated
with the use of straight plates: precontoured plates decrease this rate. Shorter (smaller)
patients had an increased rate of plate removal and can be counseled accordingly. Patients
with substance abuse issues, diabetes, or age >55 years had a significantly higher need for
multiple reoperations due to serious complications such as fixation failure or infection. Given
the relatively narrow risk-benefit profile of clavicle fracture fixation, extreme caution should be
used in recommending primary operative repair in these individuals.
156: The Impact of Region Wide Interventions Aimed at Improving the Timing of Hip
Fracture Surgery on Wait for Surgery, In-Hospital Mortality and Length of Stay
Eric R Bohm, MB; Lynda Loucks, MB; Ili Slobodian, MB; Luis Oppenheimer, MB
Purpose: The timing of hip fracture repair has been shown in retrospective analysis to have an
impact on mortality, with delays longer than 24-48 hours resulting in increased risk of death.
However, these findings need to be confirmed in an adequately powered prospective study. In
2005, Canada’s health ministers agreed to prioritize efforts aimed at completing hip fracture
surgery within 48 hours of admission. The CIHI Health Indicators report found that our region
had one of the longest waits for hip fracture surgery in Canada in 2005. This prompted
coordinated efforts to improve the timeliness of surgery at the five hospital sites in our region.
The purpose of this study was to prospectively evaluate the effectiveness of these efforts on
time to surgery, in-hospital mortality, and length of stay.
Method: The region-wide interventions to reduce delays to hip fracture surgery included;
implementation of standardized tracking procedures, identification of common reasons for
inappropriate delay, provision of educational sessions, modification of emergency OR booking
rules, and direct written communication with sites, surgeons and anesthetists. Data on time to
surgery and length of stay was collected using the Discharge Abstracting Database (DAD) and
the National Rehabilitation System (NRS), while mortality data was collected from both the
DAD and the provincial health database. Data consisted of 5213 admissions for hip fracture in
patients 50 years or older, grouped into three time periods: Before Intervention (1 Jan 2004 to
31 Dec 2007), During Intervention (1 Jan 2008 to 31 Dec 2008) and After Intervention (1 Jan
2009 to 30 June 2011).
Results: The mean patient age was 81.4 years, with 72.1% of patients being female; there
were no statistical differences in patient demographics by study period. The mean time to
surgery decreased from 3.4 days Before intervention, to 2.6 days During the intervention
period, to 1.8 days After the intervention period (p<0.0001). Length of stay decreased from
30.0 days Before to 23.9 days After the intervention period (p<0.0001). The overall in-hospital
mortality appeared to remain consistent at 6.4% Before, and 6.0% After the intervention
period, a difference of 0.4% (95%CI -1.7 to +1.0, p=0.53).
Conclusion: It appears that coordinated, region-wide interventions aimed at reducing time to
hip fracture repair can result in significant improvements in wait time to surgery and length of
stay. However we could not detect any impact on overall in-hospital mortality. Further analysis
is required to determine if there are differences in mortality risk by age group, or with longer
follow-up.
157: Surgical Fixation of Vancouver Type B1 Periprosthetic Femur Fractures - A
Systematic Review
Niloofar Dehghan, ON; Bill Ristevs.ki, ON; Michael D McKee, ON; Emil H Schemitsch, ON
Purpose: Periprosthetic fractures are a devastating complication of total hip arthroplasty. Type
B1 periprosthetic fractures occur at the tip of a stable implant, and may be treated with open
reduction and internal fixation (ORIF). However many different fixation techniques have been
described with no consensus on the best technique. Current treatment strategies include use
of cortical strut allografts alone, cable-plates or compression plates with/without cortical strut
allografts, and locking plates. This systematic review of literature investigates the outcomes of
these different treatment strategies.
Method: A literature review was conducted focusing on surgical fixation of type B1
periprosthetic fractures. Two independent reviewers reviewed the potential studies, and 19
studies were included for final analysis. These were all retrospective case series, with no
randomized control studies or prospective cohort trials. Studies were analyzed and categorized
depending on the method of fixation: 1) ORIF with strut allografts alone, 2) ORIF with cableplate/compression plates, 3) ORIF with cable-plate/compression plate and cortical strut
allograft, 4) ORIF with locking plates. Data analysis was performed comparing rates of union,
non-union, malunion, hardware failure, infection, re-operation, and total complications.
Results: Nineteen studies were identified with a total of 280 patients at final analysis. The rate
of total complications for all patients (N=280) was 34%: with 5% non-union, 6% malunion >5°,
5% hardware failure, 5% infection, and 12% re-operation. These varied between the four
different treatment groups. Cortical struts allografts alone were used in 26 patients, cableplate/compression plates were used in 149 cases, cable-plate/compression plates with cortical
strut allografts were used in 42 cases, and locking plates were used in 63 cases. Cortical strut
allografts alone vs. locking plates had significantly lower rates of total complications (19% vs
48%, P=0.02), but trended towards higher rate of malunion (12% vs 2%, P=0.08). Cableplate/compression plates vs. locking plates had significantly lower rate of hardware failure (3%
vs 14%, P=0.007), and total complications (32% vs 48%, P=0.02), with a trend towards lower
rate of non-union (4% vs 11%, P=0.06). Cable-plate/compression plates with cortical strut
allografts vs. locking plates had significantly lower rate of total complications (29% vs 48%,
P=0.04), and trended towards lower rates of hardware failure (2% vs 14%, P=0.07).
Conclusion: This systematic review suggests that with regards to fixation of type B1
periprosthetic femur fractures, locking plates have significantly higher rates of total
complications compared to the other three fixation options, and significantly higher rate of
hardware failure compared to cable-plate/compression plates. There are limitations to this
study, and further investigation with high quality randomized control trials is needed to further
assess these outcomes.
158: Systematic Follow-up of Osteoporotic Fracture: Preliminary Results of a
Multidisciplinary Approach
Josee Delisle, QC; Julio Fernandes, QC; Yves Troyanov, QC; Pierre Beaumont, QC; Benoit
Benoit, QC; Sylvain Gagnon, QC; Alain Jodoin, QC; G Yves Laflamme, QC; Stephane Leduc,
QC; Jean-Marc Mac-thiong, QC; Michel Malo, QC; Gilles Maurais, QC; Stefan Parent, QC;
Pierre Ranger, QC; Sylvie Perreault, QC
Purpose: Only 12% of the fractures that we treat each year receive a treatment for
osteoporosis in our orthopaedic surgery department. The 2010 clinical guidelines of
Osteoporosis Canada for the diagnosis of osteoporosis, indicates that patients that have
sustained a fragility fracture have a higher risk of sustaining a subsequent fracture. We are
validating a multidisciplinary systematic follow-up approach for osteoporosis and patients are
managed by a clinical nurse specialist. We aim to evaluate the impact of a multidisciplinary
approach on the incidence of a subsequent fragility fracture, on initiation of a treatment
(evaluation of compliance and adherence to treatment) and treatment efficacy (bone markers).
We will also evaluate the functional outcome and quality of life post-fracture.
Method: We are recruiting 543 patients (men and women) over 40 years of age who were
treated for a fragility fracture at the orthopaedic clinic of Hôpital du Sacré-Cœur de Montréal.
After starting a treatment protocol for osteoporosis, we evaluate the compliance and
adherence to treatment, bone markers (CTX-1 and Osteocalcin) and the subjects fill up
functional outcome questionnaires at different time intervals over a 24 months period.
Results: Two hundred thirty-five patients (28 men and 207 women) were enrolled with a mean
age of 62.0 y.o (+ 12.9) and a mean FU of 4.5 months (+ 3.5). Fifteen patients (6.4%) dropped
out after six months. One of them died. Three patients were excluded (1.3%). Mean patient’s
age was 64.4 y.o (+ 12.9) with a mean FU of 4.6 months (+ 3.9). Fifty-five patients (23.4%)
were already on bisphosphonates and 92 pts (39.1 %) had already sustained a fragility
fracture. All patients were prescribed risedronate except eight that were prescribed zoledronic
acid for intolerance or contraindication to oral bisphosphonates. Ten patients qualified for
teriparatide and two patients accepted to start the treatment. SF-12 was statistically higher (p<
0.000) at last follow up than baseline (PCS: 42.5 vs 37.7 and MCS: 49.3 vs 47.4; respectively).
Up to now, we obtained 91.9% persistence. After validation, 15% of the patients needed to be
referred to a rheumatologist and 85% of the patients were managed by the clinical nurse
specialist.
Conclusion: In our orthopaedic surgery department, the osteoporosis treatment rate went
from 12 to 64.8 % after implementation of our multidisciplinary systematic follow up of fragility
fractures. The 91.9% persistence rate in the first year compares favorably with the 50-75% rate
cited in the literature. Management of the underlying osteoporosis that leads to fragility
fractures could be done by Clinical Nurse Specialists. We believe this program is a plus value
to orthopedic surgery because it provides a fracture registry as well as a functional outcome
database for all fracture patients.
159: Systematic Review of the Treatment of Periprosthetic Distal Femur Fractures
Bill Ristevski, ON; Aaron Nauth, ON; Dale Williams, ON; Jeremy Hall, ON; Daniel Whelan,
ON; Mohit Bhandari, ON; Emil H Schemitsch, ON
Purpose: To systematically review and compare non-operative and operative treatments for
the management of periprosthetic distal femur fractures adjacent to total knee arthroplasties.
Specific operative interventions compared included locked plating, retrograde intramedullary
nailing (RIMN), and conventional (non-locked) fixation.
Method: A comprehensive database search (via Pubmed, Medline, Cochrane Database, OTA
and AAOS Databases) was completed, yielding 44 eligible studies with a total of 719 fractures
for analysis. Pertinent outcomes including nonunion, malunion and the need for secondary
surgical procedures were compared statistically.
Results: Both locked plating and RIMN showed significant advantages over non-operative
treatment. Locked plating also had a significantly lower malunion rate when compared with
RIMN and conventional fixation. A subset analysis comparing surgical treatments is shown in
the table below.
Nonunion...............Malunion................SSP...........
Conventional vs
Locked Plating.......9.2% vs 8.8%........19.2% vs 7.6%......16.7% vs 13.3%
OR (95% CI)..........1.05 (0.55-2.02)......2.87 (1.53-5.38).....1.30 (0.78-2.18)
p value..................0.87......................0.001*...................0.32
Conventional vs
RIMN....................9.2% vs 3.6%........19.2% vs 16.4%....16.7% vs 9.1%
OR (95% CI)..........2.68 (0.87-8.25).....1.21 (0.64-2.29)......2.00 (0.93-4.29)
p value..................0.08......................0.55......................0.07
RIMN vs
Locked Plating......3.6% vs 8.7%........16.4% vs 7.6%.......9.1% vs 13.3%
OR (95% CI).........0.39 (0.13-1.15)......2.37 (1.17-4.81)......0.65 (0.31-1.35)
p value.................0.09.......................0.02*.....................0.25
Conventional = Non-locked fixation; RIMN = Retrograde intramedullary nailing; OR = Odds
Ratio; CI = Confidence Interval; SSP = Secondary surgical procedure; * denotes significant p
value
Conclusion: Locked plating and RIMN offer significant advantages over non-operative
treatment and conventional (non-locked) fixation techniques in the management of
periprosthetic femur fractures above total knee arthroplasties. When locked plating was
compared to RIMN, there were no statistically significant differences in the rates of nonunion
and revision surgery. However, this review demonstrated that the rate of malunion was
significantly higher with RIMN compared to locked plating (OR=2.37,95% CI=1.17-4.81,
p=0.02). These results suggest that locked plating may offer superior outcomes in the
management of periprosthetic fractures of the femur following total knee arthroplasty.
160: The Temporal Pattern of Radiographic Loss of Reduction in Closed Management of
Distal Radial Fractures in 221 Women 50 years and Older
Presenter: Geoffrey Johnston
Purpose: To document the temporal pattern of change of three radiographic parameters
during non-operative treatment of distal radial fractures in women 50 years and older
Method: The radiographic parameters of radial inclination (RI), ulnar variance (UV) and tilt
were measured after closed reduction of a fracture of the distal radius in a population of
women 50 years and older, and who were treated non-operatively. The same parameters were
measured at weeks one, two, three, six, nine and twelve in these women. The women were
assigned to two groups, those in whom the dominant arm was involved, the other, those in
whom the non-dominant arm was fractured.
Results: Two hundred and twenty-one women 50 years and older who were treated by closed
reduction and non-operative management of a displaced distal radial fracture were evaluated.
One hundred and one (101) were of the dominant extremity, and 120 were of the nondominant extremity. Not all women had x-rays at each of the time periods. The averages for
each time period were calculated. The mean post-reduction values in the dominant and nondominant injured arms for radial inclination were 20 degrees and 22 degrees, and at week one,
19 degrees and 20 degrees, and 18 degrees and 19 degrees at two, three, six, nine and
twelve weeks, respectively. The mean post-reduction values in the dominant and nondominant injured arms for ulnar variance were 1.4 mm and 1.3 mm, and at week one, 2.0 mm
in both, at week two 2.1 in both, at week three 2.5 mm and 2.8 mm, at week six 3.6 mm and
3.3 mm, at week nine 3.3 and 3.1 mm, and at twelve weeks 3.4 and 3.1 mm, respectively. The
mean post-reduction values in the dominant and non-dominant injured arms for tilt were -4
degrees and -5 degrees (a minus value denotes volar tilt, a positive value dorsal tilt), and at
week one -1 degrees and -2 degrees, at week two 0 degrees and -1 degrees, at week three 3
degrees and 1 degrees, at week six 5 degrees and 2 degrees, at week nine 2 degrees and 1
degrees, and at twelve weeks 4 degrees and 2 degrees, respectively.
Conclusion: In general, radial sided fracture settling, reflected by diminishing radial inclination
appears to stabilize by week two post fracture. In contrast, axial radial shortening and dorsal
fracture collapse, reflected by increasing ulnar variance and dorsal tilt, respectively, appear to
stabilize later, between three and six weeks post-fracture.
161: Adamantinoma of Bone
Courtney Erin Sherman, US; Eduardo N Novais, US; Doris Wenger, US; Peter Rose, US;
Franklin Sim, US
Purpose: The purpose of this study is to investigate the clinical presentation and oncological
outcomes of patients with adamantinoma treated surgically in a single institution.
Method: Forty patients with a histologic confirmed classic adamantinoma were treated in our
institution between 1939 and 1999. The medical clinical records, radiographs, advanced
imaging, histologic and operative reports of these patients were retrospectively reviewed.
Institutional Review Board approval was obtained. Demographic data, presenting symptoms
and clinical findings on physical examination were recorded. Data about the treatment modality
were obtained. Histologic analysis confirmed the diagnosis in all cases according to previously
established criteria. Follow-up data included clinical and radiographic information focusing on
complications, local recurrence, metastasis and overall survival after treatment and its
management. All patients were followed for at least two years and the mean duration of followup was 12.8 years (range, 12-469 months).
Results: We reviewed 40 cases of adamantinoma of long bones. Twenty-eight occurred in the
tibia, six in the tibia and fibula, one in the femur, two in the ulna, one in the fibula, one in the
humerus, and one in the radius. Most patients presented with pain and swelling. The mean
age was 13 years (seven-79 years). Thirty four patients were treated initially with a limb
sparing surgery and eight with an amputation. The survival rate of the entire series was 78.6%
with a mean follow-up of 13 years. Eight (20%) patients had recurrent local disease, nine
(22.5%) developed lung and/or lymph node metastasis. Nine patients died of their disease at
mean follow up of 10 years (nine months to 21 years) and most of them were initially treated
with an amputation (p=0.04). No statistical differences were observed in others risk factors for
recurrent or metastatic disease.
Conclusion: Our results indicate that amputation doesn’t improve the survival rate of this
group of patients, wide en bloc resection is the treatment of choice. All patients require longterm follow-up for evidence of local recurrence or metastasis.
162: Bone Metastases from Renal Cell Carcinoma – En-bloc or Intralesional Resection?
Benjamin Deheshi, ON; Antonella Racano, ON; Osama Al-Shaya, ON; Emad Al-Absi, ON;
Michelle Ghert, ON
Purpose: Bone metastases from renal cell carcinoma (RCC) are highly resistant to radiation
and chemotherapy and must often be treated surgically to avert pathological fracture.
However, surgical management remains controversial and must be tailored to an individual’s
prognosis and functional status. The objective of this study was to determine the oncologic
outcome of en-bloc resection vs. intralesional curettage vs. intramedullary nailing (IMN) of
bone metastases from RCC.
Method: A prospectively collected database of 50 bone metastases from RCC (involving the
pelvis and the extremities) in 41 patients treated at the Juravinski Cancer Center in Hamilton,
Ontario, Canada, between 1996 and 2010, was reviewed. Patients with a minimum follow-up
of 12 months, or less than 12 months survival were included. Available data included:
demographics, site, type of surgery, pattern and timing of metastasis, local recurrence or
progression, and survival time.
Results: A total of 31 patients with 43 lesions were included in the review. Fourteen patients
(42%) had visceral metastases at presentation, while 17 patients (58%) presented with bone
metastases only. The initial procedure was en-bloc resection in 13 patients (42%), intralesional
curettage in nine patients (29%), and IMN in nine patients (29%). Two lesions (13%) treated by
en-bloc resection recurred locally, while four lesions (14%) in the curettage/IMN groups
progressed locally; one case of local progression from each treatment group required further
surgery. The average survival was 30.5 months following en-bloc resection and 17 months
following curettage/IMN.
Conclusion: The results reaffirm that patients with RCC metastases to bone can have
prolonged survival. Interestingly, there was no significant difference in local tumor recurrence
or progression between en-bloc and intralesional groups. Overall survival time appears to be
better following en-bloc resection in patients with isolated bone metastases; however this may
be due to a selection bias. Patients who presented with visceral metastases, show no marked
differences in survival times between en-bloc and intralesional groups. Future studies would
include the impact of primary tumor biology, sensitivity to adjuvant treatment, and surgical
approach on functional outcome and survival in a prospective multi-center trial.
163: Effect of Chemotherapy and Cement Fixation on Tumour Endoprosthesis Survival
Bas A Masri, BC; Luke Pugh, BC; Paul W Clarkson, BC
Purpose: To determine the effects of chemotherapy and cemented or uncemented fixation
techniques on tumor endoprosthesis survival at our center.
Method: We performed a retrospective cohort analysis of 54 consecutive patients who
underwent lower limb salvage surgery incorporating tumor endoprostheses (Stryker GMRS
system or DePuy Orthogenesis LPS system) at Vancouver General Hospital between 1990
and 2008. We compared the rates of radiographic loosening and revision among patients who
received perioperative chemotherapy and those who did not, then further analysed the effect of
cement fixation on these parameters. Inclusion criteria were: primary bone malignancy in the
lower limb and ≥2 years from index operation. Statistical analysis was performed using Fisher’s
exact test and Kaplan-Meier survivorship curves.
Results: Forty-three percent (23/54) of patients received perioperative chemotherapy and 57%
(31/54) did not. Eighty-one percent (44/54) of patients had cement fixation and 19% (10/54) did
not. Post-operative radiographs were not available for 4 patients. Radiographic evidence of
prosthesis loosening was present in 6/50 (12%). Revision surgery was required in 12/54 (22%)
patients, due to periprosthetic or prosthetic fracture (5/12), loosening (3/12), local recurrence
(2/12), recurrent joint instability (1/12), and infection (1/12). Using Fisher’s exact test,
perioperative chemotherapy did not affect the rate of radiographic loosening or revision for
loosening. It did, however, increase the total revision rate (p=0.02). Cement fixation resulted in
significantly less radiographic loosening (p=0.01) and trended towards reduced revisions for
loosening (p=0.08). It did not alter the total revision rate. Using Kaplan-Meier curves
chemotherapy was again shown to increase the total revision rate (p=0.03) but not revision
rate for loosening or radiographic loosening. Similarly, based on the curves, cement fixation
affected radiographic loosening (p <0.0001) and revisions for loosening (p=0.01) but not total
revision rate. When stratifying chemotherapy and non-chemotherapy groups by cement
fixation, use of cement was found to significantly reduce radiographic loosening (p=0.001) and
revision for loosening (p=0.016) in both. Use of cement did not however reduce the total
revision rate in either the chemotherapy or non-chemotherapy groups.
Conclusion: Use of chemotherapy increases the total revision rate of tumour endoprostheses
but not aseptic loosening. Cement fixation has lower rates of radiographic loosening and
revision for loosening in tumour endoprostheses regardless of whether chemotherapy is given
concurrently. We recommend the use of cement for prosthetic fixation as it improves construct
stability regardless of chemotherapy use.
164: Giant Cell Tumor Arising in the Distal Tibia
Saleh A Alsulaimani, QC; Peter Ferguson, ON; Jay S Wunder, ON; Marc Isler, QC; Sophie
Mottard, QC; Joel M Werier, ON; Benjamin Deheshi, ON; Norbert Dion, QC; Michelle Ghert,
ON; Robert Turcotte, QC
Purpose: To assess the management and outcome of distal Tibia GCT
Method: Patients with distal Tibia GCT managed in Canadian bone tumor centers.
Results: 32 patients were recorded between 1991 and 2010. There were 28 primary tumors
and 4 were recurrent lesions. The mean follow up was 5 years (1– 16). The mean age was 34
yrs (15-63). Radiographic grading was 3 grade 1 , 19 grade 2 ,9 in grade 3 and 2
indeterminate. The mean largest diameter was 3.3cm (1-12 cm). 5 presented with minimally
displaced fractures (4 extra articular). Mean Initial MSTS score was 27 (23-35) and the mean
initial TESS was 77.74 (45-100). All lesions were managed with curettage. High Speed Burring
was used for 31 pts. Hydrogen Peroxide was used on 3 pts, phenol in 5 pts and liquid nitrogen
in one. Pulsated lavage was recorded in 11 pts. The cavity was filled with cement only in 5,
cement and allograft in 3, 15 had morselized auto/allograft including 4 with the addition of strut
allografts. 14 were supplemented with internal fixation. None received radiotherapy. Postoperative complications included one infection and one non-union. 9 patients developed local
recurrence. They were all managed with additional curettage. Cement was used in 8 and
morselized allograft in one. None required additional internal fixation and one received postoperative radiotherapy. No complication was recorded in this group. 3 pts went to develop an
additional local recurrence. Again all were curetted without internal fixation and cement was
used in 2. One also got radiotherapy. No complication occurred. No lung metastases
developed. At latest follow up 29 were alive without evidence of disease, 2 were alive with
disease and 1 pt died from an unrelated cause. The mean final MSTS score was 32 (25-35)
and the mean TESS final score was 88 (35-100).
Conclusion: Giant cell tumor involved rarely the distal tibia. Curettage was possible in all but
with a high incidence of recurrence. Ultimate function was found very good.
165: Giant Cell Tumour of the Distal Radius: A Review of 75 Cases
Krista Goulding, ON; Ajay Puri, IN; Ashish Gulia, IN
Purpose: Giant cell tumor (GCT) of the distal radius is a rare, benign disease whose
propensity for locally aggressive behavior and recurrence has rendered decisions on treatment
modalities challenging. The objective of the study was to evaluate different surgical modalities
based on their recurrence rates and functional outcome to ascertain best practices for this
disease.
Method: Seventy-five consecutive patients (37 females; 38 males) presenting with a GCT of
the distal radius between September 2005 and February 2011 were retrospectively analyzed.
Thirty-eight patients presented with a primary GCT, while 37 had recurrences initially treated at
peripheral hospitals. Grade 3 Campanacci lesions were present in 53 patients. Thirty-five
patients had an intralesional excision (curettage with bone grafting (23) or cementing (12)),
and 39 patients underwent resection and reconstruction (arthrodesis using iliac crest (2), nonvascularized fibula (6), ulnar translocation (31) and prosthetic replacement (1)). One patient
required an amputation. The mean follow-up for all patients was 24 months (range, 1 to 106).
Patients were evaluated for recurrence with local and systemic staging, and local function
using MSTS scores.
Results: Nineteen patients (25.3%) had a local recurrence (LR); 14 cases were multiple. LR
rates in the primary GCT group as compared to the recurrence group were 14.7% and 10.7%,
respectively (p<0.05). For those patients undergoing wide resection, LR rates were 20.0%,
versus 40.0% after intralesional excision (p<0.005). Campanacci Grade 3 lesions recurred in16
of 53 cases, or 30.0%. This was significantly higher than in Grades 1 and 2, which had a LR in
5 of 22 (22.7%) (p<0.05). Four patients required conversion from curettage to wide resection
and arthrodesis, and two developed lung metastases, one of which underwent a
metastatectomy. The mean MSTS score was 27.4 in the curettage group and 25.9 in the wide
resection group (p=0.3).
Conclusion: GCT is an aggressive primary bone tumor with high rates of recurrence. Previous
intervention, intralesional excision and Grade 3 Campanacci lesions increase the risk of local
recurrence. Similar functional results were observed in both intralesional excision and wide
resection with arthrodesis. Wide resection is the preferred option for Campanacci Grade 3
lesions, and ulnar translocation provides an acceptable reconstruction method with good
functional outcomes.
166: Risk Factors for Local Recurrence Following Resection of Superficial Soft Tissue
Sarcomas: A Review of 467 Patients
William Eward, ON; Anthony Griffin, ON; Patrick O'Donnell, ON; Peter Chung, ON; Charles
Catton, ON; Brian O'Sullivan, ON; Jay S Wunder, ON; Peter Ferguson, ON
Purpose: Soft tissue sarcomas are most frequently located deep within fascial compartments
of the extremities. Superficial soft tissue sarcomas are relatively less common. They may be
managed differently than deep sarcomas because generous margins are often possible
without sacrificing critical structures. Radiotherapy may be utilized less often because of these
generous margins. However, small superficial soft tissue sarcomas are often not promptly
recognized as such and may be frequently treated with inadequate oncologic excision prior to
referral to a sarcoma centre. The effect of these factors on local control has not been well
documented.
Method: We reviewed 467 patients with superficial soft tissue sarcoma from our prospectively
maintained database at the University of Toronto/Mount Sinai Hospital between 1989 and
2009. Minimum follow-up was 2 years. Mean follow up was ten years. Patients were assessed
for histologic tumour type, size, grade, location, adjuvant treatment, and prior surgery. These
factors were correlated with local or systemic recurrence, survival, and complications.
Results: The most commonly represented tumours were undifferentiated pleomorphic
sarcoma (UPS, 32 percent), leiomyosarcoma (16 percent), and dermatofibrosarcoma
protuberans (DFSP, 12 percent). There were 131 (28 percent) grade 1/3 tumours, 133 (28.5
percent) grade 2/3 tumours, and 202 (43 percent) grade 3/3 tumours. 423 tumours (91
percent) were excised with negative margins while 39 (8.4 percent) were excised with
microscopically positive margins and three (0.6 percent) were excised with grossly positive
margins. There were 31 (6.8 percent) local recurrences. 55 patients (12.1 percent) developed
distant metastatic disease following treatment. Having had surgery prior to referral to our
center was a risk factor for local recurrence (p=0.03) and this scenario accounted for 17 of the
31 local recurrences (54.8 percent). Relative risk for local recurrence by histopathological
diagnosis, grade, surgical margin, adjuvant therapy, and location are also reported.
Conclusion: Superficial soft tissue sarcomas are often treated differently from traditional deep
sarcomas. Because they are frequently not recognized as sarcomas, they are treated
inappropriately prior to referral to a sarcoma centre. Operative treatment prior to referral and
definitive diagnosis is a risk factor for local recurrence.
167: The Effect of the Nature of a Positive Margin on Local Recurrence for Extremity
Soft Tissue Sarcoma
Patrick O'Donnell, ON; Anthony M Griffin, ON; Peter Ferguson, ON; William C Eward, ON;
Peter W M Chung, ON; Charles N Catton, ON; Brian O'Sullivan, ON; Jay S Wunder, ON
Purpose: To evaluate the risk of local recurrence after extremity soft-tissue sarcoma (STS)
resection with positive surgical margins, and the safety of sparing adjacent critical structures in
this setting.
Method: 257 patients with extremity STS who had a positive resection margin were identified
from a prospective database of 1,458 patients. Patients with positive margins were stratified
into four groups, each representing a specific clinical scenario and thought to be associated
with increasing risk: 1) low-grade liposarcoma; 2) positive margins planned preoperatively to
preserve a critical structure (bone or major nerve or blood vessel); 3) positive margins on reexcision following a prior unplanned excision elsewhere; and 4) unplanned positive margins.
The rate of 10-year local recurrence-free survival was calculated for all groups.
Results: 10-year local recurrence-free survival decreased incrementally from group 1 to group
4 (92.7% to 64.9%; p < 0.01). The rate of local recurrence-free survival following planned
positive margins to preserve critical structures (79.8%; group 2) was significantly higher than
after positive margins following prior incomplete excision (69.3%; group3) or unplanned
positive margins (64.9%; group 4). In comparison, the 10-year local recurrence-free survival
after sarcoma excision with negative margins was 90.4%.
Conclusion: These results show that the risk of local recurrence after resection of a STS with
positive margins can be predicted based on the clinical context and supports this type of
classification. In addition salvage of critical structures including bone and major nerves and
vessels directly adjacent to STS is relatively safe when planned ahead as part of
multidisciplinary management.. This information carries important decision-making implications
for management of patients at risk of positive margin resection of a STS.
168: Ths Susceptibility of Human Bone and Soft Tissue Sarcoma to Vaccinia and
Maraba Oncolytic Virus
Joel M Werier, ON; Hesham Abdelbary, ON; Jovian Tsang, ON; Derek Butterwick, ON; Jay S
Wunder, ON; Jean-Simon Diallo, ON; John Bell, ON
Purpose: Oncolytic viruses (OV) in cancer therapeutics has provided a novel approach to the
treatment of malignancies. These viruses preferentially infect, replicate and kill malignant cells,
while sparing healthy tissue. Oncolytic viruses have demonstrated a good safety record and
have a lesser adverse side affect profile compared to cytotoxic chemotherapy regimens. To
date, the majority of OV research has been directed towards various carcinoma models. The
susceptibility of sarcoma to oncolytic virus infection has not been fully characterized. The
purpose of this study is to characterize the infective potential of Vaccinia and Maraba virus and
in a heterogenic sarcoma panel.
Method: Fresh untreated sarcoma samples were collected from both open biopsies and
tumour resections. All samples were confirmed to be viable using the Alamar Blue viability
assay. Each sample was pre-treated with Suberoylanilide Hydroxamic acid (SAHA) or
Trichostatin A(TSA), pro-drugs (histone de-acetylase inhibitors) which may potentiate viral
infection. Samples were then infected ex-vivo with a commercially available Vaccinia virus, and
Maraba virus. After an incubation period, samples were collected for viral tittering and
examined for Green Fluorescence Protein, confirming the presence of infection. Unaffected
muscle biopsies were collected as controls. Thirty-six sarcoma samples were infected with
Vaccinia and 31 sarcoma samples were infected with Maraba. A viable infection was defined
by a 10-fold increase of viral production after incubation.
Results: Seventy nine percent of Maraba samples demonstrated viable infection compared to
27% of Vaccinia samples. Maraba infected samples demonstrated fold increases in vital titers
compared to Vaccinia infected samples. There was meaningful infection in a wide range of
sarcoma subtypes including high grade undifferentiated pleomorphic sarcoma,
rhabdomyosarcoma, osteosarcoma, and synovial sarcoma. Healthy muscle tissue collected
from the same patient did not show infection. The addition of a pro drug did not enhance
infection.
Conclusion: Vaccinia and Maraba demonstrated strong infectivity in selected sarcomas
samples. Maraba infected a higher percentage of sarcoma subtypes and produced higher vital
titers. Further investigation of Vaccinia and Maraba virus as potential therapeutic agent for
sarcoma therapy is warranted
169: Early Outcomes with Reverse Total Shoulder Arthroplasty in Patients with
Rheumatoid Arthritis
Danny P Goel, BC; Robert B Butler, US; Anup A Shah, US; Rachel Fowler, US; Jon JP
Warner, US; Laurence D Higgins, US
Purpose: The purpose of this study was to evaluate the indications for and report the
subjective and objective outcomes following reverse total shoulder in the rheumatoid
population.
Method: A retrospective chart review identified 19 rheumatoid patients which had undergone a
reverse total shoulder arthroplasty. Sixteen patients were available for prospective evaluation.
Eight patients were indicated for cuff tear arthropathy, 2 for fracture and 6 as revision surgery
for failed arthroplasty. All patients had routine follow up. Demographic information as well as
objective and subjective measures were recorded. Imaging studies were evaluated for the
presence of notching and loosening of the implants.
Results: Sixteen patients were included in the final analysis. There were 2 males and 14
females with an average age and follow up of 65.4 years (56-77) and 21.1 months (average 658 months), respectively. Range of motion improved in forward elevation from 42 to 94
degrees (p = 0.002), external rotation 17 to 29 (p = 0.1306) and internal rotation from side to
buttock (p = 0.0950). Visual analog scale and subjective shoulder value improved from 8.8 to
1.5 (p = 0.0001) and from 22.5 to 66.3 (p = 0.0014), respectively. Overall the majority of
patients were satisfied with their outcomes however 100% of primary inverse patients would
undergo surgery again whereas 86% or revision inverse patients would undergo surgery again.
Patients with revision procedures and those with complications had lower subjective and
objective outcomes compared to those with primary reverse arthroplasties. Notching was noted
in 56% of all patients (average notching Nerot stage 2). There was a 37% overall complication
rate where 5 out of 6 patients undergoing revision inverses had a complication (two patients
with dislocations, 1 patient with a post-operative periprosthetic fracture, 1 patients with base
plate loosening, 1 patient with radial nerve palsy).
Conclusion: Overall rheumatoid patients note objective and subjective improvements in pain
and function following reverse arthroplasty. The stratified outcomes remain highly dependent
on the indications for surgery. Although this low demand population generally does well, a high
complication rate is associated with revision of a previously failed implant.
170: Fractures of the Greater Tuberosity of the Humerus: A Study of Impact of Rotator
Cuff and Biceps Pathology on Function
Jennifer Mutch, QC; Luo Jun Wang, QC; Dominique M Rouleau, QC; G Yves Laflamme, QC;
Nicola Hagemeister, QC
Purpose: Dominique M Rouleau, MD, Msc., FRCSC: HSCM, Université de Montréal Outcome
after proximal humerus fracture is known to be variable. Fractures of the greater tuberosity
represent a particular challenge as the fragment serves as the insertion site for muscles of the
rotator cuff tendons and is the lateral floor of bicipital grove. Tendinomuscular injuries occurring
with fractures of the proximal humerus are of interest. MRIs performed after proximal humerus
fractures in general have shown an incidence of 40% full thickness rotator cuff tears. Bhatia
also reported 10% severe biceps tendinosis after greater tuberosity fixation. In addition, fatty
muscle atrophy has been shown to correlate with functional outcome in rotator cuff tears and
shoulder arthroplasty but no such study has been done following isolated greater tuberosity
fracture. The objective of this study is to evaluate the incidence of full thickness rotator cuff tear
and bicipital pathologies in patients with previous greater tuberosity fracture.
Method: A retrospective review of all cases of isolated greater tuberosity fractures seen from
2006 until December 2010 was performed. Patients with adequate initial and follow-up
radiographs of an isolated greater tuberosity fracture were invited to return for an ultrasound of
their affected shoulder. All of the ultrasounds were performed by the same experienced
musculoskeletal radiologist and the contralateral shoulder was used for comparison.
Tendinosis, tears, and position of the biceps tendon was noted and any partial or complete
rotator cuff tears were identified and measured. Quick DASH, SF12, WORC and pain score
were used to assess clinical outcome. Neer classification was used to classified fracture in
displaced or not displaced fracture.
Results: The 50 recruited patients had an average age of 58 (SD: 15, range 32-92) and 45%
were male. Sixty-six percent of the ultrasounds demonstrated at least one partial tear,
including 58% of patients under the age of 50. Six patients showed full thickness tear, all of
them were male. Biceps evaluation showed 11 subluxations and 28 tendinitis. Patients with full
thickness tear were having worst upper limb function as showed by the Q-DASH. (35 vs 16,
p=0.05) Also they were reporting more pain. (3.5/10 vs 1.7/10, p=0.05) The biceps subluxation
was associated with higher WORC score. (89 vs 73, p=0.05)
Conclusion: This study describes the tendinous pathology associated with isolated greater
tuberosity fractures of the proximal humerus. Following these fractures, a significant portion of
patients was shown to have rotator cuff pathology regardless of age. We don’t know if they are
secondary to the fracture or pre-existing pathologies, but they are related to worst outcome.
Patients with greater tuberosity fractures may benefit from additional imaging to evaluate their
rotator-cuff and biceps when expressing less favorable outcome. However, larger clinical
studies are needed to evaluate the functional impact of the associated rotator-cuff and biceps
injury.
171: Navigation Of Guidewire Placement Using Volume Slicing Of 3D Cone-Beam
Computed Tomography (CBCT) Images For Percutaneous Scaphoid Fixation
David Pichora, ON; Erin Smith, ON; Hisham A Al-Sanawi, ON; Braden Gammon, ON; Randy
E Ellis, ON
Purpose: Percutaneous scaphoid fixation (PSF) classically involves drilling a guidewire along
the scaphoid over which a cannulated screw is placed to stabilize the fracture. Stability is
linked to maximizing the length and central placement of the screw, yet is challenging due to
the small size and complex geometry of the bone; this typically results in liberal use of
conventional 2D fluoroscopic C-arm images for guidance. This study aimed to evaluate if
image-guidance technology can improve placement and reduce x-ray exposure in this
procedure.
Method: An in-vitro study was conducted to compare volume-sliced (VS) navigation to
conventional C-arm guidance (n=24). A model wrist featuring a replaceable scaphoid was
constructed to permit direct comparison between the two trial groups. Each trial involved
inserting a guidewire using a volar approach with the goal to maximize both central placement
and length of its position. Subsequently, the drilled scaphoids were CT-imaged to measure
length and depth of the guidewire path. A computer-algorithm was used to determine the paths
maximizing depth and length of the model scaphoid to compute an optimal target zone. Length
and depth of guidewire placement, drilling attempts and x-ray exposure were used as
comparative measures. In the VS technique a 3D digital angiographic C-arm was rotated 180
degrees to take an intraoperative 3D cone-beam x-ray (CBCT) image of the wrist. Using
computer algorithms, the 3D image was volume-rendered and sliced along the anatomical
planes to produce a 2D image series similar to CT slices; however unlike CT slices, the
viewing orientation, slice thickness and spacing could be varied. The surgeon used these
images to create a target plan by positioning a virtual screw on the 3D image. The image slices
were reconfigured in the plane of the target path for navigation. A drill guide equipped with
infrared markers allowed the orientation of the guidewire to be tracked by a camera during
drilling. A novel preoperative calibration step was used to show the real-time position of the
tracked drill relative to the VS images, avoiding patient-based registration characteristic of
most image-guided orthopaedic interventions.
Results: The VS group had a higher mean depth (i.e., central placement; p<0.05), but no
significant difference in length. There were 83.3% of navigated trials and 75.0% of the
conventional trials within the optimal zone. VS navigation demonstrated increased precision of
guidewire placement (p<0.05). Each VS trial required only one drilling attempt (p=0.00) and
resulted in less radiation exposure than conventional C-arm (p<0.01).
Conclusion: This study represented a preliminary evaluation of VS navigation using
intraoperative 3D CBCT for the purposes of scaphoid fracture repair. Initial results indicate
improved guidewire placement, with fewer drilling attempts and less radiation exposure than
the conventional technique. We are currently conducting ex-vivo trials and early clinical
application.
172: Prevalence of Symptoms of Depression, Panic Disorder and PTSD in an Injured
Worker Upper Extremity Clinic
Ryan M Degen, ON; Joy MacDermid, ON; James Roth, ON; Darren Drosdowech, ON; Ruby
Grewal, ON; Ken Faber, ON; George S Athwal, ON
Purpose: Depressive symptoms, anxiety and post-traumatic stress disorder have been
associated with musculoskeletal disorders and may act as barriers to recovery in injured
workers. Their frequency in this population is not known. The purpose of this study was to
identify the prevalence of depression, panic disorder (PD) and post-traumatic stress disorder
(PTSD) using the Patient Health Questionnaire (PHQ), a mental health screening tool, in a
cohort of patients presenting to an upper extremity injured-worker specialty clinic. A secondary
purpose was to investigate the relationship between PD, PTSD, depression and patient
reported outcomes.
Method: All patients completed the PHQ in conjunction with their initial evaluation by an upper
extremity orthopedic surgeon (n=418). Questionnaires completed during 2010 were reviewed.
Patients with a positive PHQ, containing domains assessing for depression, PD and PTSD,
were reviewed for demographics, diagnosis, self-efficacy scores, DASH and SF-36 scores.
The prevalence of each of these disorders, and their relationship with presenting complaints
and outcomes, were calculated.
Results: 130 patients (31.0%) scored positively on the PHQ; 87 patients (20.8%) for
depression, 57 (13.6%) for PD and 65 (15.5%) for PTSD. Patients presenting with neck pain
had a significantly higher prevalence of depression (p=0.012) and PD (p<0.001). Patients
diagnosed with chronic pain syndrome were found to have a significantly higher prevalence of
depression (p=0.014). Patients scoring positive for depression had lower SF-36 mental
component scores (p<0.001), and poorer QuickDASH (p=0.003) and DASH (p=0.007) work
scores compared to patients who scored positively on other domains of the PHQ, but
negatively for depression.
Conclusion: A third of patients presenting to the injured worker clinic screened positively for at
least one condition on the PHQ. Screening was effective at identifying patients with potential
blocks to recovery. Further studies are required to determine whether identification of these
mental health disorders can help direct appropriate referral and management and to assess
the effect on patient reported outcomes.
173: Fractures of the Greater Tuberosity of the Humerus: Validation of a New
Morphologic Classification
Jennifer Mutch, QC; Luo Jun Wang, QC; Dominique M Rouleau, QC; G Yves Laflamme, QC;
Nicola Hagemeister, QC
Purpose: Intro: Isolated fractures of the greater tuberosity are particular in that the fragment
serves as the insertion site for muscles of the rotator cuff. While previous studies have
demonstrated that as little as 2mm of superior displacement of the greater tuberosity may have
a significant negative impact on the function of the affected shoulder, little research has been
undertaken to determine whether the type, or morphology of the greater tuberosity fracture
affects outcome. Multiple classification systems based on fragment displacement have been
previously developed to describe greater tuberosity fractures. The most popular, by Neer,
categorizes fractures simply as displaced by more or less than 5mm. A third category, that of a
displaced greater tuberosity fracture associated with a glenohumeral dislocation, was later
added by the AO. Bahrs et al., however, recently proposed 3 mechanisms for greater
tuberosity fracture: avulsion, acromial impaction, and impaction on the glenoid. Using this and
our experience with greater tuberosity fractures and their radiographs, we proposed the
following new morphologic classification: 1) An avulsion involves small fragments of bone and
the fracture line is horizontal. 2) A depression fracture involves a fragment that is displaced
inferiorly. 3) A split fracture involves a large fragment with a vertical fracture line that extends
to or past the level of the surgical humeral neck.
Method: A retrospective review of all cases of isolated greater tuberosity fractures seen at our
Institution from 2006 until December 2010 was performed. One hundred thirty-nine cases with
adequate standard radiographs of the shoulder were identified. Three observers (an
orthopedic surgeon(YL), an orthopedic fellow(AC) and an orthopedic resident(JM))
independently categorized the 139 cases according to the Neer, the AO and the new
Morphologic classifications. This was done on two separate occasions with a minimum interval
of three weeks. The inter- and intra-observer reliability was then calculated using Randolph’s
free-marginal kappa (2005).
Results: The relative frequency of the avulsion, split, and depression fracture types was 0.45,
0.36 and 0.17 respectively. The average age of the patients at the time of injury was 58
(standard deviation (SD):15, range: 23-96) and this did not differ significantly among fracture
types. Sixty percent of the cases were female patients and this did not differ significantly
among fracture types. The incidence of dislocations, however, varied with fracture type and
was 21%, 26% and 57% for avulsion, split, and depression fracture types, respectively
(p<0.01). The inter-observer kappa was 0.31-0.35 for the Neer classification, 0.33-0.37 for the
AO classification and 0.6-0.84 for the Morphologic classification. The intra-observer kappa was
calculated for each of the observers (JM, AC, YL) and varied between 0.63-0.73, 0.72-0.77
and 0.73-0.88 for the Neer, AO, and Morphologic classifications, respectively.
Conclusion: This study describes a simple and reproducible classification system for isolated
fractures of the greater tuberosity: the Morphologic classification. It separates greater
tuberosity fractures into 3 distinct and easily identifiable groups: avulsion, split and depression.
The depression fracture type is associated with more glenohumeral dislocations than then
avulsion and split fracture types combined. However, larger clinical studies are needed to
evaluate the impact of these fracture types on functional outcome and on surgical strategies.
174: Infection Rate in Total Shoulder Replacement: Best Practices- Antibiotic cement
Danny P Goel, BC; Kevin Roth, US; James R Romanowski, US; Jessica Wells, US; Laurence
D Higgins, US; Jon J P Warner, US
Purpose: Deep infection of primary total shoulder arthroplasty (TSA) is a rare but potentially
devastating complication. The reported prevalence in the literature ranges from 0% to 15.4%.
At present, antibiotic impregnated cement is approved for use in second-stage reimplantation
after infection. The primary use in TSA is not considered standard of care. This is in contrast to
the total hip arthroplasty literature, which has documented a lower deep infection rate following
primary arthroplasty. To our knowledge, no report exists of infection rates following primary
total shoulder arthroplasty with the use of antibiotic impregnated cement. We hypothesize that
the primary use of antibiotic impregnated cement in combination with standard intravenous
antibiotics would decrease the rate of infection following primary total shoulder arthroplasty.
Method: A single shoulder surgeon’s complete primary TSA experience was retrospectively
reviewed. The presence or absence of a post-operative infection was recorded. All patients
having undergone primary TSA were included in the study. Previous arthroscopic surgery was
not an exclusion criteria. Revision procedures were excluded. Demographic data, operative
information as well as post-operative follow up were included.
Results: Between 1999 and 2009, 603 TSA were performed by the senior surgeon. A total of
311procedures were primary TSA where 153 were without antibiotic impregnated cement
(Group A) and 158 with (Group B)). There was no statistically significant difference in age,
operative time or gender distribution between the two groups. At latest follow up, in Group A,
10 (6.5%) shoulders developed a deep infection. In Group B, only 1 (0.6%) shoulder
developed a post-operative infection. Neither age, operative side, nor surgical time influenced
the development of an infection.
Conclusion: The present study retrospectively evaluated every primary TSA performed by a
single surgeon at a single institution. Approximately half of these TSAs were performed without
the use of antibiotic cement, and half were performed with antibiotic cement. There was a
strongly statistically significant relationship between the institution of antibiotic cement and the
decrease in infection, p=0.0029. There was no statistically significant difference between the
groups in terms of age, sex or operative side. Age, sex and operative side were each
completely independent of the development of infection. These findings corroborate outcomes
seen in the total knee and hip literature, and support the hypothesis that antibiotic impregnated
cement is efficacious in the prevention of deep peri-prosthetic infection in primary total
shoulder arthroplasty.
175: Intra- and Inter-Rater Reliability of the Detection of Full-Thickness Tears of the
Supraspinatus Central Tendon by Shoulder Surgeons and Musculoskeletal Radiologists
John A Grant, US; Bruce S Miller, US; Yoav Morag, US; Jon Jacobson, US; James E
Carpenter, US
Purpose: Recent evidence suggests that tears of the supraspinatus intramuscular central
tendon demonstrated on MRI are more likely to fail with conservative management. The
accuracy and agreement in identifying a tear of the supraspinatus intramuscular central tendon
on MRI is unknown. The purpose of the current study was to determine the intra- and interrater reliability of detecting a full tear of the supraspinatus central tendon on MRI by
orthopaedic shoulder surgeons.
Method: The de-identified coronal and sagittal plane MRIs from 40 patients entered into a
prospective rotator cuff tear database were independently reviewed by two MSK radiologists in
order to identify examples of an intact supraspinatus central tendon, a partial-thickness tear, or
a full-thickness tear of the central tendon. MRIs from these patients were randomly sorted and
distributed on CD to 16 members of the MOON (Multi-center Orthopaedic Outcomes Network)
Shoulder group. Members were also sent an educational presentation including anatomical
information about the central tendon and examples of a normal tendon, partial thickness, and
full-thickness tear. Members were asked to characterize each patient as having no tear, a
partial tear, or a full thickness tear of the central tendon. After a one month interval, the
members were sent a new set of CDs with the MRIs randomly reordered and were again
asked to diagnose the status of the central tendon. Intra-rater (round 1 vs. round 2) and interrater (within round 1 and round 2 separately) reliability were determined with the kappa
statistic. Agreement and inter-rater reliability were also determined between the shoulder
surgeons and radiologists.
Results: The intra-rater reliability was excellent (0.86 ± 0.11, 95% CI: 0.81, 0.91). The
agreement was 93.5% ± 4.8, 95% CI: 91.1, 95.9. Inter-rater reliability for both rounds was also
excellent (0.77 & 0.73). The agreement between the shoulder surgeons and radiologists was
92.6% ± 3.9, 95% CI: 90.7, 94.6. The inter-rater reliability between the surgeons and
radiologists was excellent (0.84 ± 0.08, 95% CI: 0.80, 0.89). Stratifying partial tears from no
tears resulted in lower intra-rater reliability (0.72 ± 0.13, 95% CI: 0.65, 0.79) and inter-rater
reliability between surgeons (0.59) and between surgeons and radiologists (0.66 ± 0.09, 95%
CI: 0.61, 0.71).
Conclusion: The intra-rater reliability and inter-rater reliability between shoulder surgeons,
and the inter-rater reliability between shoulder surgeons and MSK radiologists, was excellent
for the detection of full thickness tears of the central tendon of the supraspinatus. Since there
is agreement among orthopaedic surgeons and radiologists about the condition of the
supraspinatus central tendon on MRI, this parameter can be studied as a possible predictor of
outcome from conservative treatment for rotator cuff tears.
176: Lesser Tuberosity Osteotomy vs. Subscapularis Tenotomy in Shoulder
Arthroplasty: Healing Rates and Fat Infiltration
George S Athwal, ON; Peter LC Lapner, ON; Elham Sabri, ON; Kawan Rahkra, ON; Kimberly
Bell, ON
Purpose: Controversy exists regarding the optimal technique of subscapularis mobilization
during shoulder arthroplasty. The purpose of this study is to compare healing rates and fatty
infiltration in patients enrolled in a multicentre randomized double-blind study comparing lesser
tuberosity osteotomy (LTO) to subscapularis tenotomy (ST).
Method: Eighty-seven patients undergoing shoulder arthroplasty were randomized to receive
either a LTO or ST. Follow-up CT scans were conducted 12 months post-operatively and
radiographic outcome variables included healing rates and subscapularis Goutallier fatty
infiltration grade.
Results: CT imaging was available in 63% of the cohort. Baseline demographic data did not
differ between groups for sex (p=0.72), affected side (p=0.59) or arthroplasty type
(hemiarthroplasty or total, p=0.61), however, age differed significantly (ST, 65.3 years, LTO,
70.4 years, p=0.03). The healing rate for ST (96%) and for LTO (90%) did not differ
significantly between groups (p=0.62). The Goutallier mean fatty infiltration grade postoperatively for ST (0.58) did not differ significantly from LTO (0.73) (p=0.46). Overall, there was
a one-grade increase in fatty infiltration from pre-operative CT to post-operative imaging for the
ST group, and a 0.5 grade increase in the LTO group
Conclusion: No statistically significant differences were observed in the healing rates or fatty
infiltration grades between and the ST and LTO. This trial does not demonstrate any clear
difference in radiographic outcomes of one subscapularis management technique over the
other.
177: Sensitivity and Specificity of a New Clinical Test for Intra-articular Long Head
Biceps Pathology
Rachel A Schachar, AB; Kristie More, AB; Ian Lo, AB; Robert Hollinshead, AB; Richard
Boorman, AB
Purpose: To determine the sensitivity and specificity of a new clinical test, the Saw test,
designed to diagnose intra-articular pathology of the long head biceps (LHB) tendon and
compare this to previously described clinical tests (Speed’s and Yergason’s).
Method: One hundred forty-nine patients from three shoulder surgeon’s practices at the
University of Calgary Sport Medicine Centre who consented to undergo arthroscopic shoulder
surgery were included. The Saw test is a dynamic test done with the patient lifting up on the
examiner's hand with their forearm supinated and elbow flexed 90 degrees. The patient flexes
and extends their shoulder, through a 60-degree range of motion (30 degrees of flexion and 30
degrees of extension) while maintaining elbow flexion and forearm supination. This maneuver
is designed to maximally load the LHB tendon through a range of motion, within the bicipital
groove. A test is considered positive if the patient has pain in the anterior aspect of the
shoulder, radiating into the biceps while performing the test. If lateral or posterior pain is
elicited, the Saw test is considered negative.Independant examiners were specifically trained
by the principle investigator to perform the clinical tests in a standardized manor. The blinded
examiners performed the clinical assessment on each patient just prior to arthroscopy. The
assessment included the Yergason’s test, Speed’s test, and the new Saw test. Results were
recorded on a data collection form and kept unknown to the surgeon. Diagnostic arthroscopy
was then performed by the surgeon and included a thorough systematic exam of all shoulder
joint structures. Documentation of all joint pathology (including LHB pathology), and
procedures performed was made on a form separate from the clinical assessment form.
Intraoperative photographs were taken. Arthroscopic findings were considered to be the “true”
condition for analysis.
Results: One hundred forty-nine patients (87 males and 54 females) were included. Mean age
was 49.6 (SD = 14.9). Following arthroscopy intra-articular LHB pathology was found in 93
patients (62.4%), whereas 56 patients (37.6%) had a normal LHB tendon. When examined for
presence or absence of LHB pathology, the sensitivity of the specials tests was: Saw – 56%,
Speed’s – 52% and Yergason’s – 37%. Specificity was: Saw – 66%, Speed’s – 71% and
Yergason’s – 84%. When examined as an indicator for LHB surgical intervention (i.e.
debridement, release, or tenodesis), the sensitivity of the special tests was: Saw – 61%,
Speed’s – 55% and Yergason’s – 38%. The specificity was: Saw – 60%, Speed’s – 64% and
Yergason’s 76%.
Conclusion: Our results are consistent with previously published sensitivity and specificity
rates for the Speed’s and Yergason’s tests. The new Saw test showed the highest sensitivity in
regard to presence or absence of LHB pathology, as well as requirement for LHB surgical
intervention. Use of the SAW test may be helpful for surgical decision making in the clinical
setting.
178: Subacute Scaphoid Fractures: Factors Predictive of Successful Non-operative
Treatment
Richard P Nadeau, ON; Nina Suh, ON; Ruby Grewal, ON
Purpose: The purpose of this study was to determine factors predictive of successful nonoperative treatment for subacute scaphoid fractures.
Method: A departmental radiology database was searched to identify all scaphoid fractures
imaged at our institution from 2006 to 2010. A retrospective chart review was conducted for all
identified patients. Scaphoid fractures presenting between six weeks to six months from initial
injury were included in this study. Their medical records, x-rays, and CT scans were reviewed
and followed until union was achieved or non-union was confirmed.
Results: Thirty-nine patients met our inclusion criteria with 3 being lost to follow-up. The mean
age was 28 (range: 12-65) and 75% were male (n=27). There were 10 proximal pole fractures,
25 waist fractures and one distal pole fracture. The average delay from injury to the initiation of
treatment was 12 weeks (range 6-23 weeks). The relative risk (RR) of non-union increased
significantly with the presence of an underlying humpback deformity (RR=3) or with sclerosis
along the fracture line (RR=2.5). Patients with underlying diabetes also had a greater risk of
non-union (RR=2.6). Interestingly, fractures involving the proximal pole (RR=1.3), fractures
with cysts identified on CT scan (RR=1) or fractures with 1 to 4 mm of displacement (RR=1.8)
did not demonstrate an increased risk of non-union. Seventy-five percent of those that healed
successfully with conservative treatment did so by 13.5 weeks. They presented slightly sooner
(11 vs. 14 weeks delay to presentation, p=0.05) and required significantly less time in the cast
(10 vs. 26 weeks, p=0.004).
Conclusion: In the absence of a humpback deformity, sclerosis, and underlying diabetes,
scaphoid fractures presenting within six weeks to six months from their initial injury can be
successfully treated with casting alone, despite the presence of cystic changes on CT scan.
179: A Prospective Study on Functional Outcome of Percutaneous Epiduroscopic
Adhesiolysis Compared to Lumbar Spine Surgery for Treatment of Failed Back Lumbar
Syndrome Caused by Fibrosis –Adhesion
Ahmed AbdulAmeer Alkhuzai, IQ
Purpose: Epidural fibrosis and adhesion seen as common post lumbar syndrome phenomena
which contribute to 50%-60% recurrent of the symptoms. Aim of Study: We studied the
effectiveness of percutaneous epiduroscopic adhesiolysis in management of fibrosis &
adhesion resultant from failed backed lumbar spine surgery compared to second time surgical
decompression with surgical excision of the fibrosis of lumbar spinal stenosis.
Method: In a prospective comparative study of 44 patients all of them with failed backed post
laminectomy syndrome were diagnosed according to magnetic resonance imaging, also
according to inclusion exclusion criteria in diagnosis of adhesion with fibrosis, were
randomized into two groups .Group A treated by lumbar spine surgery with second time
surgical exploration ,decompression and excision of fibrosis compared to the second group B
were treated by percutaneous epiduroscopic adhesiolysis through sacral canal under
fluoroscopic guide .The caudal epidurogram showed restriction in spread of contrast caused by
fibrosis & adhesion then the canal open by irrigation through pressurized saline range from 40
to 80 ml according to the number of the level which were obstructed by fibrosis .Saline used
intermittently until the spinal canal open were seen by fluoroscope until complete procedure
with adequate adhesiolysis with visualization of the canal opening .At the end of the procedure
solutions were used to decrease rate of adhesion .Depomedrol 80 mg 2ml ,Hyaluronate 6ml,
1% 5ml lignocaine injected into canal space.
Results: Improvement in contrast filling defects of the epidural space was noticed during
treatment by percutaneous epiduroscopic adhesiolysis combined to improvement in pain, short
term & long term compared to second time lumbar spinal surgery. Results: In both group A by
surgical procedure & B percutaneous epiduroscopic adhesiolysis were noticed significant
improvement in the mean of Stanford score and ODI (Oswestry low back disability score) from
baseline were at all follow up visit for 24 Months according to sciatica pain (short term less
than 6 Months, long term more than 6 Months), Functional outcome, Return back to work,
psychological status, Change in narcotic intake, with the general satisfaction rate. Also there
were significant statistical differences at 12, 24 Months follow up for both Stanford and ODI
Oswestry index between group A and group B revealed high outcome results for group B was
treated by epiduroscopic adhesiolysis technique (P- value <0.0001) with minimal complications
rate in group B compared to group A.
Conclusion: We concluded that percutaneous epiduroscopic adhesiolysis for 2 years follow
up are superior to the surgical exploration with excision of fibrosis & second time
decompression in treatment of failed back lumbar spinal surgery.
180: Adverse Event Rates of Surgically Treated Cervical Spondylopathic Myelopathy
John T Street, BC; Dennis Hartig, BC; Juliet Batke, BC; Michael Boyd, BC; Marcel Dvorak,
BC; Charles Fisher, BC; Brian Kwon, BC; Scott Paquette, BC
Purpose: In recent years an increased understanding of the natural history of Cervical
Spondylopathic Myelopathy (CSM) in parallel with advancements in anaesthetic and
perioperative practice have led to broadened surgical indications and more aggressive surgical
management. As Canadian demographics, particularly population age and ethnicity, continue
to change the surgical burden of CSM will continue to increase. Identification of treatment
Adverse Events (AE’s) is critical to objective measurement of surgical utility. We are unaware
of any published prospective data specifically quantifying the risk of intraoperative and
postoperative adverse eventsfor surgically treated CSM.
Method: Data was collected prospectively over a three year period (2008-2010) at our
institution on all patients with surgically treated CSM. AE data was collected prospectively
during the peri-operative period until discharge using the previously validated SAVES tool. All
AE’s were reviewed at a weekly, attending lead, multi-disciplinary adverse events review
meeting. 113 patients (81 male, 32 female) with complete SAVES data were identified. Of
these patients 43 (38%) were confirmed discharged without an AE being recorded. The
remaining 70 patients accrued 105 AE’s in total during their inpatient stay (1.5 AE’s per
patient).
Results: The most common intra-operative AE’s were hardware mal-position requiring revision
(3.3%) and dural tear (1.7%). The most common postoperative AE’s were dysphagia (11.7%),
urinary tract infection (11.7%) and postoperative neuropathic pain (10%). Pneumonia was
reported in 5% and wound infections in 5%.
Conclusion: A significant trend was identified demonstrating increased rate of AE’s in older
patients and those with more severe disease prior to surgery. This data should prove helpful in
the pre-operative counselling of patients in terms of the absolute risk of AE’s as well as the risk
of specific AE’s.
181: Cost-Effectiveness Analysis of a Reduction in Diagnostic Imaging in Degenerative
Spinal Disorders
Raja Rampersaud, ON; Joanne S M Kim, ON; Joyce Z Dong, ON; Stacey Brener, ON; Peter
C Coyte, ON
Purpose: Advanced imaging technologies such as computed tomography (CT) and magnetic
resonance imaging (MRI) are highly sensitive, but often non-specific, diagnostic tools. Despite
this, CT and MRI are over-utilized in degenerative spinal disorder diagnosis. The purpose of
this study was to determine if stronger adherence to the 2001 Ontario guidelines would reduce
CT and MRI usage in spinal disorder diagnosis and be cost-effective from the perspective of
the Ministry of Health.
Method: Diagnostic and surgical data were prospectively collected on 2,046 outpatients who
received consultation with the senior surgical author at Toronto Western Hospital, between
September 2005 and April 2008. Using these data, we modelled an evidence-based diagnostic
triage program (implemented within existing infrastructure) wherein spine-focused clinical
assessments by advance practice allied health personnel and plain X-ray imaging would be
applied prior to CT and MRI. Incremental costs were the incurred expenses from additional
consultations and plain X-rays less the cost savings from the eliminated CT and MRI scans,
expressed in 2009 Canadian dollars. Outcomes were expressed as the number of surgical
candidates identified per MRI used in diagnosis, reflecting the efficiency of diagnostic imaging.
Sensitivity analyses were performed by varying the unit cost of an spine MRI and the
proportion of patients who had undergone plain x-ray or CT prior to assessment.
Results: The triage program incurred $109,720 from additional consultations and plain X-rays
and saved $2,117,697 from eliminated CT and MRI scans, resulting in net cost savings of
$2,007,977 for the 31 months of study period or $777,282 per year. In usual care, 0.328~0.418
surgical candidates were identified per MRI whereas in the triage program, 0.736~0.885
surgical candidates were identified per MRI, resulting in over a two-fold improvement in MRI
efficiency. The triage program still resulted in net cost savings, even at the implausible
extremes of our sensitivity analysis. The triage program was therefore dominating. Applying to
“high” volume spine surgeons in Ontario, we estimated that the implementation of the triage
program would save the province $24,234,929 per year.
Conclusion: Eliminating unnecessary imaging in spinal disorder diagnosis referred to a spine
surgeon can save provincial health care significant resources, while providing improved patient
access and care.
182: Dynamic Stabilization with an Interspinous Spacer as an Alternative to Arthrodesis
for Lumbar Degenerative Disorders
Edward P Abraham, NB; Neil Manson, NB; Renee Elliot, NB; Melissa Mckeon, NB
Purpose: DIAM (Device for Intervertebral Assisted Motion - Medtronic) is a flexible silicone
interspinous spacer providing stability and preserving motion for herniation of the nucleus
pulposis (HNP) and providing relief of neurogenic claudication secondary to lumbar spinal
stenosis (LSS) with or without degenerative spondylolisthesis (DS). In addition to surgical
decompression, arthrodesis is often considered as an adjunct in patients who have central or
recurrent HNP and in cases of LSS requiring more extensive decompression. DIAM
implantation, performed as a day surgery procedure, was used in cases of HNP and LSS as an
alternative to arthrodesis. The purpose of this study was to evaluate the clinical benefit of the
use of DIAM in patients undergoing decompression necessary to address symptoms of central
or recurrent HNP or LSS who would otherwise have been considered for arthrodesis.
Method: Fifty-three patients between 2007-09 with HNP or LSS were considered for
decompression and fusion but were offered alternative treatment in the form of decompression
and DIAM performed as a day surgery procedure at a single institution. Preoperative Oswestry
Disability Index (ODI), SF-36, VAS back and leg scores were compared to values at 1.5, 3, 6,
12 and 24 months post-op. The average follow-up was 3.5 years with a minimum of 2 years.
Inclusion criteria consisted of patients with single level pathology and either HNP (central or
recurrent) or LSS (with or without DS). Exclusion criteria consisted of patients with multilevel
disease and or significant deformity. Statistical significance between pre-op and post-op values
were calculated and the need for reoperation and other complications were evaluated. The
primary outcome measurement was the ODI and was felt to be clinically significant if a
reduction of 30% was observed. SF-36, VAS were also part of the analysis.
Results: Forty-nine of 53 (92%) of patients were available for the minimum 2 year follow-up.
For the primary outcome, statistically significant improvements were noted for ODI exceeding
the minimum 30% improvement at all follow-up intervals post-op (p<0.05). SF-36 , VAS back
and leg pain scores also improved at a high level of statistical significance (p<0.05) at all time
points compared to pre-op. Three failures were identified necessitating further surgery recurrent HNP in 2 patients (requiring arthrodesis) and sepsis in one patient (implant
extraction). There were no complications on the day of surgery necessitating admission to
hospital. Significant success was observed in 46/49 (94%) patients based on two year
outcomes demonstrating potential longer term survival for the implant and clinical
improvement.
Conclusion: DIAM with decompression as a day surgery procedure can provide clinical
benefit two years post implantation in patients with single level HNP (central or recurrent) or
LSS (with or without DS) as an adjunct to decompression where arthrodesis might be
considered. Potential cost savings are possible.
183: MIS Lumbar Fusion for Low-grade Isthmic and Degenerative Spondylolisthesis: 2-5
year Follow-up
Simon A Harris, ON; Raja Rampersaud, ON
Purpose: Minimally Invasive Surgeries (MIS) for lumbar spondylolisthesis (LS) have been
shown to be safe and efficacious in the short term but little is know about the intermediate or
long-term clinical success.
Method: A retrospective cohort analysis was performed on prospectively collected data from
patients undergoing one or two-level MIS lumbar fusion for low-grade LS. Surgeries were
performed from 2005-2009 by a single surgeon. Global Satisfaction Rating (GSR), Oswestry
Disability Index (ODI) and Short Form-36 (SF36) scores were evaluated pre-operatively and
post-operatively at six weeks, three, six, 12, 24, 36, 48 and 60 months. Receiver Operating
Characteristic curves were used to evaluate SF36 component sub-scores at two years with
‘success’ anchored to GSR. For each SF36 component, the two-year score and the two-year
Norm-Based Score (NBS; age and sex matched to normal Canadian equivalents) were
analysed.
Results: 66 patients where at, or over, two-year follow-up. The mean age at surgery was 54
years, 44.2% female and mean follow-up was 3.58 years. Baseline ODI scores (n=66, mean
38.32% [95% CI 42.01-33.99]) continued to improve until two years post-operative (n=66,
mean 17.24% [95% CI 13.26-20.80]) and are maintained to five years (n=27, mean 16.81%
[95% CI 10.03-23.60]). The ROC curve analysis of two-year SF36 component scores identified
Physical Functioning (Cut-Off Score 50; Area Under Curve 0.89; Sensitivity 0.78; Specificity
0.84) and Bodily Pain (COS 41; AUC 0.88; Sensitivity 0.77; Specificity 0.86) as the strongest
correlates of satisfaction. The COS for the two-year SF36 NBS components that correlated
best with satisfaction, were consistently one standard deviation below their Canadian age and
sex-matched equivalents.
Conclusion: The benefits of MIS lumbar fusion for low-grade spondylolisthesis are maintained
for two to five years. Despite SF36 component scores below their mean Canadian age and
sex-matched equivalents, 85.7% of patients were satisfied with their outcome.
184: Preventions of Technical Complications During Retrorectal Presacral Approach for
Lumbosacral Axial Instrumentation
Kalliopi Alpantaki, GR; Pavlos Katonis, GR; Alexander Hadjipavlou, GR; George Vastardis,
GR; Nick Benardos, GR
Purpose: This is prospective study and literature review which aims to quantify the risks and
the complications associated with AxiaLIF in a series of 29 patients and to highlight the
reported complications in the literature.
Method: The complications in a series of 29 patients treated with AxiaLif were analyzed. Also
the reported complications in the literature until October 2010, was examined in order to
establish technical guidelines for prevention of surgical pitfalls
Results: Fusion rate in the present series was 92%.Complications included presacral
hematoma: 1 (3,5%).Symptomatic subsidence, occurred in the stand alone group, resulted in
foraminal stenosis and radiculopathy in two patients (7%) and back pain in one (3,5%). One
patient (3,5%) developed painful radiolucent halo around the rod in a spondylolytic case which
resolved after transpedicular instrumentation. Literature review revealed only 23 manuscript
and 53 abstracts, all retrospective level IV studies. According to FDA reports the most dreadful
complication was rectal perforation in 55 patients. The rest were some asymptomatic
subsidences, posterior graft extrusion (1,1%- 3,3%), hematoma (1,8%), implant radiolucency
(3,9%) and insignificant number of ureteral and vascular injuries. Fusion rates ranged from
68% to 100%.
Conclusion: AxiaLIF is a novel truly minimally invasive technique not requiring blood
transfusion and can be safely performed as a day surgery. Retroperitoneal hematoma, ureteral
and vascular injuries can be avoided by respecting the regional anatomical landmarks as
guided by accurate fluoroscopy. Only expanding hematoma may be drained. Bowel perforation
can be prevented by gently sweeping away the rectum from the sacrum before inserting the
guide probe.
185: Prospective Analysis of Adverse Events in Surgical Treatment of Degenerative
Spondylolisthesis
Adrienne M Kelly, BC; Juliet Batke, BC; Michael Boyd, BC; Marcel Dvorak, BC; Charles
Fisher, BC; Brian Kwon, BC; Scott Paquette, BC; John T Street, BC
Purpose: Surgical literature traditionally focuses on outcomes and comparisons of specific
procedures. There is a paucity of data on outcomes and adverse events (AEs) in the context of
the presenting diagnosis. Such condition-specific AE information would greatly facilitate
informed consent. Specific intra- or post-operative AEs independently associated with a
diagnosis of degenerative spondylolisthesis (DS) have never been examined, and the AE data
that is available, by virtue of the methods of identification, are substantially underreported. This
study prospectively assesses the AE profile of a cohort of surgical-treated patients with a
primary diagnosis of L4-5 DS, with the secondary aim of identifying risk factors that correlate
with those adverse events.
Method: Prospective AE data using the SAVES tool on patients surgically treated for L4-5 DS
between 1 January, 2009 and 31 December, 2010 was analysed and compared to outcomes
reported in the Spine Patient Outcomes Research Trial (SPORT).
Results: Of 1444 surgical cases, 97 (6.7%) had the diagnosis of DS, and of these, no
complications were seen in 49.5%. The total intra- (10.3%) and post-operative (73.2%)
complication rate was 83.5%, suggesting that some of the 50.5% of patients with complications
had more than one AE each. The most common intra-op AEs were bone/hardware issues
7.9%, and dural tears 6.5%. The most common postoperative AEs were UTI 14%, delirium
6.5%, surgical site infection 5.2%, and neuropathic pain 5.2%. SPORT reported substantially
lower complication rates: an adverse-event-free rate of 87% intra-operatively and 69% postoperatively, with total complication rates at four years of follow-up of 13% each intra- and postoperatively.
Conclusion: This prospective analysis highlights a notable discrepancy in AE rates compared
to published literature not specifically designed to look at AEs. Further distillation of this data
may demonstrate diagnosis-specific correlations with specific types of adverse events.
186: Radiostereometric Analysis (RSA) Evaluation of One-level Lumbar Fusions Using
Trabecular Metal Intervertebral Cages Over Two years
William Oxner, NS; Elise Laende, NS; Allan Hennigar, NS; James Edwards, NS; Michael J
Dunbar, NS
Purpose: Quantitative assessment of the success of spinal fusion remains a significant
challenge for orthopaedic surgeons. Radiostereometric analysis (RSA) can detect the
presence or absence of mobility between fused intervertebral segments with a high degree of
precision. The purpose of this study was to determine the success of a posterior lumbar
interbody fusion using Trabecular Metal™ Cages (Zimmer Spine, Minneapolis MN) augmented
with pedicle screw instrumentation with RSA.
Method: Eighteen patients were recruited using strict inclusion criteria. During surgery, six
tantalum markers, 0.8mm in diameter, were inserted into the two vertebrae at the fused level.
Using a calibration box, stereo RSA radiographs were taken within four days post-operatively
and then at follow-up exams at six weeks and three, six, 12 and 24 months following surgery.
At the follow-up exams RSA radiographs were taken with patients first in a supine position and
then in a sitting position to determine the movement between the fused segments at each time
point.
Results: Fusion assessment shows relative motion between the two vertebrae, with average
total motion of 0.57 mm, 0.94 mm, 0.68 mm, 0.52 mm, and 0.65 mm at six weeks, three
months, six months, 12 months, and 24 months respectively when comparing supine to seated
positions of patients. The precision of the RSA method for this application was assessed from
double RSA clinical exams of all subjects and found to be 0.11 mm for total motion.
Conclusion: The leveling off of the relative motion between the fused segments after three
months suggests successful fusion has been achieved with the Trabecular Metal™ Cages
augmented with pedicle screw instrumentation. While RSA analysis is challenging, the
resolution achievable makes RSA a superior measurement method to conventional
radiography for assessing spinal fusions.
187: Traditional Open versus Minimally Invasive Decompression and Fusion of the
Lumbar Spine: A Retrospective Analysis
Neil Manson, NB; Melissa McKeon, NB; Edward Abraham, NB; Renee Elliott, NB
Purpose: Minimally invasive surgical (MIS) techniques offer theoretical advantages over
traditional midline (OPEN) techniques for lumbar decompression and fusion procedures. These
advantages have yet to be adequately substantiated in the literature via direct comparison.
Therefore the purpose of the study is to identify advantages and pitfalls of MIS versus OPEN
techniques in the management of lumbar degenerative pathologies via decompression and
fusion.
Method: Retrospective review of a prospective database from September 2006 to November
2009 identified 187 patients receiving single level lumbar decompression and fusion
procedures. Of the 187, 141 (OPEN = 90, MIS = 51) met the inclusion criteria and were
included in the analysis. Pre-operative (i.e. patient demographics, disability and pain scores),
intra-operative (i.e. blood loss, surgical time, complications), and post-operative (i.e.
complications, revision rates, disability and pain scores) data were analyzed using an ANOVA
(p > 0.05) to detect significant differences between groups.
Results: Both surgical groups demonstrated statistically similar preoperative demographics
(age, gender, BMI, ODI, VAS Leg and Back). The OPEN procedure demonstrated statistically
greater blood loss before (519.6 vs. 259.4ml) and after (377.5 vs. 232.2ml) Cell Saver blood
return with significantly shorter operative time (124.1 vs. 194.4min). Otherwise, all other
measures were similar. Intra-operative and post-operative complications, hospital stay, and
revision rates were equal. At one year follow-up, both groups displayed a similar drop in ODI
(OPEN: 50.7 to 29.3%, MIS: 55.7 to 39.6%), VAS Leg (OPEN: 7.4 to 4.3, MIS: 7.3 to 4.1), and
VAS Back (OPEN: 7.8 to 3.6, MIS: 7.5 to 4.5).
Conclusion: Specific surgical approach techniques may offer certain advantages to optimize
outcomes. Ultimately, appropriate technique at the level of the spine to provide decompression
and stabilization should ultimately dictate surgical success. Future work should focus on
preoperative decision making, operative challenges, and objective biomechanical measures to
assure similarity between techniques.
188: Wiltse versus Midline Approach for Fusion of the Lumbar Spine: A Prospective
Cohort Comparison
Zhi Wang, BC; Christian DiPaola, BC; Charles Fisher, BC; John T Street, BC
Purpose: The Wiltse bilateral muscle splitting approach represents an alternative to traditional
midline approach to the lumbar spine for decompression and fusion of degenerative
conditions. When comparing Wiltse to midline approaches our primary null hypothesis was that
there is no difference in rates of surgical site infection (SSI). The secondary null hypothesis
was that there would be no difference in the rates of secondary surgery within .
Method: Between July 2005 and June 2008 we identified 183 Wiltse cases and 53 midline
cases of single or two level lumbar fusion, matched for age, gender, co-morbidities, number of
levels fused and history of previous surgery. There was a minimum of 3 year follow-up and
statistical analysis was performed using Fishers exact test and one sided p values.
Results: Mean age (p=0.02), length of hospital stay( p=0.008) and intra-operative blood loss
(p<0.001) were significantly lower in the Wiltse group. There was no difference in the mean
length of the surgical procedure(p=0.689). In the Wiltse group there was a greater use of bone
graft alternatives, in particular BMP (p=0.005). The rate of SSI was 1.9% Wiltse versus 7.5%
Midline (p=0.11). The rate of second surgery within 3 years was higher in the Midline group
(p=0.025). Delayed wound complication (23 vs 0%) and adjacent segment failure (10% vs 0%)
higher in the Midline group, while pseudarthrosis was higher in the Wiltse group (25% vs 7%).
Conclusion: The Wiltse approach is a viable alternative for 1 or 2 level lumbar arthrodesis
with lower rates of SSI and lower blood loss. Secondary surgery for junctional failure is less
common, but pseudarthrosis is more common.
189: A Biomechanical Evaluation of the Dynamic Sling Effect of the Latarjet Procedure:
Does It Improve Shoulder Stability?
Joshua Giles, ON; Harm W Boons, NL; Kenneth Faber, ON; Ilia Elkinson, NZ; Louis Ferreira,
ON; James Johnson, ON; George S Athwal, ON
Purpose: The conjoint tendon, transferred during the Latarjet procedure, is thought to provide
a stabilizing sling effect; however, the significance of this mechanism is unknown. The purpose
of this in-vitro biomechanical study was to evaluate the effects of the Latarjet procedure, with
and without conjoint tendon loading, on stability and range of motion (ROM).
Method: Cadaveric shoulders (n=8; avg. age: 78 yrs) were tested on a custom simulator
capable of loading eight muscle groups. All testing conditions (intact, 30% anterior glenoid
defect, and Latarjet with and without conjoint loading) were performed on each specimen as
repeated measures. Each condition was tested in two levels of elevation (0 and 90°) with
conjoint loading (0 and 10N) randomized. Passive internal/external rotation ROM, joint
dislocation, and shoulder stiffness were evaluated. Joint stiffness was tested in neutral and
60o of external rotation using an anterior 70N load. Humeral internal/external rotation ROM
was determined using a predefined applied torque.
Results: All 30% glenoid defects caused dislocation in abduction and external rotation. The
loaded Latarjet prevented dislocation in all specimens, while the unloaded stabilized 6 of 8. In
abduction external rotation, there were no significant differences in stiffness between loading
states (p=0.176); however, the unloaded Latarjet did trend towards a decreased stiffness as
compared to intact (p=0.081). In adduction, there were no significant differences in stiffness
between intact and the loaded Latarjet (p≥0.228); however, in neutral rotation the unloaded
Latarjet (p=0.015) and the 30% defect (p=0.011) had significantly less stiffness than intact, and
were nearly equal. No differences were found in ROM in adduction; however, in abduction the
loaded Latarjet significantly reduced ROM compared to unloaded (29.03±15.16, p=0.014).
Conclusion: A dynamic sling effect of the conjoint tendon is thought to enhance stabilization.
This study found that the loaded Latarjet prevented dislocation in 25% more cases than
unloaded and thus can be said to influence joint kinematics. The unloaded Latarjet had
minimal effect on stiffness, especially in neutral rotation where it was essentially equal to the
30% defect and significantly less than intact. In contrast, the loaded Latarjet increased joint
stiffness; however, the increase was not statistically greater than unloaded. An important
observation from this data is that stiffness improved during loaded external rotation due to
increased conjoint wrapping around the humeral head. Conjoint loading caused significant
restriction in ROM compared to the 30% defect and unloaded but not compared to loaded
intact indicating that the sling effect is unlikely to limit motion beyond the physiologic level.
These findings indicate that glenohumeral stability is improved by conjoint tendon loading, thus
supporting the importance of the sling effect. Stability parameters, however, are not fully
restored to the intact level.
190: An In-Vitro Biomechanical Comparison of the Classic and Congruent Arc Latarjet
Procedures
Joshua Giles, ON; Harm Boons, NL; Ilia Elkinson, NZ; Kenneth Faber, ON; Louis Ferreira,
ON; James Johnson, ON; George S Athwal, ON
Purpose: The Latarjet procedure is an effective treatment for complex anterior shoulder
instability and has two variants. The Classic Latarjet transfers the coracoid directly to the
anterior glenoid while the Congruent Arc rotates the coracoid 90° so that its undersurface is
flush with the glenoid. The purpose of this in-vitro biomechanical study was to compare the
range-of-motion (ROM) and stability of these two techniques.
Method: Eight cadaveric forequarters were mounted on a custom simulator that applies loads
independently to eight muscle groups including the conjoint tendon. Repeated measures were
used to evaluate test conditions of intact, 30% glenoid defect, and Classic and Congruent
variants. Outcome measures of internal/external ROM, joint stiffness, dislocation, and
translation were evaluated in 0o and 90o combined abduction. Stiffness was tested in neutral
and 60o external rotation using an anterior 70N load. ROM was determined using a predefined
clinical torque.
Results: Stiffness in abduction external rotation was significantly reduced in the defect as
compared to intact (21.9±13.0N/mm, p=0.012), Congruent (7.0±4.2N/mm, p=0.015), and
Classic (7.3±1.4N/mm, p<0.001) conditions. In all test positions, intact was not significantly
different from the two variants, and they did not significantly differ from each other (p≥0.102).
All specimens dislocated with a defect in abducted neutral and external rotation. The Classic
variant resulted in 1 specimen dislocating in abduction neutral rotation, and 0 in external
rotation. The Congruent variant effectively prevented dislocation in all positions. In adduction,
no significant differences in ROM were observed (p>0.05). In abduction, ROM was significantly
reduced after Classic and Congruent transfers as compared to the defect (25.8±18.0°,
p=0.032; 22.2±16.7°, p=0.041) but did not differed from intact or each other (p≥0.282). The
Congruent technique in abduction external rotation was the only configuration to produce
significantly greater translation than the Classic technique (3.5±2.9mm, p=0.013).
Conclusion: The Classic Latarjet procedure is clinically proven; however, the introduction of
the Congruent Arc variant has necessitated evaluation of the comparative effects of the two. It
was found that both techniques achieved a significant increase in joint stiffness in the critical
position of clinical apprehension (abduction external rotation) but neither repair produced a
significantly greater effect. Both techniques were able to eliminate dislocation in all cases
except for one treated with the Classic; however, notably, the Congruent variant allowed
significantly greater translations due to the increase in glenoid width. ROM data confirmed that
neither variant caused significant changes in motion compared to intact; however, both did
restrict motion compared to the 30% defect, confirming the Latarjet’s stabilizing effects.
Therefore, the two Latarjet techniques do not significantly differ from each other in the
parameters tested.
191: Bristow Procedure for Anterior Shouder Instability- Bone Block or Tension-band
Effect ? A Cadaveric Study
Maxime Côté, QC; Stéphane Pelet, QC; Réjean Cloutier, QC; Marie-Pier Beaulieu, QC
Purpose: Anterior shoulder dislocation can lead to instability in up to 35% of patients and
surgical treatment is then recognized. Bristow procedure was described in 1950 and
demonstrates good clinical results on stability. Bristow's efficacy is based on two hypothetical
mechanisms (not yet demonstrated), either 1) Bone block (coracoid process) or 2) Tension
band (conjoined tendons or subscapularis). The goal of this study is to demonstrate the
individual role of each mechanism. The hypothesis states that only the bone block is
responsible for the stability of this procedure.
Method: 8 fresh-frozen cadavers (16 shoulders) were operated in the Laboratoire d'Anatomie
at Laval University in Quebec by the same shoulder surgeon. For each shoulder, through a
deltopectotal approach, a soft-tissue Bankart lesion was realised and instability confirmed with
fluoroscopy. A Bristow procedure was realised according to the original descritpion: tip of
coracoid process with conjoined tendons inserted at the front of the glenoid-anteroinferior
aspect- through a longitudinal window in the inferior aspect of the subscapularis. The head
displacement/glenoid length ratio (HD/GL) was measured on an axillary view at three times: 1)
Before Bristow procedure 2) After Bristow procedure 3) After cutting the conjoined tendons
from the coracoid process. The force applied was constant during all the procedure.
Descriptive statistical analysis with Fisher exact test was done.
Results: Bristow procedure is efficient on stability with a significantly lower HD/GL ratio from
30% (95%CI:25-35;p<0,05). After cutting the conjoined tendons, 93.8% of shoulders
demonstrated no modification of the HD/GL ratio (p<0,05). This proves that Bristow procedure
is effective only through a bone block mechanism.
Conclusion: This cadaveric study is the first study at our knowledge that tried to demonstrate
the real mechanism of stability with the Bristow procedure. We demonstrated that the main
effect is confered through a bone block mechanism and that the role of the conjoined tendons
or subscapularis muscle is not relevant on the stability after this procedure. These results fit
with other published studies demonstrating the absence of EMG activity in patients with
Bristow procedure. Even if this study is limited through its cadaveric design, the great number
of fresh-frozen cadavers and the limitation of bias allow to state significant comclusion. The
Bristow procedure is effective only through a bone block mechanism.
192: Coracoid Process Autograft Incorporation Following Latarjet Transfer for Anterior
Shoulder Instability
Danny P Goel, BC; James R Romanowski, US; Jon JP Warner, US
Purpose: Advanced glenoid bone loss or recurrent shoulder dislocation following soft tissue
procedures for anterior shoulder instability often require osseous reconstruction. For patients
undergoing a Latarjet procedure, successful incorporation of the transferred bone is
considered a critical element for reestablishing shoulder stability. Traditional clinical measures
of a healed bone graft are based on symptoms of pain, stability, and radiographic parameters.
Osseous union as evaluated by CT scans has not been reported in the literature.
Method: Fifty-one consecutive patients (Age 16-68 yo; avg: 36 yo) undergoing a coracoid
process transfer for large glenoid defects or recurrent shoulder instability following failed soft
tissue procedures were identified. A retrospective review found twenty-six patients (twentyeight shoulders) having postoperative CT scans available within a single institution. Six
patients (23%) were female and twenty were male (77%). Surgical procedures were performed
between 2005-2009 by a single surgeon. The CT scans were obtained 2.5-37 months (avg. 6.9
± months) after surgery and were reviewed by two fellowship trained shoulder surgeons for
bony union of coracoid process to the native glenoid.
Results: : For patients with CT scans performed ≥6 months after surgery (10 shoulders), only
1 glenoid (10%) failed to show signs of cortical bridging. Bony union was found in 90% (9/10)
of patients. There was a statistical significance between union and lack of union for shoulders
>6 months postop (p=0.021). For patients with CT scans performed 4 – 5.9 months after
surgery (15 shoulders), six glenoids (40%) did not display cortical bridging. Nine shoulders
(60%) displayed coracoid union to the glenoid during this interval. There was no statistical
significance within this interval (p=0.607). For patients with CT scans performed from 2 - 3.9
months postoperatively (3 shoulders), two glenoids (67%) failed to show evidence of cortical
bridging between the coracoid and glenoid (p=1.00). One shoulder (33%) showed bony union.
When comparing 2-5.9 months with >6 months, there was a statistically significant decrease in
lack of union (p=0.039). When comparing union rates between intervals, statistical significance
was found between 2-3.9 months and 4-5.9 months (p=0.021) and between 2-3.9 months and
6+ months (p=0.021). The interrater reliability was found to be Kappa = 0.916 (p<0.001), 95%
CI (0.753, 1.079). One shoulder (4%) demonstrated graft osteolysis.
Conclusion: Coracoid process transfer results in reliable union demonstrated on CT scans in
90% of patients when studied greater than 6 months from the time of surgery. Reliable
osseous integration was found to be less evident during early follow up (< 6 months).
Increasing rates of bony incorporation were evident with advanced time from the date of
surgery and this study suggests that CT scan radiographic evaluation of bony union should be
delayed >6 months to optimize recognition of osseous fusion.
193: Could Posterior Capsule Tightness be a Contributor to Anterior Shoulder
Instability?
Ryan T Bicknell, ON; Gabriel Venne, ON; Sima Zakani, ON; Erin Janine Smith, ON; Brian
Rasquinha, ON; Randy E Ellis, ON
Purpose: Anterior shoulder instability is a common injury observed in young athletes, such as
throwing athletes, who perform repetitive overhand movement accompanied by forceful followthrough. Most cases typically respond well to physiotherapy, however chronic instability may
require surgical intervention. Surgical treatments are aimed at tightening the anterior capsule,
implying that the instability is caused by abnormal anterior laxity; yet, there are still cases
which fail to improve following tightening. Our hypothesis is that anterior instability may be due
to capsular imbalance, particularly posterior capsular tightness even in the absence of anterior
laxity. The objective is to investigate the effect of posterior capsule tightness on anterior
translation of the humeral head.
Method: Four in-vitro trials were performed using cadaver shoulders consisting of a complete
scapula, entire upper limb, and intact rotator cuff. Three specimens were fixed while one was
fresh-frozen. The scapula and humerus were instrumented with opto-electronic motion capture
equipment so that precise position information could be recorded for analysis. Each shoulder
was moved passively through a series of 14 movements comprising various combinations of
abduction/adduction, flexion/extension, internal/external rotations and anterior/posterior
movements. The entire movement series was repeated for 5 different soft tissue states: rotator
cuff intact, rotator cuff removed (capsule intact), and induced posterior capsular plications of
5mm, 10mm and 15mm. The maximum anterior translation of the humerus was computed for
each movement in each soft tissue state.
Results: There was significantly higher anterior translations observed in the fresh-frozen
compared to the fixed specimens. The mean maximum anterior translation was 14.2mm.
Maximum anterior translation was observed primarily in motions involving abduction/adduction
with internal rotation, and abduction with external rotation, i.e. common throwing motions. No
significant difference in anterior translation was found with removal of the rotator cuff intact
(p>0.05). No significant difference was found at 15mm of induced tightening (p>0.05), while
anterior translation was significantly higher with 5mm and10 mm of tightening (p<0.05).
Conclusion: This study suggests that posterior capsule tightness contributes to anterior
motion of the humeral head and may be a factor in anterior instability. The implications of these
findings may advocate posterior capsule stretching physiotherapy or a posterior capsular
surgical release as potential treatment therapies for anterior instability.
194: Does Subacromial Cortisone Injection Influence the Outcome of Non-Operative
Treatment for Chronic Full-Thickness Rotator Cuff Tears?
Richard Boorman, AB; Kristie D More, AB; Kelly Brett, AB; Robert M Hollinshead, AB; Ian KY
Lo, AB; Preston Wiley, AB
Purpose: A comprehensive non-operative treatment program for patients with chronic fullthickness rotator cuff tears has been developed and studied at our clinic. The program consists
of many different treatment modalities including physical therapy, graduated home based
exercises, cortisone injections, anti-inflammatory medications, and activity modification. Our
objective was to determine if subacromial cortisone injection influenced the outcome of the
comprehensive, non-operative treatment program for patients with chronic full-thickness rotator
cuff tears.
Method: One hundred patients were enrolled in a prospective, non-operative rotator cuff study
at a tertiary based referral center. Patients were seen by a sport medicine physician at
baseline and 6 weeks; by a physical therapist at baseline and at two-to-four weeks; and by a
sub-specialized shoulder surgeon at 3 months. All patients underwent a home based program
of stretching and strengthening exercises taught to them by the physical therapist. Adjunct
treatments such as cortisone were prescribed at the discretion of the treating sport medicine
physician at baseline or 6 weeks, or by the surgeon at 3 months. Patients were defined as
“successful” or “failed” at the three month appointment by the surgeon. Successful patients
had improved to the point that surgery was no longer an appropriate treatment option, whereas
failed patients consented for surgery. The number of patients who had a cortisone injection
during the three month course of the study was evaluated to determine if cortisone influenced
outcome.
Results: Overall, 75 out of 100 patients (75%) were successful, while 25/100 (25%) failed the
non-operative treatment program. In total, 31 patients (31%) had a cortisone injection, while 69
(69%) did not. Of those that had a cortisone injection, 19 (61%) went on to be successful with
the non-operative treatment program, while 12 (39%) failed the non-operative program. Of the
total number of successful patients 19/75 (25.3%) had a cortisone injection. Of the total
number of failed patients 12/25 (48%) had a cortisone injection. Chi-square analysis examining
the influence of cortisone on overall outcome shows a significant difference between groups (p
= 0.03).
Conclusion: Cortisone was used significantly more frequently in patients who ultimately still
failed the comprehensive non-operative treatment program, despite the fact that 61% of
patients who received a cortisone injection had a successful outcome.
195: Injury to the Suprascapular Nerve During Arthroscopic Superior Labral Repair
Martin J Bouliane, AB; Lauren Beaupre, AB; Nigel Ashworth, AB; Robert Glasgow, AB;
Jeffery Bury, AB; Robert Lambert, AB; Anelise Silveira, AB; David M Sheps, AB
Purpose: A recent cadaveric shoulder study has reported that standard techniques for
arthoscopic superior labral repair can put the suprascapular nerve at risk due to drill and
anchor perforation of the medial glenoid wall. The purpose of this study is to prospectively
evaluate the clinical risk of suprascapular nerve injury during arthroscopic superior labral repair
in smaller patients as this population appears to be at particular risk for medial wall perforation.
Method: Between March 2008-April 2011, 12 patients under a height of 178 cm undergoing
arthroscopic superior labral repair were prospectively enrolled. Intra-operative data collection
included portal location, labral tear characteristics, number, location and type of anchors, and
surgeon impression of the presence or absence of medial glenoid wall perforation. Nerve
conduction studies were obtained post-operatively to assess suprascapular nerve function. A
post-operative Magnetic Resonance Image (MRI) was performed and read by a trained
musculoskeletal radiologist to document perforation of the medial glenoid wall and the distance
from the anchor to the suprascapular neurovascular bundle. DASH scores were recorded pre
and 6 months post-operatively.
Results: Medial wall perforation by suture anchors occurred in five of 12 patients (42%), with
four patients having a single perforation and one patient having two perforations. Eight of 38
(21%) anchors drilled into the superior half of the glenoid perforated the medial wall while six of
20 (30%) anchors inserted into the postero-superior quadrant of the glenoid perforated the
medial wall. Perforations occurred through both the portal of Wilmington and the anterosuperior portal. The distance to the suprascapular neurovascular bundle from the perforating
anchors ranged from 0-4 mm. Nerve conduction studies revealed subclinical signs of an
incomplete nerve injury in one patient. DASH scores improved an average of 30 points in
these patients.
Conclusion: Using standard arthroscopic techniques to repair the superior labrum, medial wall
perforation by suture anchors is common in smaller patients. Further, the suprascapular nerve
can be injured if perforation occurs.
196: Latissimus Dorsi Tendon Transfer for Massive Rotator Cuff Tears: A Cadaveric
Study
Patrick D G Henry, ON; Timothy Dwyer, ON; Michael D McKee, ON
Purpose: The latissimus dorsi tendon transfer (LDTT) for the treatment of massiver rotator cuff
tears is a technically difficult procedure. Releasing the tendon insertion can be hazardous as
several vital neurovascular structures are near to the dissection plane. A second critical step
involves obtaining adequate length, which involves extensively releasing the muscle belly from
its local soft–tissue attachments. We performed a cadaveric study with twelve shoulders to
further delineate the anatomic features of the latissimus dorsi muscle to enhance the safety
and efficacy of transfer.
Method: Twelve shoulders embalmed with a modified Thiele method were obtained. A
deltopectoral dissection allowed visualization of the lat dorsi tendon insertion. Using a
calibrated digital ruler, measurements were made from the superior and inferior tendon edges
to the axillary nerve, radial nerve, brachial artery, profundus brachialis artery, and posterior
circumflex artery. Measurements were performed with the arm at the side, and in the forwardflexed/internally-rotated position. A standard LDTT surgery was then performed. With the
transferred tendon under a standardized tension of 2 lbs, sequential measurements from the
tendon edge to a reference point on the humeral head were made to assess the effect of two
lengthening procedures: The standard release (involving a 10 cm posterior skin incision), and
an extensile release (25 cm incision).
Results: With the shoulder forward flexed/internally rotated (surgical position), the distance
from the superior tendon edge to the radial nerve, brachial artery, axillary nerve, and posterior
circumflex artery were measured to be 30mm, 28mm, 21mm, and 15 mm respectively. The
distance from the inferior tendon edge to the radial nerve, brachial artery, and profunda
brachialis artery were measured at 17mm, 22mm, and 14mm respectively. Moving the arm
from a flexed/internally-rotated position to neutral decreased these distances , which was
statistically significant in 3 of the 6 measurements. When performing the release procedures,
an average of 15mm of length (range: 8 to 21mm) was gained from a standard release, and an
additional 17mm (range: 10 to 38mm) was gained with an extensile release. In no specimens
did the neurovascular pedicle limit the transfer through a tethering effect.
Conclusion: Cadaver tissue demonstrates consistently measureable safe distances from the
tendon edge to the vital neurovascular structures during the tendon release portion of
latissimus dorsi tendon transfer surgery. These distances are increased by forward flexing and
internally rotating the shoulder, and can be used as a guide during tendon release through the
posterior approach. The standard muscular release provides an average of 15mm of length to
the musculotendinous unit, and an additional 17mm can be gained by performing an extensile
release. The pedicle does not act as a tether to limit the transfer length. These findings can
enhance the safety and efficacy of LDTT surgery.
197: Short Term Complications of the Latarjet Procedure
Danny P Goel, BC; Anup Shah, US; Robert B Butler, US; James R
Laurence D Higgins, US; Jon J P Warner, US
Romanowski, US;
Purpose: While results of Latarjet procedure have been reported previously there is little
written regarding early complications of this procedure. Our purpose was to report our
experience with Latarjet for instability and highlight the initial complications that may occur
following this procedure.
Method: Between January 2005 and January 2010, 47 patients (48 shoulders) underwent the
Latarjet procedure for anterior shoulder instability. All patients had some element of anterior
glenoid rim bony deficiency or failed prior soft-tissue Bankart repair. Minimum follow up was 7
months.
Results: 43 patients were available for follow-up. The overall complication rate was 25%
(12/48). Complications were divided into three groups: infections, instability, and neurologic
injury. We identified three patients (3/48, 6%) who developed a superficial infection that
resolved following irrigation and debridement and administration of antibiotics for three to four
weeks. Four patients (4/48, 8%) developed recurrent instability. Two patients failed within a
year and the other two failed at 19 and 42 months postoperatively. Five patients (5/48, 10%)
were identified who had neurological injury. Of these, two involved the musculocutaneous
nerve, one involved the radial nerve, and two involved the axillary nerve. The three patients
with musculocutaneous and radial nerve injuries were sensory neuropraxias that fully
recovered within two months. The two with axillary nerve dysfunction have persistent sensory
disturbances and one patient has residual weakness that has not yet recovered fully.
Conclusion: An overall complication rate of 25% (12/48) is higher than reported in the
literature. While most of these completely resolved, several patients have residual neurologic
symptoms. Patients should be made aware of the risk for complication with this procedure
though most will be temporary problems.
198: The Biomechanical Strength of Classic and Congruent Arc Latarjet Constructs
Joshua Giles, ON; Gabor Puskas, CH; Mark Welsh, ON; George S Athwal, ON; James A
Johnson, ON
Purpose: The Classic and the Congruent Arc Latarjet are two techniques of coracoid transfer
which differ only in graft orientation. The Classic method orients the lateral coracoid surface
flush with the glenoid, while the Congruent method does so with the inferior surface. However,
the biomechanical parameters of these two reconstructions are unknown. Hence, the objective
of this study was to compare these two constructs by quantifying load transfer and graft
displacement.
Method: Eight shoulders (four pairs) were tested using a materials testing machine.
Specimens were tested in their intact condition and following paired randomized Classic or
Congruent Latarjet reconstruction of a 25% anterior glenoid bone defect. The glenoid rim was
subjected to 100 cycle sets (50, 100, 150 and 200N at 1Hz) of loading using the humerus
oriented in 30° of abduction and with the force oriented 30° anterior. Subsequently, load was
increased until graft failure (10mm displacement). Biomechanical outcome parameters of
strain, recorded at the anterior glenoid vault, used to assess load transfer, and displacement
used to assess stability were quantified.
Results: Above 150N the Congruent Arc produced a significant increase in humeral
displacement compared to intact (>3.8mm, p≤0.045). In contrast, the Classic Latarjet produced
no significant differences in displacement at any load (p≥0.278). The Classic Latarjet allowed
significantly less displacement than the Congruent above 150N (>3.2, p≤0.033). A significant
difference (p=0.031) in failure load was recorded (Classic: 701.1±83.4N, Congruent:
435.9±166.9N). Strain significantly increased during 100N loading with the Congruent Arc
compared to intact (251±142µε, p=0.038). There were no differences in strain when comparing
the reconstructions (p≥0.176), intact shoulder pairs (p≥0.148), or intact shoulders and their
subsequent Classic Latarjet reconstructions (p≥0.246).
Conclusion: In addition to the Latarjet’s stabilizing effects, it is also important to understand
the construct strength and resulting load transfer. We found that the Classic Latarjet produced
displacements similar to intact and thus possesses sufficient strength to maintain native
humeral head kinematics. Conversely, above 150N the Congruent technique produced
significantly larger displacements than the Classic and the ultimate failure load was
significantly inferior. The Classic Latarjet effectively reestablished intact load transfer as no
differences in strain were observed; however, the Congruent Arc did alter load transfer
patterns but only significantly at one loading level. This alteration was expected as the
orientation of the coracoid in the Congruent technique widens the glenoid greater than the 25%
defect created. This discrepancy in glenoid width may also lead to abnormal kinematics. The
differences observed in graft displacement and glenoid strain demonstrate a substantial
variance in strength between the Classic and Congruent Arc constructs.
199: Assessment of the Incremental Cost-utility of Surgery Compared to Failed Medical
Management for the Treatment of Hip, Knee and Spine Osteoarthritis
Raja Rampersaud, ON; Peggy Tso, ON; Kevin Walker, ON; Brendan Eagen, ON; Nizar
Mahomed, ON; Peter C Coyte, ON
Purpose: The demand for surgery for osteoarthritis (OA) of the hip, knee, and spine continues
to rise. While total hip arthroplasty (THA) and total knee arthroplasty (TKA) have been widely
accepted as cost-effective procedures, the cost-effectiveness of spine surgery –
decompression (D) and decompression with fusion (DF) – for the treatment of degenerative
conditions remain controversial. The primary purpose of this study was to directly assess and
compare of the cost-effectiveness of end-stage surgical treatment of hip, knee and spine (onetwo level-focal spinal stenosis with or without spondylolisthesis) osteoarthritis.
Method: An incremental cost-utility ratio (ICUR) analysis comparing D and DF to THA and
TKA, the perspective of the provincial health insurance system was based on outcomes from a
prospective observational matched-cohort study and retrospectively collected costs. Patient
outcomes were measured using SF-6D utility scores derived from the short-form (SF) 36 over
a five-year follow-up period. Utility, abased on five-year data was modeled over the lifetime and
quality-adjusted-life-years (QALY) were determined. Surgical cost included total hospital, inpatient rehabilitation, and revision cost for each cohort over five years. The primary outcome
measure, incremental cost per QALY gained, was calculated by estimating mean incremental
costs and QALYs of surgery compared to failed medical management of each diagnosis group
after discounting costs and QALYs at 3%. Sensitivity analyses were conducted to determine
factors affecting the value of each type of surgery.
Results: The lifetime ICUR was $4,091/QALY for THA, $5,038/QALY for TKA, and
$3,530/QALY for combined spine surgery groups (DF = $7,444/QALY and D = $2,261/QALY).
Values are based on life expectancies of 20.4, 19.1 and 19.6 years for hip, knee and spine
patients respectively. The sensitivity analyses (variations of outcome, cost, and revision rate)
did not alter the ranking of the lifetime ICURs.
Conclusion: Compared to failed medical management, surgery for hip, knee and spine
osteoarthritis is cost-effective. Furthermore, the ICUR of surgery for focal spinal stenosis with
or without degenerative spondylolisthesis (D+DF) was comparable to that of THA and TKA.
200: Drug Release and Bone Growth Studies of Antimicrobial Peptide-loaded Calcium
Phosphate Coating on Titanium Implants
Bas A Masri, BC; Mehdi Kazemzadeh-Narbat, BC; Shahryar Noordin, BC; Donald S Garbuz,
BC; Clive P Duncan, BC; Robert EW Hancock, BC; Rizhi Wang, BC
Purpose: Preventing infection is a major challenge in total joint arthroplasty. There are few
reports on in-vivo bone growth on antimicrobial peptide-loaded orthopaedic implants.
Antimicrobial peptides (AMP) are well recognized as promising novel agents against multi-drug
resistant pathogens. This work investigated the in-vitro drug release, antimicrobial
performance, and cytotoxicity, as well as the in-vivo bone ingrowth of an antimicrobial peptide
(AMP) loaded into calcium phosphate (CaP) coated Titanium (Ti) implants, in a rabbit model.
Method: Two potent AMP candidates (HHC36: KRWWKWWRR), and (Tet213:
KRWWKWWRRC) were first investigated through an in-vitro cytotoxicity assay. MTT (3-(4,5dimetyl-2-tiazolyl)-2,5-diphenyl-2H-tetrazolium bromide) absorbance values revealed that
HHC36 showed much lower cytotoxicity (200 µg/mL) than Tet213 (50 µg/mL). The in-vivo
rabbit study utilized 25 adult New Zealand white female rabbits, randomly distributed to three
groups of implants, Ti (5 rabbits), CaP (10 rabbits), and CaP-AMP (10 rabbits). Each rabbit
received two identical implants, one in each femur. Surgery was performed under sterile
conditions and general anesthesia. Animal study protocol was approved by the Animal Care
Committee at the University of British Columbia.
Results: The CaP-AMP coatings were antimicrobial against Staphylococcus aureus and
Pseudomonas aeruginosa strains in colony-forming units (CFU) assays. The AMP HHC36
loaded onto CaP had a burst release during early hours followed by a slow and steady release
for seven days as measured using UV/Vis (Ultraviolet-Visible) spectroscopy. No cytotoxicity
was observed on CaP-AMP samples against MG-63 osteoblast-like cells after five days. In a
trabecular bone growth study using cylindrical implants, loading of AMP HHC36 did not impair
bone growth onto the implants. Significant bone on-growth was observed on CaP-coated Ti
with or without HHC36 loading, as compared with Ti alone.
Conclusion: The AMP-CaP coating thus offers antimicrobial and osteoconductive properties
to orthopaedic implants. This coating can significantly kill S. aureus and P. aeruginosa bacteria
while being non-cytotoxic to MG-63 osteoblast like cells. The in-vivo bone on-growth on CaPAMP was observed to be extensive in comparison to controls. The calcium phosphate coating
and the simplicity of AMP loading will be the advantages of this antimicrobial coating.
201: Factors that Impact the Choice to Undergo Surgery (FICUS): Enabling Improved
Patient Decision Aids
Raja Rampersaud, ON; Rajiv Gandhi, ON; Anthony Perruccio, ON; Arthritis Program UHN,
ON
Purpose: In orthopaedics, willingness to undergo surgery is often a preference-sensitive
decision. The factors that influence patient willingness however, are poorly understood. Hence
current orthopaedic patient decision aids may be inadequate. We sought to identify patient
characteristics associated with unwillingness to undergo surgery if offered, and to evaluate
whether the influence of some characteristics may be explained by perceptions of surgical risk
and expectations of success.
Method: Immediately prior to surgical consultation for degenerative spine, hip/ knee (H/K),
shoulder/elbow (S/E), or foot/ankle (F/A) conditions, patients completed a survey that
ascertained willingness (unwilling/unsure/willing) to have surgery (primary outcome of interest),
captured demographic and socioeconomic characteristics, and assessed overall physical and
mental
well-being
(SF-36)
and
patient
expectations
of
surgical
success
(unsuccessful/unsure/successful) and perceptions of risk (risky/not risky/unsure). Sequential
multinomial logistic regression models were evaluated. First, patient characteristics were
examined as predictors of perception of risk and expectation of success. Then, all
characteristics (including risk and success) were evaluated as predictors of willingness.
Results: Two-thousand patients completed the survey with valid data from 1,954 patients:
51% were male and 454 (23%) were evaluated for a spine condition, 767 (39%) for H/K, 384
(20%) for S/E, and 349 (18%) for F/A. Overall, 20% of patients reported unwillingness or
uncertainty about surgery and 50% reported being ‘unsure’ about the risk and success of
surgery. Mean SF-36 subcomponent scores were similar for patients across specialities. From
adjusted analyses, females (Odds Ratio (OR) = 1.3 and 1.6) and individuals consulting for
spine (OR =3.7 and 3.0) and S/E (OR=1.4 and 1.9) (as compared to H/K) were significantly
more likely to report uncertainty regarding risk and success. Individuals of South Asian
ethnicity (OR=5.3) and those consulting for F/A (OR=1.6) also were significantly more likely to
report uncertainty regarding success. Independent predictors of unwillingness to have surgery
were expectations of unsuccessful surgery (OR=26.6), a perception of ‘risky’ surgery
(OR=2.0), increasing age (OR=1.02), female (OR=1.6), ethnicity: Black, South Asian and
Other (OR=4.2, 3.6, and 2.3, respectively (as compared to White)), and increasing levels of
bodily pain (OR=1.02). Having had a previous surgery was associated with a greater likelihood
of ‘willingness’ (OR=0.45). Adjusted for all variables, BMI, education, comorbidities, physical
function and mental well-being were not predictive of willingness.
Conclusion: The determinants of willingness to consider surgery are multifactorial. These
study findings suggest that a number of factors should be considered when developing
orthopaedic consultation patient decision-aids and direct surgeon-patient communication
strategies.
202: Looking Beyond the Clinical Box: The Health Services Impact of Surgical Adverse
Events
Clifford Lin, ON; Raja Rampersaud, ON; Camalene Chrysostoum, ON
Purpose: In the Canadian healthcare system, access to inpatient beds is an ongoing and
escalating problem. For surgical services, cancellation of elective surgery directly impacts
access to care and is an increasing source of frustration to all stakeholders. The primary
purpose of this study was to assess the impact of perioperative adverse events (AEs) on
available hospital bed days.
Method: Preliminary analysis of data from a prospective observational study. Information
regarding patient demographic, diagnosis, procedure, and length of stay is being captured by
dedicated research personnel on all in-patient orthopaedic and spinal surgical procedures at
our institution. Occurrences of AEs are documented and categorized daily using the
OrthoSAVES system. Data from the first 6 months (n=908 patients) was analyzed.
Results: In this period there were 227 AEs (intraoperative and postoperative) in 154 patients
(17%). The most common AEs were urinary tract infection (n=33), durotomy (n=23), delirium
(n=21) and urinary retention (n=17). The majority of adverse events (n=196, 86%) were grade
I-II, those that did not require treatment or required minor treatment but were not likely to
impact patient outcome. There were significantly less Grade III-IV AEs (n=21, 9.7%), those
requiring treatment and are likely to impact patient outcome. Adjusting for age, sex, body mass
index, American Society of Anesthesiologists (ASA) physical status, and procedure type, the
mean length of stay (LOS) was 7.0 days (95% confidence interval (CI):5.9-8.1) for patients
without AEs, 11.9 days (CI:10.4-13.4) for grade I-II AEs and 19.9 days (CI:17.2-22.1) for grade
III-IV AEs. Compared to the mean LOS within matched procedure group for patients without
AE, individual patients with grade I-II AEs led to approximately 654 additional days in hospital.
Those with grade III-IV AEs resulted in approximately 373 additional days in hospital.
Conclusion: AEs are responsible for a significant number of additional bed days. The majority
of AEs were of low grade and preventable or modifiable. The development of evidence-based
protocols targeting these “minor” AEs can lead to improved system efficiency.
203: Responding to the Global Injury Burden by Improving Access to Orthopaedic
Medical Devices: A Qualitative Case Study of Orthopaedic Services in Uganda
Maryse Bouchard, ON; Jillian Kohler, ON; James Orbinski, ON; Andrew Howard, ON
Purpose: This study investigates the access of orthopaedic medical devices (OMDs) in
Uganda. The global injury burden is severely underappreciated. Orthopaedic injuries account
for 14% and 9% of the world’s morbidity and mortality, respectively. Ninety percent of injury
deaths occur in low- and middle-income countries. Globally, injuries cause approximately as
many deaths per year as HIV/AIDS, tuberculosis and malaria combined. By the year 2030,
road traffic crashes, a major cause of orthopaedic injury, are predicted to be the third leading
cause of long-term disability globally. Alleviating the burden of orthopaedic injuries will require
timely access to appropriate orthopaedic care and medical devices, such as plaster, an
external fixator or an implant. In many low-income countries however, orthopaedic services
and OMDs are generally inadequate or unavailable, as the required expertise, infrastructure
and funding are often lacking. Despite the negative health impact when OMDs are unavailable,
this is an area that has not been a global health priority and demands immediate attention.
Method: An exploratory qualitative case study consisting of 45 open-ended interviews was
conducted in Uganda in 2010. The interviews explored stakeholders’ experiences in accessing
OMDs in their health care setting. Participants included 16 orthopaedic surgeons, 13 health
care professionals other than orthopaedic surgeons (orthopaedic officers, general surgeons,
medical officers, and nurses), 8 industry representatives, 2 government officials, and 6
patients. Participants were recruited by purposive and snowball sampling. Thematic analysis
was the method used for data analysis.
Results: Analysis of the interview data revealed two broad categories: “Barriers to access of
OMDs” and “Solutions for improving access to orthopaedic care”. Four major themes were
elicited as barriers to OMDs: 1) Poor leadership and corruption in government; 2) inadequate
human resources; 3) inefficient and insufficient healthcare infrastructure; and 4) high costs of
OMDs and poverty. Potential solutions for improving access to orthopaedic care included
policies for prioritization of orthopaedic services, training of more orthopaedic specialists and
incentives for them to work rurally and in the public system, and innovative strategies funding
for orthopaedic services.
Conclusion: Problems of governance, limited human resources, inadequate health care
infrastructure, and high costs of orthopaedic equipment, prevent access to needed OMDs in
Uganda. Without these medical devices, the quality of orthopaedic care suffers and the burden
of preventable injury is exacerbated. Mechanisms to increase access to OMDs and
orthopaedic care globally could include improved transparency in governance, training of more
orthopaedic specialists, policies for prioritization of trauma in health care, and additional
funding for orthopaedic care, including OMDs. Further research into this global health
challenge is needed.
205: Undiagnosed Diabetes Mellitus in Patients Undergoing Elective Total Joint
Replacement
Robert J Feibel, ON; Erin J Keely, ON; Janine C Malcolm, ON; Bob Reid, ON
Purpose: Peri-operative hyperglycemia has been shown to increase the risk of prosthetic
infection. Patients without the diagnosis of diabetes mellitus are at increased risk of developing
deep infection when hyperglycemia occurs following surgery.
Method: Between October 2010 and September 2011, 251 patients undergoing elective total
hip or knee replacement were screened pre-operatively for diabetes mellitus by random blood
glucose and hemoglobin A1C (HgbA1C). Patients with negative screening blood work were
assigned to Group 1 – Diabetes Unlikely. Those with one or both screening tests positive were
assigned to Group 2 – Possible Diabetes. In order to assess the adequacy of a random blood
glucose and HgbA1C as screening tools for the detection of diabetes, 25% of the Group 1
(“diabetes unlikely”) patients were screened with a Glucose Tolerance Test (GTT) at 6 weeks
post-operatively.
Results: There were 230 patients (91.6%) in Group 1 (Diabetes Unlikely) with a mean age of
62.6 years and 17 with possible diabetes in Group 2 (6.8 %, four lost to follow-up, mean age
73.6 years). Ten patients in Group 2 were referred for post-operative follow-up testing with a
GTT: two normal; four pre-diabetic; four positive for diabetes; and 7 GTT pending or lost to
follow-up. Thirty-nine Group 1 patients were screened with a GTT: 28 normal; 11 pre-diabetic.
Hence, 28 % of these ‘normal’ patients were identified as being pre-diabetic or diabetic. All
study patients (Both Group 1 and 2) had a normal screening random blood glucose. Body
Mass Index did not correlate with abnormal blood work or GTT. The only significant difference
was a tendency for Group 2 “Possible Diabetes” patients to be older (p<0.001). The 30-day readmission rate was not statistically different between the groups.
Conclusion: These findings suggest that up to one third of asymptomatic non-diabetic patients
undergoing total joint replacement may be at risk of developing stress-induced post-operative
hyperglycemia or have diabetes and, hence, are at increased risk of developing a prosthetic
infection.
206: Arthroscopic Repair of Massive Rotator Cuff Tears Using a Novel Biceps
Incorporation Technique
Aaron Nauth, ON; Anne-Marie Bedard, BC; Brianne Bentzon, BC; Cheryl Davies, BC; William
D Regan, BC
Purpose: Numerous operative techniques have been described for the treatment of massive
rotator cuff tears where anatomical repair is not possible. However, poor healing and poor
functional outcomes after surgical intervention remain significant problems. We describe the
arthroscopic repair of massive rotator cuff tears in a series of 22 patients, using a novel biceps
incorporation technique. The purpose of the current study was to evaluate the functional and
radiographic outcomes of arthroscopic repair of massive rotator cuff tears using a novel
technique of biceps incorporation.
Method: Between January 2007 and January 2010, twenty-two shoulders with massive rotator
cuff tears, irreparable using standard arthroscopic techniques, underwent repair using a novel
arthroscopic biceps incorporation technique and were included in the analysis. Our technique
involves the liberal use of marginal convergence sutures incorporating the biceps, followed by
anchoring of the converged tendon and biceps to the greater tuberosity using suture anchors.
All patients underwent a standardized assessment at a minimum of one year post-operatively,
including an ultrasound examination to assess for radiographic healing of their tear. The mean
follow-up period was 23 months (range = 12-29).
Results: All 22 patients reported satisfaction with the surgery and willingness to have the
surgery performed again. The mean age-adjusted Constant and American Shoulder and Elbow
Surgeons (ASES) scores post-operatively were 98.8 (range = 47 – 130) and 83.4 (range = 34
– 100), respectively. The mean Western Ontario Rotator Cuff index (WORC) post-operatively
was 76.0% (range = 20.0% – 98.5%). The mean Physical and Mental components of the Short
Form-12 (SF-12) questionnaire were 45.7 (range = 10.0 – 60.4) and 52.1 (range = 28.2 –
63.9), respectively. On the basis of Constant scores, 91% (20/22) of patients had an
excellent/good result. Ultrasound examination showed that 36.4% (8/22) of patients had
radiographic evidence of complete rotator cuff tears post-operatively and that 40.9% (9/22) had
radiographic evidence of partial tears, while the remaining 22.7% (5/22) were judged to be
radiographically intact. Statistical comparison of patients with radiographically intact/partially
intact rotator cuff repairs to those with complete re-tears showed no significant differences.
Conclusion: Despite a low rate of radiographic healing, massive rotator cuff tears repaired
arthroscopically using our biceps incorporation technique showed high levels of patient
satisfaction and excellent/good functional outcomes on the basis of general, joint-specific, and
disease-specific outcome measures. The use of an arthroscopic technique of biceps
incorporation for the repair of massive rotator tears may result in improved clinical outcomes,
and a prospective, comparative evaluation of this technique with conventional methods of
repair is warranted.
207: Comparison of Biomechanical Characteristics of Three Arthroscopic Knots; the
Pretzel Knot, the SMC Knot and the Square Knot
Zeeshan M Sardar, QC; Hasan Sawan, QC; Russel Ward, QC; Thomas Steffen, QC; Moreno
Morelli, QC
Purpose: Arthroscopic knot tying is an integral part of arthroscopic shoulder surgery and
therefore surgeons performing arthroscopic shoulder surgeries should be proficient in such
knot-tying techniques. The ideal knot would have satisfactory loop security, knot security, easy
slidability, slack free configuration and a low profile on the tissues. We compare two commonly
used knots, the SMC (Samsung Medial Centre)knot and the Square knot , with a relatively
newer type of knot; the Pretzel Knot. The “Pretzel” knot is a type of a flip knot that is simple to
learn and prepare and pretzel shape is easily visualised to confirm correct knot technique.
Potential advantages of Pretzel knot include easy slidability because of only two half hitches
and low profile. It is also easy to teach and learn.
Method: The Pretzel knot was compared with two commonly used arthroscopic knots; the
SMC knot and the Square Knot. Four different suture materials were used to also detect the
effect of suture material on knot characteristics for the three knot configurations; (1) No. 2 HI FI
(CONMED, Polyethylene) , (2) No. 2 Force Fiber (Stryker, Ultra High molecular Weight
Polyethylene), (3) No.2 Ultrabraid (Smith&nephew) , (4) No. 2 FiberWire (Arthrex) , (5) No. 2
Johnson & Johnson. Five knots of each type were tied by the same senior surgeon with each
of the different suture materials accounting for a total of 25 knots for each knot type
Results: Our preliminary results show that the square knot is significantly stronger to the other
two knots because of the higher load to failure and higher resistance. There were no
statistically significant differences in the weight, failure to load and resistance between the
Pretzel knot and the SMC knot. There was significant difference in the weight of the Pretzel
knot when compared to the Square knot with the SMC knot being lighter.
Conclusion: The vast number of suture materials and types of knot configurations available
for Orthopaedics surgeons in the field of shoulder arthroscopy leaves the surgeon in a quest to
find the optimal combination when performing arthroscopic shoulder surgeries. The ideal knot
would have satisfactory loop security, knot security, easy slidability, slack free configuration
and a low profile on the tissues. Our study shows that the Pretzel knot exhibits these features
and is not inferior to the SMC knot. Considering it’s easy implementation, the Pretzel knot is
good option for experienced and less experienced Orthopaedic Surgeons.
208: Comparison of Pain and Medication use in Patients undergoing Double-bundle
versus Single-bundle Anterior Cruciate Ligament Reconstruction
Mark Heard, AB; Simon MacDonald, AB; Laurie A Hiemstra, AB; Gregory L Buchko, AB;
Sarah Kerslake, AB
Purpose: The purpose of this study was to compare the pain and medication use of singlebundle (SB) versus double-bundle (DB) anterior cruciate ligament reconstruction (ACLR)
patients in the acute post-operative period. In addition, spinal versus general anesthesia
approaches were analyzed for pain and medication use within both surgery types.
Method: A standard logbook was used to record self-reported pain and medication use by
patients who underwent SB or DB ACLR surgery. Pain was assessed using a 100mm visual
analog scale, and was recorded at specific intervals from the day of surgery until day 14 post-
operative. Medication use was recorded at these intervals over the same time period and
divided into three categories: 1) Oral opioids 2) Oral NSAIDS and 3) Acetaminophen.
Results: A total of 88 patients underwent SB and 41 patients underwent DB ACLR surgery.
Over the 14-day post-operative period, there was no statistically significant difference in mean
VAS pain scores between the SB and DB groups. However, pain differences between the two
procedures showed a general trend of the DB ACLR being more painful over the first 4 days
post-operative. There was also significantly more opioid and analgesia medications consumed
by the DB patient group over the 14-day period (p < 0.05). On average, for both DB and SB
procedures, patients who underwent spinal as opposed to general anesthesia experienced
less pain over the 14-day period, with a significant difference in pain at 1-hour post-operative
for both procedures (p < 0.001). For the DB ACLR procedure, opioid use was significantly
higher in patients who underwent general compared with spinal anesthesia over the 14-day
period (p < 0.001).
Conclusion: These results demonstrate patients in the DB group self-medicated to acceptable
levels of pain by consuming significantly more opioids than the SB patients; thereby indicating
the DB procedure was more painful. Patients who underwent spinal compared with general
anesthesia generally experienced less pain over the initial 14-day post-operative period.
209: Early Mobilization Following Mini-open Rotator Cuff Repair
Matthew Souster, AB; Rob Balyk, AB; Charlene Luciak-Corea, AB; Fiona Styles-Tripp, AB;
Martin Bouliane, AB; Jeff Bury, AB; Robert Glasgow Jr, AB; Lauren Beaupre, AB; David
Sheps, AB
Purpose: Mini-open rotator cuff repair (MORCR) is a common treatment for rotator cuff (RC)
disease. Traditional shoulder rehabilitation supports immobilization for the initial 6
postoperative weeks to promote tendon healing. However, delayed range of motion (ROM)
may slow the return of shoulder ROM, increase the risk of stiffness, and disrupt patients’
quality of life. The effect of early motion and the subsequent effect on clinical outcomes are
unknown in humans. We evaluated the clinical outcomes following MORCR treated with early
ROM compared to those who followed the standard immobilization protocol.
Method: 187 patients with radiographically-confirmed full-thickness RC tear underwent a
MORCR performed by fellowship-trained upper extremity surgeons (n=6). Subjects were
randomized to one of two treatment groups following a preoperative assessment of shoulder
pain, ROM, abduction strength and health related quality of life (HRQL) using a diseasespecific measure. During the first 6 postoperative weeks, subjects randomized to early
mobilization (n=97) self-weaned from the shoulder immobilizer and performed painfree active
ROM for activities of daily living (ADLs) while the standard immobilization group (n=90) wore a
sling. Both groups completed identical rehabilitation protocols after 6 weeks. Shoulder ROM
and pain were assessed at 6-weeks and three-months postoperatively. At 6-months, subjects
had their abduction strength and HRQL assessed in addition to shoulder pain and ROM.
Results: The two groups were similar preoperatively in power, ROM, HRQL, and pain
(p>0.10). Six-week ROM comparisons demonstrated that the early mobilization group had
increased abduction (p=0.03), flexion (p=0.01) and scaption (p=0.003), but these differences
disappeared by 3-months (p>0.32). There was no difference in power (p=0.85) or HRQL
(p=0.72) between groups at 6-months.
Conclusion: Patients who performed painfree active ROM for ADLs had no significant
difference in power, ROM, HRQL, or pain at 6 months compared to those who were
immobilized for 6 weeks following MORCR. Early ROM did not show any significant benefits
for minimizing long-term stiffness and pain, but clinically there was no compromise of their
postoperative shoulder power or HRQL. Consideration should be given to allow patients to
start actively using their shoulder within the first 6 weeks following a MORCR.
210: Initial Validity and Reliability of the Banff Patellar Instability Instrument (BPII)
Laurie A Hiemstra, AB; Mark R Lafave, AB; Sarah Kerslake, AB; S Mark A Heard, AB;
Gregory L Buchko, AB; Nicholas GH Mohtadi, AB
Purpose: Patellar instability is a common problem yet there are currently no published,
patient-reported, outcome measures that are disease-specific for this population. The purpose
of this study was to determine if the Banff Patellar Instability Instrument (BPII) is a valid and
reliable outcome for measuring quality of life in subjects with recurrent patellar instability.
Method: A modified Ebel procedure was employed to validate the content of the BPII. This
procedure is a three stage process consisting of: 1) simple validation by a local group of
experts; 2) formal adoption from an international group of experts; 3) face to face discussion of
international experts followed by modification of the instrument if 80% agreement did not occur
in the second stage. As a measure of internal consistency, Cronbach’s Alpha was utilized to
assess how reliably the 32 items of the BPII measured a similar construct (patellar instability).
One hundred and twenty patients with a confirmed diagnosis of patella instability from one of
the three orthopaedic surgeons completed the BPII at the initial orthopaedic consult (presurgery), 6 month follow-up appointment (post-surgery) and 12 month follow-up appointment
(post-surgery). Surgical procedures included medial patellofemoral ligament (MPFL)
reconstruction, MPFL imbrication, tibial tubercle transfer, knee arthroscopy or any combination
thereof. Data from each item of the BPII, as well as the cumulative score, was used in the
Cronbach’s Alpha Reliability Coefficient analysis.
Results: Content validity was clearly established as each item in the BPII achieved a minimum
of 83.3% (range 83.3-100%) agreement for relevance among the expert panellists at the
second stage of the modified Ebel procedure. The average agreement was 96.9% and 24/32
questions achieved 100% agreement. Reliability of the BPII was established at the initial
orthopaedic consult (reliability co-efficient = 0.91), 6 months post-operatively (reliability coefficient = 0.96) and 12 months post-operatively (reliability co-efficient =0.96).
Conclusion: This study has established the BPII is valid and reliable in patients with recurrent
patellar instability as well as patients who have had a patellar stabilization procedure.
211: Mechanical Stimulation Enhances Integration in an in vitro Model of Cartilage
Repair
John Theodoropoulos, ON; Am DeCross, ON; Sam Park, ON; Massimo Petrera, ON; Rita
Kandel, ON
Purpose: The ability of articular cartilage to self-repair is limited due to the nature of the tissue.
Tissue-engineered cartilage is a promising alternative for the treatment of cartilage injuries. It is
known that cartilage not stimulated by movement deteriorates with time. Although research has
focused on using mechanical stimulation to improve the mechanical properties of tissueengineered cartilage; there is little known about the effect of mechanical stimulation on the
integration of tissue-engineered cartilage with host cartilage. We have established an in vitro
model of repair cartilage integration using tissue-engineered cartilaginous tissue implanted into
host bovine articular cartilage. Based on the role of mechanical loading on tissue-engineered
cartilage properties, we hypothesized that mechanical stimulation would enhance the
integration of the repair implant with the adjacent host cartilage.
Method: Constructs composed of tissue-engineered cartilage implanted into host cartilage
were maintained in spinner bioreactors in the presence or absence of rotational forces (0 or 90
RPM). After 2 and 4 weeks of incubation, the constructs were evaluated for changes in gene
expression, matrix accumulation and extent of fusion at the integration site.
Results: Both time and mechanical stimulation in spinner bioreactors lead to improved
integration between host and implant tissue as determined histologically by semiquantifying
percent integration as well as biomechanically by a push-out test. Integration did not occur if
the implant was not viable. Collagen content significantly increased in the integration zone
between host and implant at 2 weeks. The gene profile of cells in the integration zone differs
from host cartilage demonstrating an increase in the expression of membrane type 1 matrix
metalloproteinase (MT1-MMP), aggrecan and type II collagen.
Conclusion: These results suggest that the integration of in vitro tissue-engineered implants
with host tissue improves with mechanical stimulation and that the implant is responsible for
integration.
212: PASTA Bridge - A New Technique in PASTA Repairs: A Biomechanical & Clinical
Evaluation
Alan Hirahara, US
Purpose: The purpose of this study was to evaluate the biomechanical and clinical
effectiveness of a new PASTA repair technique – PASTA Bridge.
Method: For the PASTA Bridge repair, a 17 gauge spinal needle, followed by a Nitinol wire,
dilation instrument, drill spear, a 1.8 mm drill, and then a 2.4 mm BioComposite SutureTak
(Arthrex, Naples, FL) was done twice to place the anterior and posterior anchors. Each anchor
position was approximately 5 mm from the centerline of the footprint. A strand of suture from
each anchor was tied in a similar manner as the “double pulley” method described by Lo. The
opposing two limbs were tensioned to pull the knot taunt over the repair site, and fixated
laterally with a 4.75 mm BioComposite SwiveLock (Arthrex, Naples, FL) placed approximately
1 cm lateral of the greater tuberosity. For the biomechanical evaluation, a 50% articular-sided
partial tear of the supraspinatus tendon was created on six matched pairs of fresh frozen
cadaver shoulders. From each matched pair, one humerus received a PASTA repair using one
4.5 mm titanium Corkscrew FT with a horizontal mattress suture while the contralateral repair
received a PASTA Bridge configuration.Each sample was pre-loaded to 10N followed by cyclic
loading between 10 and 100N, at 1 Hz, for 100 cycles. Post cycling, the samples were loaded
to failure at a rate of 33 mm/sec. Load and position data were recorded at 500 Hz, and the
mode of failure was noted for each sample. Displacement and strain was calculated using
video tracking and individual marks on the supraspinatus.For the clinical evaluation, thirty-one
patients had their PASTA lesions repaired with the PASTA Bridge while twenty-six patients
were repaired using a standard trans-tendon technique using a 3.7 mm BioSutureTak (Arthrex,
Naples, FL) with a horizontal mattress repair.Non-compliant patients and those suffering postop trauma were excluded. Patients were evaluated clinically with VAS pain scores, ASES
scores, days to discharge, and return to work. Repeat ultrasound or MRA was performed for
people having persistent pain to evaluate healing.
Results: For the biomechanical evaluation, there were no significant differences between the
two repairs in ultimate load (p = 0.577), strain at the repair site (p = 0.355), or strain at the
margin (p = 0.801). The modes of failure were the tendon tearing mid-substance, the humeral
head breaking, the muscle body tearing from the tendon, or the tendon tearing at the repair
site. All four of these modes of failure occurred in at least one sample from both repair groups.
Visual inspection of the samples post-testing revealed no damage to the anchors or suture
damage.For the clinical evaluation, four out of twenty-six (15.4%) control patients failed to heal,
requiring revision repair while only one out of thirty-one (3.2%) study patients failed to heal
(p<0.0001). Pain scores decreased and ASES scores increased in both groups from pre-op to
six months (Study: 7.4 to 3.1 & 39.9 to 68.2 / Control: 6.9 to 3.4 & 42.7 to 68.6, p=NS). Days to
discharge & return to work were 137.9 / 119.8 and 198.7 / 106.3 for Study / Control groups,
respectively (p= NS).
Conclusion: The biomechanical study showed that our PASTA Bridge construct creates a
very strong construct in repairing articular-sided partial-thickness tears of the supraspinatous.
There was no significant difference between this construct and a standard single suture anchor
for ultimate load or strain at the margins or repair site. The clinical results of this study show
that the PASTA Bridge technique was more effective than the standard trans-tendon technique
for healing but had similar decrease in pain and increase in function. This technique, in
contrast, is a percutaneous, simple procedure requiring no arthroscopic knot tying and carries
only a minimal chance of damage to the residual tissue. Further study to enhance the power of
this study is required.
213: Percutaneous Inside-out-outside-in Medial Meniscal Repair During Anterior
Cruciate Ligament Reconstruction: A Prospective Study
Nicholas GH Mohtadi, AB; Hamish Love, NZ
Purpose: This study describes a simplified hybrid suture repair technique for medial meniscal
tears and assesses the effect of medial meniscal injury and treatment on the outcome of
anterior cruciate ligament (ACL) reconstruction.
Method: A prospective comparative study (levels of evidence, level II). Two-hundred and
ninety-two patients treated with ACL reconstruction and concurrent treatment of meniscal
injuries. Patients were divided into treatment groups based on the management of the medial
meniscus into no treatment, repair or meniscectomy. Pre-operative, 6, 12 and 24-month clinical
assessment and outcome scores with ACL-Quality of Life and International Knee
Documentation Committee (IKDC) scores were performed.
Results: Meniscal tears were present in 66.7% of medial and 77% of lateral menisci in ACLdeficient knees. Over 50% of medial meniscal tears were amenable to repair. The groups were
comparable in terms of demographics, lateral meniscal pathology and ACL reconstruction
technique used. Meniscal repair added 9.6 minutes to the operative time. No operative
complications of meniscal repair were noted. At an average follow up of 21.3 months, no
significant difference in outcome scores was noted between treatment groups. The medial
meniscal revision rate was 7.1% with ongoing meniscal symptoms in a further 6.7%.
Conclusion: Medial meniscal repair using a simplified, hybrid suture technique is a safe and
efficient method for repairing medial meniscal tears. Success rates are equivalent to inside-out
suture techniques. Outcomes of ACL reconstruction, at least out to 2 years, are not
detrimentally affected by the presence of medial meniscal pathology, if treated appropriately.
214: Platelet-rich Plasma vs. Cortisone Injections for the Non-surgical Treatment of
Shoulder Pain
Alan Hirahara, US
Purpose: To evaluate pain and functional improvement in shoulder pain with PRP injections
versus cortisone
Method: This is a case-control, non-randomized study using 148 study patients who received
a PRP injection and 246 control patients who received a cortisone injection for shoulder pain.
Inclusion criteria were any patients having shoulder pain during the collection period already
having tried NSAID's and physical therapy. Patients were evaluated clinically with pain scores
and ASES scores for six months. Exclusion criteria were non-compliance with the physical
therapy regimen or post-injection trauma.
Results: Overall pain and ASES scores improved for both study and control groups (Study:
6.3 to 3.2 & 45.1 to 66.5 and Control: 6.8 to 3.7 & 40.1 to 63.3, p=NS) with statistically
significant improvement starting at days 2 and 1 (pain) and days 4 and 1 (ASES), respectively;
however, there was no statistical significance between the study and control groups at 6
months, but PRP showed significantly better pain/function during months 3-5. Patients with
tendonopathy and PASTA lesions all showed significant improvement in all measures but were
significantly better for the PRP study group by 5 months & 1 month, respectively (p=0.027 &
p=0.006). Patients with DJD did improve with a tendency for recurrence after a few months in
both groups but the cortisone group showed continued improvement significantly at 6 months
(p=0.026). Adhesive capsulitis and full thickness rotator cuff tears improved equally with either
cortisone or PRP injections, but RC tears only mildly.
Conclusion: This study shows that PRP injections are equivalent to cortisone injections to
help decrease pain and improve functionality in shoulder pain. However, each individual
diagnosis carries a different outcome with the different injections. Tendonopathy and PASTA
lesions had significantly better outcomes with PRP than cortisone injections. While pain in the
cortisone group usually returns, it usually did not with PRP. Cortisone does have a faster onset
than PRP, and cortisone did diminish pain longer in DJD patients over PRP. Patients with
adhesive capsulitis and full thickness RC tears had relief from PRP and cortisone equally.
Further study is required to evaluate each diagnosis individually to better elucidate the best
use of PRP
215: Validation of a Classification for Patients with Patellar Instability
Laurie A Hiemstra, AB; Mark R Lafave, AB; Sarah Kerslake, AB; S Mark A Heard, AB;
Gregory L Buchko, AB
Purpose: Patients with patellar instability present with a wide range of etiologies and
symptoms as well as varied anatomic and neuromuscular characteristics. As with shoulder
instability, these patient types present as a continuum. For patella instability, the authors
propose that two main subsets of patients present. This study introduces a novel classification
system, WARPS (Weak, Atraumatic, anatomy Risky, Pain, and Subluxation) and STAID
(Strong, Traumatic, Anatomy normal, Instability and Dislocation) The purpose of this study was
to demonstrate inter-observer reliability of the classification continuum of WARPS and STAID
for patella instability.
Method: Twenty-five consecutive patients with a confirmed diagnosis of patellar instability
were included. Each patient underwent a thorough history and physical examination
concurrently with 3 assessors (orthopaedic surgeon, physiotherapist and athletic therapist).
Each characteristic of the WARPS-STAID classification continuum was graded independently
by each examiner on a 10 cm VAS. Each assessor also assigned a cumulative WARPS-STAID
score to each patient. Intraclass Correlation Coefficient (ICC 3,3) was calculated for each pair
of characteristics on the continuum and for the cumulative scores.
Results: Intraclass Correlation Coefficient (3,3) of the WARPS-STAID classification continuum
were W-S = 0.92; A-T = 0.95; R-A = 0.81; P-I = 0.84; and S-D = 0.91. The ICC (3,3) of the
composite score was 0.84.
Conclusion: These results demonstrate strong reliability of the classification system, WARPSSTAID for patients with patella instability. The classification system reliably differentiates
between two distinct subsets of patella instability patients.
216: Cefazolin use in Patients with a History of Non-IgE Mediated Penicillin Allergy
Nazari Dvirnik, ON; Sean Haslam, ON; David Yen, ON; Dale Engen, ON
Purpose: To demonstrate the safe use of Cefazolin in patients with non-IgE mediated allergy
to penicillin. To document the reported adverse reactions to penicillin and the number of cases
the reactions are unknown despite a stated allergy to penicillin. To determine if a unified
practice of using Cefazolin in all patients with non-IgE mediated penicillin allergy could be
followed in a Health Centre.
Method: The participants of this prospective quality control study were all the patients with a
reported penicillin allergy who were of ages 18 and over, who were scheduled for surgeries
that required prophylactic antibiotics at the Hotel Dieu and Kingston General Hospital between
May 20, 2011 and August 9, 2011. Previous reactions were recorded from patient interviews
and patients with non-IgE mediated penicillin allergies were given Cefazolin in a safe clinical
setting and any allergic reactions were to be treated and documented.
Results: Out of a total of 3551 patients, 430 stated an allergy to penicillin (12.1% allergy
prevalence). Out of these, 2276 cases had the study inclusion criteria (age >18y, preferred
cefazolin prophylaxis), in which 192 patients stated an allergy to penicillin. In our penicillin
allergic study population, 70 patients (36.1%) reported IgE-mediated reactions, 101 patients
(52.6%) reported non-IgE-mediated reactions and 21 patients (10.9%) had unknown reactions.
Seventy-five patients (61.5%) with non-IgE-mediated allergies or unknown reactions received
prophylactic Cefazolin. None of the study patients had immediate reactions to Cefazolin.
Conclusion: A significant number of patients having elective surgery requiring prophylactic
antibiotics state that they have an allergy to penicillin. A large proportion of the reactions in this
patient group are non-IgE-mediated or unknown. Cefazolin can be safely used in these
patients thereby reducing the use of alternative antibiotics like Vancomycin and Clindamycin
with their associated risks. Despite an antibiotic use protocol pre-circulated by the physician
manager, a unified practice of using Cefazolin was not followed.
217: Does A Dedicated Perioperative Cardiovascular Service Improve Patient-Important
Outcomes?
Justin de Beer, ON; Tammy Cosman, ON; Bill Evans, ON; Kim Alvarado, ON; Vikas Tandon,
ON; Patrick Magloire, ON; Omid Salehian, ON; Tej Sheth, ON; Hisham Dokainish, ON;
Sebastian Ribas, ON; George Stallwood, ON; Chuck Tomlinson, ON; Deborah Hastings, ON;
Greg Curnew, ON; Mitch Winemaker, ON; Diane Heels - Ansdell, ON; PJ Devereaux, ON
Purpose: Over 5 million adults suffer a major vascular complication within 30 days after
noncardiac surgery annually. In an attempt to improve these outcomes at the Juravinski
Hospital and Cancer Centre (JHCC), we initiated a Perioperative Cardiovascular Service
(PCS) run by a nurse practitioner and the cardiology attending physician. The PCS was
initiated on January 1, 2010. The PCS systematically screened all orthopedic surgery patients
prior to surgery, performed a preoperative consult on all at-risk patients, determined the post
operative care setting and monitoring requirements, and co-managed orthopedic surgery
patients at-risk of a perioperative major vascular complication. The objective of this study was
to determine whether the PCS improved the incidence of major vascular complications after
orthopedic surgery.
Method: We undertook a before-after study to evaluate the impact of the PCS. Patients aged
>45 years who required at least an overnight hospital admission after undergoing orthopedic
surgery were eligible. Patients who had surgery during the day or night, weekday or weekend,
and who underwent an elective or urgent/emergent surgery were included. From October 22,
2007 to August 28, 2008 we recruited a representative sample of eligible orthopedic surgery
patients at the JHCC to the Pre-PCS group. From March 1, 2010 until August 8, 2011 we
recruited a representative sample of eligible orthopedic surgery patients at the JHCC to the
Post-PCS group. All patients had a Troponin T measurement 6-12 hours after surgery and on
days 1, 2, and 3 after surgery. Independent research personnel collected all outcome data. We
assessed major vascular outcomes in the Pre-PCS and Post-PCS groups, and we undertook
multivariable logistic regression analyses to determine if the PCS independently impacted
major perioperative vascular complications.
Results: We recruited 863 patients into the Pre-PCS group and 527 patients into the PostPCS group. In the Pre-PCS group the mean age was 69.1 years (SD 11.0), 58.7% of the
patients were female, and 53.4% of the patients underwent knee arthroplasty. In the Post-PCS
group the mean age was 67.8 years (SD 11.8), 57.1% of the patients were female, and 49.7%
of the patients underwent knee arthroplasty. Fewer patients in the Post-PCS suffered a
myocardial infarction (MI) (2.5% versus 5.0%, P=0.049) and congestive heart failure (CHF)
(0.9% versus 3.2%; P=0.006). Our multivariable risk adjusted analysis demonstrated patients
in the Post-PCS group had a lower risk of the composite outcome of MI or CHF (OR, 0.51,
95% CI, 0.27-0.96, P=0.036).
Conclusion: These data suggest that a PCS may prevent MI and CHF after orthopedic
surgery.
218: Does a Surgery on Known Infected Arthroplasty Cases Impact the Infection Rate of
Clean Arthroplasty Cases in the Same Operating Room?
Mansour Abolghasemian, ON; Amir Sternheim, ON; Alireza Shakib, ON; Oleg Safir, ON;
Allan E Gross, ON; David Backstein, ON
Purpose: Infection is a serious and highly morbid potential complication of joint arthroplasty.
Every attempt is employed by the surgical team to decrease the load of bacteria in the
operating room and in some places it is standard practice to close a room after a surgery on a
known infected case until a thorough cleaning of the area is performed, usually over night.
There is no evidence however, on necessity of this protocol. The present study was designed
to investigate if there is any increased risk of infection when a non-infected joint replacement
procedure is performed after an infected operation, in the same room, using standard O.R.
cleaning protocols.
Method: A retrospective review of all primary or revision total joint arthroplasties performed
over a 4-year period (2007-2010) at our institution was conducted. Patients who underwent hip
or knee arthroplasty immediately following a case of known infection in the same operating
room were analysed (for the first six months after surgery, when infections may be attributed to
contamination at the time of surgery) to determine the incidence of infection. This group of
patients were matched regarding gender, age and surgery type to a large control group of
patients operated on in the same period of time but were not performed in an OR which had
just been used for an infected case. Culture data was collected for all infection occurrences.
The rates of superficial and deep infections in the case and control groups were compared
statistically.
Results: A total of 58 hip or knee arthroplasty cases, including 10 revisions and 48 primaries,
were eligible for the study group. They were all operated as the second case of the day
immediately following a case of first stage revision for treatment of an infected joint. There was
only one case of deep infection in the study group (1.7%) which occured in a primary total
knee arthroplasty caused by Strep. viridians. The organism of the preceding infected case was
Staph. aureus. One case of superficial infection (1.7%) was also identified. Two cases (3.4%)
showed prolonged wound discharge after surgery. The control group included 354 joint
replacements. There was one deep (0.28%) and 12 superficial (cellulitis or stitch abscess)
infections (3.4%) and four prolonged wound drainage (1.1%) among them. Statistical analysis
did not show any significant differences between the groups regarding deep (P value, 0.121) or
superficial (P value, 0.21) infections or prolonged discharge rate (P values, 0.17).
Conclusion: While the predisposing factors for deep and superficial infections are multiple, the
role of a preceding infected case as a risk factor for infection of the following case does not
appear to be well founded. There was only one deep infection in each group. This does not
represent a statistically higher rate than the control group. Importantly, the single infection in
the study group was not caused by the same organism as the preceding infected case, thus
raising doubt about any relationship between the two. Superficial infections were not more
prevalent in the case group. Of note, the sterility protocol in our operating room is a routine one
which does not use laminar flow, body exhaustion systems or ultraviolet radiation. In summary,
this study failed to show any increased risk of infection in primary or revision arthroplasties
performed following an infected case. The authors see no indication for OR cleaning protocols
beyond standard accepted methods, for joint replacements after infected cases.
219: Effectiveness Of A Medically Supervised Weight Loss Program For Morbidly Obese
Women With Severe Knee Osteoarthritis: Two Year Follow-Up
Stephen M Mann, ON; Mark M Harrison, ON; Alice B Aiken, ON; Brenda Brouwer, ON;
Kamary Coriolano-Da Silva, ON
Purpose: To determine the extent to which benefits, including improved pain, psychological
status and functional abilities, attained from a medically monitored rapid weight loss program
for morbidly obese women with knee osteoarthritis, persisted at two-year follow up.
Method: Thirty-four women (age 45 to 66) with morbid obesity and severe osteoarthritis of the
knee that presented to an orthopedic surgeon for total knee arthroplasty were offered
enrollment into a medically supervised weight loss program prior to consideration of a total
knee replacement. Twenty-six subjects chose to participate in the weight loss program. They
were enrolled in the Dr. Bernstein diet program, (a low-calorie, low-fat diet) at no cost to them.
We initially collected the following questionnaires at enrollment and every six weeks while they
remained in the weight loss program: WOMAC, SF36, Self-Efficacy, Health Locus of control,
Dieting Beliefs Scale, Body Image State Scale, and the Beck Depression Inventory as well as
Functional tests, namely the Timed Up and Go (TUG) and 6 Minute Walk Test
(6MWT).Previously presented data indicated that weight loss led to significant improvements in
pain and functional ability, and alleviated or delayed the need for total knee arthroplasty in the
majority of morbidly obese middle-aged women.At a minimum of two years following initial
enrollment, participants were contacted and asked to undergo repeat administration of
questionnaires and functional tests.Our hypothesis was that the benefits initially obtained from
weight loss would not be maintained over two years.
Results: Fifteen of the initial 34 subjects were available for follow up. There were no
statistically significant differences in BMI, TUG or 6MWT, nor in scores on the WOMAC, SF36,
Self-Efficacy, Health Locus of control, Dieting Beliefs Scale, Body Image State Scale, or the
Beck Depression Inventory between initial evaluation and two-year follow up. The mean
change in BMI between initial and follow-up was -2.2, and all but two patients weighed more
than their lowest recorded weight during the study period. No patient was satisfied with her
current weight at follow up.Three patients who presented for follow up had undergone an
operative intervention for knee osteoarthritis, and another six patients were identified as having
had surgery by radiographic review.
Conclusion: While a low-fat, low-calorie medically monitored weight loss program is initially
effective in achieving significant weight loss in morbidly obese women with severe knee
osteoarthritis with resultant improvements in pain and functional ability, these benefits are not
sustained at two-year follow up. Further analysis of cognitive and psychological factors may
prove valuable in identifying a subgroup which will improve with conservative management
220: Family History of Total Joint Arthroplasty and Joint Space Width Narrowing on
Plane Radiographs: Data from the Osteoarthritis Initiative (A Prospective Multicenter
Study)
Kenneth D Illingworth, US; Donald N Sullivan, US; Jacob D Sams, US; Steven L Scaife, US;
John Horberg, US; Khaled J Saleh, US
Purpose: Previous studies have shown a positive correlation between genetic factors and the
predisposition for end stage osteoarthritis suggesting family history plays a role. Currently,
plane radiography imaging provides the most consistent, quantifiable measure of joint disease
and subsequent progression. The purpose of this study was to quantify joint space width
narrowing on plane radiographs in patients with a positive family history of total joint
arthroplasty and compare with patients with no family history.
Method: Data used in the preparation of this article were obtained from the Osteoarthritis
Initiative (OAI) public use data set (kXR_QJSW_Duryea16). Of the 1,805 patients (3,257
knees) patients with joint space width quantified, 218 knees in 137 patients had a positive
family history of total joint arthroplasty and 503 knees in 335patients had no family history of
total joint arthroplasty. Any patient with a previous history of knee surgery was excluded.
Patients were separated into 3 age groups; 45-54, 55-64 and 65-74. All patients had standing
flexion weight bearing posterior to anterior plane radiographs at baseline, 12, 24, 36 and 48
months. Mean medial and lateral joint space width was calculated using specific data points for
each compartment; 7 measurements for the medial compartment and 9 measurements for the
lateral compartment. Mean joint space width in the medial and lateral compartment was
analyzed at each time point. Patient demographics obtained included BMI, abdominal
circumference, gender, race, income and smoking in packs per year. Pearson correlation
coefficients were used to compare joint space narrowing to age in both groups. Independent Ttests with a significance of p < 0.05 were used for comparison between all groups.
Results: No significant difference was found between the two groups in regards to patient
demographics. There was a statistically significant correlation between age in the non family
history group (r = 0.26, p < 0.05) and the family history group (r = 0.30, p < 0.05). There was a
statistically significant difference between medial and lateral joint space width in patients with a
positive family history of total joint arthroplasty when compared to no family history at all time
points in patients 65-74 years of age (p < 0.05). The average difference in joint space width
between positive family history and no family history in this age group was 0.61 mm. Rate of
joint space loss per year was also significantly higher in the family history group than the no
family history group in both the medial (0.17 mm, 0.12 mm) and lateral (0.14 mm, 0.11 mm)
tibiofemoral compartments (p < 0.05).
Conclusion: An increasing age is associated with decreasing tibiofemoral joint space width.
Patients between the ages of 65 – 74 with a positive family history of total joint arthroplasty
have a significant decrease in joint space width on plane radiographs as well as an increased
rate of joint space loss.
221: Patients’ Views On Surgeons’ Financial Conflicts Of Interest
Mark W Camp, ON; David A Mattingly, MA; Allan E Gross, ON; Markku T Nousiainen, ON;
Benjamin A Alman, ON; Martin F McKneally, ON
Purpose: Revelations of kickbacks from surgical device manufacturers to orthopaedic
surgeons raise the question whether surgeons can continue to collaborate with industry and
maintain public trust. We explored post-operative arthroplasty patients’ views on financial
relationships between orthopaedic surgeons and surgical device manufacturers, their views on
disclosure as a method to manage these relationships and their opinions on oversight. We
present our findings here to add needed surgical patient perspectives to the discussion of how
physicians and surgeons can work productively with industry and still maintain public trust.
Method: We surveyed 251 post-operative U.S. patients (an 88% response rate) and 252 postoperative Canadian patients (a 92% response rate) in follow-up hip and knee arthroplasty
clinics. We developed our survey questionnaire by conducting preliminary qualitative
interviews with post-operative arthroplasty patients at an academic hospital in Toronto. Their
views on conflicts of interest were analyzed and these patient-derived concepts were used to
draft our survey questions. We added relevant themes and questions found useful in previous
surveys. We tested a questionnaire derived from these sources on non-surgical volunteers and
post-operative arthroplasty patients, using cognitive interviews to ensure that questions would
be understood. The final questionnaire contained items in six domains: trust, awareness and
concern about financial relationships between surgeons and device manufacturers, opinions
regarding oversight, attitudes towards disclosure of financial relationships, socio-demographic
data, and surgical characteristics.
Results: Few patients are worried about possible financial relationships between their surgeon
and industry (6% of U.S. patients and 6% of Canadian patients surveyed). Most patients
thought that it is appropriate for surgeons to receive payments from manufacturers for activities
that can benefit patients, such as royalties for inventions (69% and 66%) and consultancy
(48% and 53%). Most patients felt that it is not appropriate for their surgeon to receive gifts
from industry (63% and 59%). A majority felt that their surgeon would hold patients’ interests
paramount regardless of any financial relationship with a manufacturer (76% and 74%). A
majority of patients wanted their surgeon’s professional organization to ensure that financial
relationships are appropriate (83% and 83%); a minority endorsed government oversight of
these relationships (26% and 35%).
Conclusion: Few patients were worried about possible financial relationships between their
surgeon and industry. Patients clearly distinguish financial relationships that benefit current or
future patients from those that benefit the surgeon or device manufacturer. They view
disclosure, without professional oversight as an insufficient method of managing financial
relationships between surgeons and manufacturers.
222: Prospective Observational Study of Thromboembolic and Bleeding Events
following Elective Hip and Knee Arthroplasty using Oral Factor Xa Inhibitor
(rivaroxaban) for Thromboprophylaxis
John J Murnaghan, ON; Jeffrey Gollish, ON; Deborah Anne Murnaghan, ON; Helen Razmjou,
ON; Vikas Bansal, ON; Andrea Donovan, ON
Purpose: The aim of this study was to prospectively document the incidence of
thromboembolic and bleeding events in patients who received rivaroxaban as the primary
prophylaxis.
Method: Prospective, observational study of patients given oral Factor Xa inhibitor
(rivaroxaban) following primary and revision Total Hip Arthroplasty (THA) and Total Knee
Arthroplasty (TKA). All patients were approached to participate and consented. Patients
treated with Rivaroxaban 10 mg po daily starting Post-Operative Day (POD) #1 for 15 days.
Participants followed-up at 6 weeks and 3 months. Doppler ultrasound or venograms used to
diagnose proximal DVT. Spiral CT, CT Angio or V/Q scan were used to diagnose PE. Bleeding
complications were documented as ‘on prophylaxis’ starting 2 hours after first dose of
anticoagulant therapy until 24 hours after the 15th dose. Research ethics approval was
obtained.
Results: From June 2010 to April 2011, 1686 patients underwent total joint arthroplasty: 1554
(92%) agreed to participate in the study. Of these,1527 patients were followed up at 3 months
(98%). Twenty-seven patients were lost to follow-up. Complete data on 1527 patients is
reported: 621 men, 906 women with mean age 66 years. TKA 929 (primary 823, revision 63,
bilat 43). THA 637 (primary 574, revision 63). Patients received rivaroxaban: 1434. DVT: Five
DVT reported by 3 months: 2 primary TKA and 3 Primary THAs. Total DVT= 5/1434= 0.3%.
PE: There were 12 confirmed PE by 3 months: 7 TKA, 4 THA and 1 Revision THA. Total PE
12/1464=0.8%. Bleeding: Two major and 6 non-major surgical-site bleeds occurred. One major
and 3 non-major non-surgical site bleeds occurred in patients who received rivaroxaban.
Transfusion: Seventy-three (5%) received blood transfusions with no difference between
patients who received rivaroxaban and those who did not (Fisher’s exact test: 0.17,
p=0.17).There were two perioperative deaths which were not related to surgery, DVT,
pulmonary embolism or bleeding.
Conclusion: The incidence of thromboembolic events within a period of 3 months was 5/1434
(0.3%) for DVT and12/1434(0.8%) for PE. The incidence of major bleeding was 3/1434 (0.2%).
There were no deaths related to DVT, PE or bleeding.These preliminary findings are similar to
thromboembolic and bleeding event rates in the research trials ( symptomatic VTE 0.2-0.7%
and major bleeding.0.1-0.7%).Our DVT and PE event rates may be higher than those reported
in the RECORD trials because we treated all patients after all procedures for 15 days and
followed them for 90 days. A number of events occurred after 6 wks follow-up: 4 DVT’s and 4
PE’s. Five out of 7 in-hospital PE’s occurred in TKA. Preliminary results are surprising for the
number of pulmonary emboli which occurred while patients were still in hospital and for the
number of DVT's which occurred between 6 weeks and 3 months. Further work is required to
see if these trends are maintained. This study is ongoing.
223: Total Joint Replacement Readmission Rates and Reasons for Readmission
Victoria R Avram, ON; Justin de Beer, ON; Will Ngai, ON; Danielle Petruccelli, ON; Mitch
Winemaker, ON
Purpose: A retrospective review of primary total joint replacement (TJR) patients was
conducted to determine readmission rate and reasons for readmission within the first 28 days
of discharge. Based on current institutional pressures to reduce acute hospital length of stay, it
was hypothesized that “failure to cope” would be a significant factor for hospital readmission
within 28 days of discharge.
Method: Primary total knee (TKA) and total hip arthroplasty (THA) patients readmitted to
hospital within 28 days of discharge were abstracted from a prospectively tabulated
arthroplasty database of 4445 patients who underwent primary TKA or THA at one academic
hospital between 2004 and 2008. Patient demographics, preoperative comorbidity profile, and
reason for readmission were abstracted. Data were analyzed using descriptive statistics.
Comparison of demographics and comorbidity profile between readmit patients and nonreadmitted patients over the same study period were analysed using independent samples ttest and chi-square test.
Results: A total of 95 readmitted patients were identified, including 40 primary THA and 55
primary TKA patients, giving a readmit rate of 2.1% within 28 days of discharge. Mean number
of days between discharge date and readmission date was 9.24 (±7.2). A total of 5/95 (5.3%)
were readmitted for “failure to cope”. The most common reasons for readmission were found to
be septic complication (22/95, 23.2%), cardiovascular event (16/95, 16.8%), and “cellulitis”
(14/95, 14.7%). Of those readmitted for septic complication related to the joint, 9/22 (40.9%)
required revision THA/TKA within 1 year of index surgery. No significant correlation was found
between being diabetic and experiencing a septic complication (p=0.510); cardiovascular
history and readmission for cardiovascular event (p=0.063), or preoperative ASA ratings and
readmit for cardiovascular event (p>0.05); or thrombo-prophylaxis related history and
readmission for a thrombo-prophylaxis related complication (p=0.519). The demographic
profile of readmitted patients closely mirrors that of all patients who underwent primary TJR at
our centre over the same timeframe. Although readmit patients are significantly older (68.3 vs.
71.4 years, p=0.006), this 3 year difference is neither clinically relevant nor clinically significant.
Conclusion: The readmission rate among individuals who had a primary TJR was 2.1%. Only
5.3% were readmitted for “failure to cope”. Contrary to our hypothesis, the principle reason for
readmission was septic complication related to the operative joint including both superficial and
deep surgical site infections which comprised 23% of the sample, and cardiovascular event
which comprised 17% of the sample. These diagnoses are reported to be more common
postoperative complications associated with total joint replacement.
224: Web-Based Joint Replacement Follow Up Assessments: Are Routine Clinic Visits
Necessary in 2011?
Steven JM MacDonald, ON; Jacquelyn Marsh, ON; Douglas Naudie, ON; Richard McCalden,
ON; James P McAuley, ON; James L Howard, ON; Dianne Bryant, ON
Purpose: It has been recommended that patients undergoing total hip, or total knee,
arthroplasty be seen for routine followup at regular intervals to monitor the performance of the
implant and bearing. However, the vast majority of these followup clinic visits are routine, with
no change in clinical outcomes. Technology and resources now exist to enable patient
assessment without physically coming to see the surgeon. The purpose of this study was to
measure the feasibility and costs associated with a Web-based assessment compared to the
usual method of follow-up.
Method: We randomized patients who were at least 12 months post-operative to either
complete a Web-based follow-up (which included completion of an online form and an xray
done at nearest web-enabled facility) or to have their appointment at the clinic as usual. We
recorded travel distances, costs, time in xray, time in clinic and time taken off paid
employment.
Results: A total of 210 patients (96 THA, 114 TKA) completed the study with a mean age of
68.5 years. Patients in the Web-based group travelled less (29.1 vs 110.2 kms, (p<0.01)), had
lower associated travel costs ($4 vs $ 21.41, (p<0.01)) and reduced associated time (44.6
mins for online form completion vs 55.6 min clinic visit). Patients missed 5.7 hours from work
and caregivers 6.4 hours to attend the clinic appointment.
Conclusion: There were significant time and costs savings to patients in the Web-based
group. Other potential advantages of Web-based follow-ups include decreased wait times in
clinic for existing patients with problems or new patients waiting for surgery, and reduced
patient and caregiver burden by decreasing travel distances, financial and time requirements.
225: Assessment of Radiographic Fracture Healing in Patients with Operatively Treated
Femoral Neck Fractures
Mohit Bhandari, ON; Brad Petrisor, ON; Olufemi Ayeni, ON; Simrit Bains, ON; Rajesh
Chakravertty, ON; Meg Chiavaras, ON; Hema Choudur, ON; Naveen Parasu, ON; Sheila
Sprague, ON
Purpose: The reliability of assessing fracture healing in femoral neck fractures has not been
adequately addressed in both research and surgical practice. The purpose of the present study
was to determine the reliability of fracture healing assessment and the validity of a novel
Radiographic Union Scale for Hip (RUSH) fracture score.
Method: A panel of 6 reviewers (3 orthopaedic surgeons and 3 radiologists) independently
assessed fracture healing for 150 femoral neck fractures at two separate occasions with a time
lapse of 4 weeks to determine inter-rater and intra-rater reliability. Assessment was performed
using radiographs for each case at a single time point at various stages of healing. The RUSH
score was developed based on the existing criteria and definitions of hip fracture healing, and
as such incorporated the assessment of callus bridging and disappearance, trabecular
consolidation, and trabecular disappearance. Reviewers used this to score each fracture on a
scale from 10 to 30. This would help to determine the validity of using this system to quantify
hip fracture healing.
Results: Using subjective assessment of fracture healing, the inter-rater agreement between
all reviewers for fracture healing was low (intraclass correlation coefficient (ICC) = 0.32, 95%
confidence interval (CI): 0.20-0.46) with no significant difference between the orthopaedic
surgeon and radiologist groups (0.27 vs. 0.31). There was higher agreement for fracture
healing using the RUSH score (ICC=0.63, 95% CI: 0.34-0.79) when compared to physician
assessment of healing (ICC=0.37, 95% CI: 0.10-0.59). Intra-rater agreement was consistently
high across all measures for both surgeons and radiologists. The RUSH score and medial
cortex bridging correlated well with the overall assessment of healing (Pearson’s correlation (r)
= 0.868 and 0.643 respectively). 6 of 7 (85.7%) fractures less than two weeks after surgery
were deemed healed by reviewers.
Conclusion: In the absence of time of xray evaluation, the level of agreement between and
within orthopaedic surgeon and radiologist reviewers in the assessment of fracture healing is
low, though intra-rater agreement is high. Assessments were improved with the use of a simple
radiological checklist (RUSH). Studies evaluating reliability and accuracy of healing with clinical
information and temporal evaluation are needed and may improve agreement.
226: Does Weight-bearing Status following Surgery for Hip Fracture Impact Outcomes?
Cai Wadden, ON; Steven R Papp, ON; Wade T Gofton, ON; Allan Liew, ON; Alan Forster, ON;
Kevn Rasuli, ON
Purpose: The purpose of this study was to determine if there was a difference in acute care
length of stay (LOS) and complication rates following surgery for hip fracture between patients
who were weight-bearing as tolerated (WBAT) and those with an altered weight-bearing (AWB)
status.
Method: All patients undergoing surgery for hip fracture between January 1st of 2005 and
June 30th of 2006 at a single centre were evaluated. Only those patients with an intertrochanteric hip fracture, OTA classification 31-A, were included in the study. Patients who
sustained their fracture while admitted to hospital or suffered poly-trauma were excluded.
Results: During this 18 month period we identified 130 patients who underwent hip fracture
surgery and had an OTA 31-A type fracture. Of these 32% were 31-A1, 62% were 31-A2 and
6% were 31-A3. Overall, 76% of patents were WBAT following surgery with the remaining 24%
being either toe-touch weight-bearing (TTWB), partial weight-bearing (PWB) or non weightbearing (NWB). Weight-bearing status did not correlate with either post-operative complication
rates or acute care length of stay. Minor complications were greater in the WBAT group
compared to the AWB group, 51% versus 32%. Major complication rates were similar between
the two groups, 16% in the WBAT group versus 19% in the AWB group. Acute care length of
stay was also similar between the WBAT and AWB groups, 13.0 days versus 12.8 days
respectively. Failure rates at 12 months were also similar between the groups.
Conclusion: Based on this data weight-bearing status does not appear to have a negative
impact on acute care length of stay and either minor or major complication rates. Given that
almost one quarter of patients have an altered weight-bearing status (NWB, TTWB or PWB)
post-operatively without an associated impact on LOS or complications, we are likely over
restricting patients weight-bearing status post-operatively and negatively affecting their ability
to mobilize.
227: Effect of Starting Position on Distal Cephalomedullary Nail Position for Fixation of
Peri-trochanteric Fractures in Osteoporotic Bone
George Xenoyannis, ON; Kelly Trask, NS; Ross K Leighton, NS
Purpose: Distal anterior cortical perforation is a potential complication with the use of long
cephallomedullary nails for peri-trochanteric fractures which occur proximal to the isthmus of
the femur. The purpose of this study was to evaluate the effect of sagittal plane start-point for a
trochanteric entry femoral nail on distal nail position.
Method: This was a biomechanical study conducted on sawbone femurs utilizing an
osteoporotic femur bone model. Three different sagittal plane starting points were used with
one centrally at the tip of the greater trochanter (M) and the others one centimetre anterior (A),
and one centimetre posterior (P) to start point M. Five trials were performed at each entry point
using a reamed trochanteric entry antegrade femoral nail inserted according to manufacturer’s
instructions. A radiolucent ruler from the nail set was secured to the anterior cortex of femur
and fluoroscopy was used to identify at what insertion depth the nail impinged on the anterior
cortex of the femur. Impingement was defined as the point the nail could no longer be inserted
easily by hand. The final distance from the tip of the nail to the anterior cortex was also
measured once the nail was completed seated. The known diameter of the nail was used to
adequately scale the radiographs for the measurements taken.
Results: With an anterior entry point (A) the average position of the tip of the nail relative to
the anterior cortex was 17.2 mm. With a central entry point (M) this distance was 9.6 mm while
with a posterior entry point (P) the distance decreased to 3.4 mm. A one-way ANOVA
demonstrated a significant difference between the distal position of the nail and proximal entry
point (p <0.001). A post-hoc analysis done between paired groups showed that use of a
posterior entry point resulted in a significantly more anterior position for the distal end of nail
than an anterior (p<0.001) or middle (p<0.001) entry point. There was no impingement on the
anterior cortex when start points A or M were used. However, with start point P the nail
impinged on the anterior cortex at an average distance of 20.5 cm from the tip of the greater
trochanter.
Conclusion: This is the first study to determine the effect of an anterior or posterior starting
position with a modern nailing system. The saggital plane position of the start point for a
femoral nail can affect the distal positioning of the nail. A more posterior start point leads to
anterior cortical impingement earlier during nail insertion. In addition, the distance from the tip
of nail to the anterior cortex is decreased with a more posterior start point. In osteoporotic bone
we recommend a central to just slightly anterior sagittal plane start point for a trochanteric entry
femoral nail.
228: Entry Point for Intramedullary Nailing of Femoral Shaft Fractures: A Systematic
Review and Meta-analysis
Farrah Hussain, ON; Nasir Hussain, ON; Amir Sternheim, ON; Emil H Schemitsch, ON; Paul
RT Kuzyk, ON
Purpose: Intramedullary (IM) nailing of femoral shaft fractures is an effective treatment
method. However, there is debate in the literature concerning the best entry point. The
purpose of this meta-analysis was to identify significant differences in outcomes of studies
comparing: 1) trochanteric and piriformis entry, and 2) antegrade and retrograde entry in IM
nailing of the femur.
Method: We searched MEDLINE, COCHRANE and EMBASE, and the Orthopaedic Trauma
Association and American Academy of Orthopaedic Surgeons websites for comparative
studies published from inception to May 2011. References from relevant articles were also
searched. Criteria used to select articles for detailed review included use of antegrade and
retrograde entry point or use of trochanteric and piriformis entry point for IM nailing of the
femur in adult patients. The following outcomes were extracted from eligible studies: rates of
reoperation, dynamization, union, malalignment, nonunion, delayed union, pain, complications,
mortality, operative duration, blood loss, and functional outcome in patients with femoral shaft
fractures.
Results: We found 10 publications and 2 abstracts (2 Level-I, 6 Level-II and 4 Level-III
studies) that met the eligibility criteria: 8 comparing antegrade with retrograde entry, and 4
comparing trochanteric with piriformis entry. Pooled data did not indicate significant differences
in malalignment, rates of reoperation, union, or non-union/delayed union in either comparison.
There were significant differences in pooled data favouring retrograde nailing for operative
duration, hip pain and heterotopic ossification, and favouring antegrade nailing for knee pain.
There was Level-II and -III evidence showing significant differences in knee function and range
of motion favouring antegrade nailing and Trendelenburg gait and blood loss favouring
retrograde nailing. No significant differences were found in pooled data for studies comparing
trochanteric with piriformis entry. There was Level-I evidence showing significant differences in
hip range of motion favouring trochanteric nailing.
Conclusion: Although some significant differences were found, the varying quality of studies
made recommendation difficult. On the basis of available evidence, it appears that retrograde
nailing is favourable in terms of shorter operative duration with risks of knee pain, while
antegrade nailing carries risks of hip pain and heterotopic ossification. No reliable conclusions
can be made with regards to the entry point for antegrade nailing. Higher level studies using
consistent endpoints for comparison are recommended.
229: Open Reduction Internal Fixation vs Acute Total Hip Arthroplasty for the Treatment
of Displaced Acetabular Fractures in Older Patients
Jonah Hébert-Davies, QC; G Yves Laflamme, QC; Olivier Chemaly, QC; Dominique M
Rouleau, QC
Purpose: Acetabular fractures in older patients are often the result of low energy trauma with
many studies identifying age as an independent factor leading to poor outcome. Standard
treatment of displaced acetabular fractures remains open reduction and internal fixation (ORIF)
however, there is an emerging subset of patients where ORIF combined with an acute total hip
arthroplasty (THA) may be a more reasonable alternative. The purpose of this study was to
evaluate and compare the functional outcome of ORIF and THA in the older patients with an
acetabular fracture.
Method: We conducted a retrospective comparative cohort study at our Level I Tertiary care
university hospital. All patients above 50 years old with an acetabular fracture were included.
Patients received either open reduction and internal fixation (ORIF) or Acute total hip
arthroplasty (THA). Indications for Arthroplasty were: femoral head impaction or fracture, preexisting osteoarthritis, associated femoral neck fracture, posterior wall comminution, roof
impaction and severe osteopenia. Functional outcome scores were collected using the SF-12,
WOMAC and Harris Hip score.
Results: There were 28 patients in the ORIF group and 20 patients in the arthroplasty (THA)
group with an average follow-up of 40 months. The two cohorts were comparable except for
surgical approach. The mean Harris hip score were not statistically different with 77.9 THA vs
78.9 ORIF. Similarly, there were no significant differences seen in the WOMAC and SF-12
scores (p=0.04). Still a quarter of our patients had significant disability with a HHS under 70
and the need for a walking aid in 5 patients. Surgeries (THA vs ORIF) averaged 152 vs 170
minutes with 992 vs 1128 mL average blood loss (p>0.05). There was an acceptable low rate
of major complications with no deep infections but one patient sustained a dislocation that was
treated in a brace successfully. The rate of hip replacement in the ORIF group was 8.7%.
Conclusion: Open Reduction and Internal fixation and total hip arthroplasty are both useful
techniques for treating acetabular fractures in older patients. Our results show that neither has
clear superiority. However, either technique used in the appropriate circumstance can be quite
successful.
230: Psychometric Analysis of Three Functional Outcome Scores in Tibial Plateau
Fractures using the Short Form-36, Short Musculoskeletal Functional Assessment and
Western Ontario and McMaster Osteoarthritis Index (WOMAC) Scores
Gerard Slobogean, BC; Rupen Dattani, BC; Peter J O'Brien, BC; Henry M Broekhuyse, BC;
Piotr A Blachut, BC; Kelly Ann Lefaivre, BC
Purpose: There are many general, orthopaedic, and injury specific functional outcome
measures available to the orthopaedic researcher. There is little guidance to which measure is
best to use in a particular population, and patients can easily be overwhelmed by the time and
burden of the collection of multiple functional outcome scores. We aimed to assess the utility
and responsiveness of the Short Form Physical Component Summary (SF-36 PCS), the Short
Musculoskeletal Function Assessment Dysfunction Index (SMFA DI) & the Western Ontario
McMaster Osteoarthritis Index Physical Function (WOMAC PF) in patients treated operatively
for tibial plateau fractures.
Method: A prospective study between 2005 and 2010 evaluating 55 patients who underwent
open reduction and internal fixation for isolated unicondylar split depression tibial plateau
fractures. Patients were asked to complete the SF-36, SMFA and WOMAC questionnaires at
baseline, 6 months and 12 months post surgery.Correlation between functional outcome
measures were calculated using intra-calss correlations. Responsiveness was tested using
Standard Response Mean (SRM) , which is the mean score change divided by the standard
deviation (SD) of the score change between each time period. The difference in standardized
change scores for the SF-36 PCS, SMFA DI and WOMAC PF from 6 to 12 months was
compared using a paired t-test. In addition, responsiveness was evaluated comparing number
of patients who attained a minimally clinically important difference (MCID), and floor and ceiling
effects (10% at lowest or highest level of functioning).
Results: The SF-36 PCS, SMFA DI and WOMAC PF scores were highly correlated at
baseline, 6 months and 12 months post surgery. The standard response mean (SRM) for the
SF-36 PCS was statistically higher than the SRM for the SMFA DI or the WOMAC PF. There
was no statistical difference between the SRM for the SMFA DI and the WOMAC PF.
Significantly more patients were found to have a minimal clinically important change, between
6 and 12 months post surgery, based on the SF-36 than the other two functional scores. There
was no floor effect found on any of the 3 functional scores evaluated; however, a significant
ceiling effect was noted with the WOMAC PF but not with the SF-36 PCS or the SMFA DI.
Conclusion: In patients with tibial plateau fractures, all three of these functional outcome
score are highly correlated, and the SMFA DI and WOMAC PF have a significant ceiling effect
at one year. However, the SF-36 PCS is more responsive than the SMFA DI and WOMAC PF.
These results, along with the usefulness of the SF-36 for comparing disease burden across
populations, recommend the SF-36 as the instrument of choice in assessing functional
outcome in patients with tibial plateau fractures.
231: Radiographic Identification of Atypical Subtrochanteric and Femoral Shaft
Fractures
Lise A Leveille, BC; Penny Brasher, BC; Pierre Guy, BC; Peter J O'Brien, BC
Purpose: Atypical subtrochanteric (ST) and femoral shaft (FS) fractures have been
increasingly reported in the literature. Their association with long-term bisphosphonate use has
been debated. Smaller case series and case-control studies have suggested an association
between atypical ST/FS fractures and long-term bisphosphonate use. Some larger, population
based studies have not supported this association. In the majority of these larger studies no
radiographic review was completed. The purpose of this study was to first, identify the
proportion of atypical fractures in patients admitted to a level one trauma center with a lowenergy ST/FS fracture using the American Society of Bone and Mineral Research (ASBMR)
radiographic criteria. Second, to quantify the inter-observer reliability of using this method for
identification of atypical ST/FS fractures. Finally, to identify the proportion of atypical ST/FS
fracture subjects with a history of bisphosphonates exposure.
Method: A prospectively collected trauma database was used to identify patients greater than
55 years of age presenting to a level one trauma center with a low-energy ST/FS fracture
between January 2000 and February 2011. Exclusion criteria were clinical or radiographic
evidence of active malignancy, peri-prosthetic fracture, history of metabolic bone disease, or
fracture outside the defined region of interest. Digital radiographs were assessed by three
blinded, independent reviewers and categorized as either atypical or non-atypical based on the
ASBMR radiographic criteria for atypical ST/FS fractures. A chart review was completed on all
atypical fractures.
Results: Three hundred and fifty eight ST/FS fractures were identified. Exclusion criteria were
met in 195 fractures. Thirty-nine fractures were radiographically categorized as atypical, with
an inter-rater reliability (concordance) of 96% and Kappa of 0.92. Of the atypical ST/FS
fractures, ten were excluded after chart review for history of metastatic cancer, high-energy
mechanism of injury, or Paget’s disease. Of the remaining 29 atypical fractures in 26 subjects,
86% were taking a bisphosphonate at the time of fracture. The average duration of
bisphosphonate use was 8.2 years.
Conclusion: The majority of low-energy ST/FS fractures are not atypical fractures according
to the ASBMR radiographic criteria. Use of database identified cohorts, without radiographic
review, results in over inclusion and masking of any association between atypical femoral
fractures and long-term bisphosphonate use. Three independent reviewers using the ASBMR
radiographic criteria is a reliable means of identifying atypical ST/FS fractures. In this series of
atypical ST/FS fractures, the majority had a history of bisphosphonate exposure, which is
consistent with previously reported case series.
232: The Incidence and Influence of Distal Ulnar Fractures on Outcomes of Distal Radial
Fractures in Women 50 years and Older
Geoffrey Johnston, SK
Purpose: To determine the incidence of distal ulnar fractures, to characterize them as to their
location and to identify their influence of clinical and radiographic outcomes of closed
management of distal radial fracture management.
Method: Radiographs from 221 women 50 years and over who had undergone closed
reduction of a distal radial fracture were evaluated as to the presence of an associated distal
ulnar fracture. It, in turn, was assessed as to its location: styloid tip, styloid base, or ulnar neck.
The influence of a distal ulnar fracture on three radiographic features (radial inclination, ulnar
variance and tilt was assessed, as was its influence on the outcomes of the patient rated wrist
evaluation (PRWE) and grip strength.
Results: Of 221 distal radial fractures treated by closed reduction and cast management, there
were 158 fractures of the distal ulna were identified, for an incidence of 71%. Thirty-seven
percent of distal ulnar fractures involved the distal styloid process, 55% the base of the styloid.
There were 13 fractures of the ulnar neck, representing 8% of distal ulnar fractures. Distal
ulnar fractures, whether styloid tip or basal did not influence either the radiographic or clinical
outcomes (PRWE and grip strength) of distal radial fractures when compared to those patients
in whom there was no distal ulnar fracture. In the presence of an ulnar neck fracture radial
fracture settling, reflected by a diminishing degree of radial inclination, the outcome differed in
this group. Whereas end-point radial inclination averaged 19 degrees in the 221 patients,
radial inclination averaged 24 degrees in the setting of an ulnar neck fracture.
Conclusion: Distal ulnar fractures are associated with distal radial fractures in as many as
70%. Ulnar neck fractures appear to protect against radial settling.
233: Tibial Nail Distal Positioning: A Radiographic Study
Travis E Marion, ON; Steven R Papp, ON; Wade T Gofton, ON; Allan Liew, ON
Purpose: Intramedullary fixation is the treatment of choice for diaphyseal tibial fractures. The
importance of the proper insertion point is well established. Intramedullary fixation of distal
tibial fractures relies upon the placement of the guidewire distally to achieve and maintain an
acceptable reduction once the intramedullary nail has been inserted. Inappropriate distal
positioning of the guidewire may contribute to malalignment when the nail is inserted, leading
to malunion, ankle joint dysfunction, and early arthritic changes. The ideal distal position of the
guidewire in the distal tibia has yet to be well defined. It was our hypothesis that the ideal
guidewire endpoint is lateral to the centre of the ankle joint.
Method: Twenty intact tibial radiographs were selected and evaluated. The centre of the
medullary canal at the level of the isthmus was established and extended inferiorly through the
ankle joint on antero-posterior (AP) and lateral radiographs. Transverse lines of reference on
the AP and lateral views were established. The position in which the isthmic line intersected
these reference lines was measured and expressed as a percentage from medial to lateral on
the AP view and posterior to anterior on the lateral view.
Results: AP Radiograph Reference Line Percent From Medial Cortex Maximal Metaphyseal
Width 62.0 ± 3.9% Tibial Articular Width 66.5 ± 7.9%Talar Width 63.8 ± 7.8% Lateral
Radiograph Reference Line Percent From Posterior Cortex Maximal Metaphyseal Width 42.3 ±
5.3% Tibial Articular Width 37.7 ± 10.6%
Conclusion: The ideal placement of the guidewire in the distal tibia for intramedullary fixation
of the tibia is not well defined. Traditional teaching usually calls for placement of the guidewire
endpoint in the ``centre`` of the ankle joint or distal tibia. Our findings show that the ideal
endpoint for an intramedullary nail is lateral and posterior to the centre of the distal tibia
articular surface or talus. Positioning of the nail in the ``centre`` may shift the axial position of
the talus and contribute to a malreduction, especially in the setting of distal comminution. This
study supports further investigations to determine the effect of distal tibial nail malposition and
its clinical significance.
234: Vacuum Assisted Closure (VAC) Effects on Skeletal Muscle After Compartment
Syndrome in an Animal Model
Geoffrey P Wilkin, ON; Shiemaa Khogali, ON; Shawn Garbedian, ON; Brad Slagel, ON;
Wade T Gofton, ON; Allan Liew, ON; Jean Marc Renaud, ON; Steven R Papp, ON
Purpose: Compartment syndrome is a potentially limb-threatening condition, and residual
morbidity may result even with timely fasciotomy. The use of a Vacuum Assisted Closure™
(VAC) device on fasciotomy wounds has been advocated. The effects on the underlying
muscle are largely unknown. The purpose of the present study was to evaluate the effects of
VAC therapy on skeletal muscle after fasciotomy for compartment syndrome. It was
hypothesized that by increasing blood flow to the affected area and by clearing excess
intracompartmental fluid, the VAC device would be protective against ongoing muscle fiber
damage and would improve the regeneration of damaged fibers after fasciotomy.
Method: Compartment syndrome was induced in the hindlimb of 20 young adult female pigs
using a previously validated protocol (infusion of porcine serum and continuous compartment
pressure monitoring). Fasciotomy was performed after six hours and animals were randomized
to receive either wet-to-dry dressings (non-VAC) or VAC dressings for 7 days, followed by
delayed primary wound closure. The peroneus tertius muscle (the largest anterior
compartment muscle in pigs) and the healthy contralateral muscle were harvested after one
week or three weeks for analysis.
Results: At one week, compared to the unaffected side, muscle weights were 130% greater
for the VAC treated muscles, and 93% greater for non-VAC treated muscles. This suggested
more fluid accumulation in the VAC treated muscles. Histological measurements showed less
than 2% of the total cross-sectional area had exclusively intact muscle fibers. Most of the
observed sections contained either intact fibers surrounded by mononucleated cells or only
mononucleated cells (i.e. no intact fibers). VAC treated muscles had a greater surface area
containing only mononucleated cells compared to non-VAC treated muscles. At 3 weeks, the
weights exceeded the unaffected side by 26-27% and intact fibers constituted 80% of the total
surface area examined in both treatment groups. Within those areas, VAC-treated muscles
showed a greater proportion of mononucleated cells between fibers than in non-VAC treated
muscles.
Conclusion: VAC and non-VAC treated animals show initial muscle fiber damage in a
compartment syndrome model. This showed improvement after 3 weeks. In this model, VAC
treatment did not appear
235: A Novel Process for Anatomic Measurement of the Proximal Ulna to Guide
Prosthesis Design
Ian Pereira, ON; Bashar Alolabi, ON; Alia Gray, ON; George S Athwal, ON; James A Johnson,
ON; Graham JW King, ON
Purpose: Deficiency of the articular surface of the proximal ulna as a consequence of
fractures may lead to elbow instability and post-traumatic arthritis. However, there are currently
no available implants to address isolated bony deficiencies of the proximal ulna. Although total
elbow replacement is an option, current elbow prostheses do not perform as reliably as
prostheses of other joints. A better understanding of the precise morphology of the articular
surface of the proximal ulna should assist in the development of improved designs of both
partial and total elbow joint prostheses. The aim of this study was to develop a novel technique
to better characterize the morphology of the proximal ulna to guide improved prosthetic
designs.
Method: Thirty-two cadaveric elbows were imaged by computed tomography, segmented into
a 3-dimensional reconstruction of the proximal ulna using Mimics medical image processing
software, and imported into Solidworks 3D engineering measurement and design software.
Custom software interfaced with Solidworks allowed accurate and efficient identification and
measurement of characteristics of 66 significant articular features of the greater sigmoid notch,
coronoid, and olecranon of each specimen.
Results: The average coronoid guiding ridge radius of curvature was greater than that of the
olecranon (10.8+/-2.0mm, 9.9+/-1.9mm, p=0.2). The angle of the coronoid guiding ridge to the
total guiding ridge was medially rotated with respect to the angle of the olecranon guiding ridge
to the total guiding ridge (10.9+/-7.2 degrees, -9.8+/-7.7 degrees, p<0.05). The coronoid height
was larger than the olecranon height (16.5+/-2.2mm , 7.7+/-1.3mm, p<0.05). The bare area
width was 5.5+/-2.0mm, and the surface length was 5.7+/-1.9mm. The coronoid medial
articular surface was concave compared to the convex lateral facet, although the surface
angles of both increased to a maximum at 50% of the coronoid height from the tip before
decreasing to a minimum at the coronoid base. The rate of increase of coronoid depth below
50% of the coronoid height was less than that above 50% (0.17+/-0.01mm/%, 0.42+/0.2mm/%, p<0.05).
Conclusion: Prostheses of the elbow have been limited in their performance, in part due to a
lack of understanding of the anatomic complexity of the proximal ulna. This study described an
effective and efficient process to better characterize significant anthropometric features of the
proximal ulna. This data has recently been used to design a novel coronoid prosthesis. Future
studies are planned to further assess the performance of this prosthesis and design improved
implants for replacement of the proximal ulna.
236: Anatomical Repair of the Distal Biceps Tendon May not be Possible Through a
Single Anterior Incision
Greg W Hansen, ON; J W Pollock, ON; Joel M Werier, ON; Kawan Rakhra, ON; Steven R
Papp, ON
Purpose: The biceps muscle is an important flexor and supinator of the elbow. When distal
biceps tendon ruptures occur, surgery is often performed in order to restore normal strength.
The single incision approach has gained significant popularity and it is commonly used in our
institution. Through a single anterior incision, the radius is exposed and the tendon is repaired
to the bicipital tuberosity using suture anchors. However, the anatomic footprint of the biceps
tendon is located ulnar on the bicipital tuberosity. This makes an anatomic repair difficult
through this approach. We hypothesized that an anatomic repair of the distal biceps tendon
cannot be consistently achieved utilizing a single anterior approach with suture anchors.
Method: Twenty-seven retrospective, post-operative CT scans were obtained on patients’
operative elbows that had biceps tendon repairs performed using a single anterior incision and
suture anchor fixation. Using axial images of the distal radius, the sagittal axis of the radius
was determined, and the position of the bicipital tuberosity apex was referenced relative to this
axis. In a similar fashion, the position of both the proximal and distal suture anchors
(representing the site of tendon repair) was measured and referenced from the tuberosity
apex.
Results: All patients were male with an average age of 47 years (range 35 – 66). There were
13 left sided and 14 right sided repairs. The apex of the bicipital tuberosity was located ulnar
from the mid-sagittal radial axis an average of 55.6 degrees (range 43-67 deg). The proximal
anchors were positioned radially from the tuberosity apex an average of 52.5 degrees (range 6
– 98 deg) while the distal anchors were positioned radially by 50.4 degrees (range 12 – 117
deg).
Conclusion: In this group of patients who had undergone suture anchor repair through a
single incision technique, the distal biceps tendon was commonly repaired to a nonanatomic
position on the bicipital tuberosity. The repair was often positioned radial from the bicipital
tuberosity apex. This could lead to significant weakness, particularly with supination. When
performing a biceps repair through a single incision technique, surgeons should pay attention
to the position of the repair site. In some cases, it may not be possible to anatomically repair
the biceps tendon to the ulnar aspect of the bicipital tuberosity through a single incision
approach. Further strength testing and validated outcome scores are required to determine if
this malpositioning results in a clinically detectable deficit.
237: Comparing the Extensor Digitorum Communis Splitting Approach to the
Posterolateral Kocher Approach: A Novel Method of Measuring Articular Surface area
William Desloges, ON; Hakim Louati, ON; Steven R Papp, ON; J W Pollock, ON
Purpose: Currently, the most widely used lateral approach to the elbow is the posterolateral,
or Kocher approach. It is believed that the extensor digitorum communis (EDC) splitting
approach allows easier access to the more commonly fractured anterior hemisphere of the
radial head while minimizing the risk of injuring the lateral ulnar collateral ligament. The aim of
this cadaveric study was to compare the visible bony and articular surface area procured by
the EDC splitting, and the posterolateral Kocher approaches. Secondarily, we aim to compare
the extended EDC splitting approach to the extended Kocher approach.
Method: The following approaches were concurrently performed on six fresh frozen cadaveric
upper extremities: the EDC splitting approach, the Kocher approach, and the extensile EDC
splitting approach. The extensile Kocher approach was also performed on four specimens. The
visible bony and articular surface areas were outlined using a burr for each approach. Then,
bones were stripped of all soft tissues for analysis. Each bone was converted into a digitized
3D model using the DAVID Laserscanner system (Koblenz, Germany). Using the markings
created by the burr, the visible surface area obtained for each approach was mapped and
quantified.
Results: The EDC splitting approach provided a greater percentage of visible surface area to
the anterior half of the radial head as compared to the Kocher approach (median 100% and
68%, respectively; p = 0.03; Wilcoxon signed-ranks test). The anterolateral quadrant of the
radial head was equally well visualized with both the Kocher and EDC splitting approaches.
The extended Kocher and extended EDC splitting approaches procured comparable
visualization of the distal humerus, the radial head and coronoid process.
Conclusion: Although the EDC splitting and Kocher approaches both adequately exposed the
commonly fractured anterolateral quadrant of the radial head, the EDC splitting approach
offered a significantly greater exposure to the whole anterior half of the radial head. Therefore,
we recommend using the EDC splitting approach to reliably visualize fracture lines, in the
reduction and fixation of partial articular radial head fractures. Furthermore, using the EDC
splitting approach minimizes the risk of injuring the ulnar lateral collateral ligament, which is a
primary constrain to posterolateral rotatory instability.
238: Distal Humerus Hemiarthroplasty: The Effect of Implant Sizing on Elbow Joint
Kinematics
Sagar J Desai, ON; George S Athwal, ON; Louis M Ferreira, ON; James A Johnson, ON; Mark
Welsh, ON; Emily Lalone, ON; Graham J W King, ON
Purpose: Distal humeral hemiarthroplasty is a novel treatment for distal humerus fractures,
non-unions and avascular necrosis. The biomechanical effects, however, have not been
reported. The purpose of this in vitro study was to quantify the effects of distal humeral
hemiarthroplasty and implant size on elbow joint kinematics.
Method: Eight fresh-frozen cadaveric arms were mounted in an elbow testing system, which
simulated active and passive flexion in the dependent, horizontal, varus and valgus positions.
Kinematic data, including varus-valgus angulation and ulnohumeral rotation, were obtained
using an optical tracking system. An olecranon osteotomy was performed to access the joint
and a custom distal humeral stem was implanted under image-guided navigation. Three
humeral spools were evaluated for kinematics: the optimal sized spool, under-sized and oversized. Statistical analysis was performed using repeated measures analysis of variance.
Results: Hemiarthroplasty altered joint kinematics, regardless of implant size during both
active and passive motion. In the valgus position, the optimally sized implant resulted in a
mean increase in valgus angulation of 3.5º ± 1.7º (p < 0.05) as compared to the native elbow.
In the varus position, the optimal and undersized implants both resulted in significant (p < 0.05)
increases in varus angulation, 2.6º ± 1.4º and 3.2º ± 1.2º, respectively. The under-sized
implant had the greatest alteration in kinematics while the over-sized implant best reproduced
kinematics of the native elbow. In the varus position, during active and passive motion,
kinematics of the over-sized implant were not significantly different from the native elbow (p >
0.05).
Conclusion: An optimally sized distal humeral hemiarthroplasty caused significant increases
in varus-valgus laxity and ulnohumeral rotation. This could be secondary to differences in the
shape of the humeral implant relative to the native elbow. The under-sized implant
demonstrated the greatest alteration in kinematics, while the over-sized implant best
reproduced native elbow kinematics. This suggests that when uncertainty exists in size
selection, the larger implant may be better at increasing post-operative stability. Future
hemiarthroplasty studies are required to determine optimum articular contact, joint forces, and
implant articular shape.
239: Measurements of the Ispilateral Capitellum can Reliably Predict the Diameter of the
Radial Head
Alexandre Leclerc, QC; Sagar J Desai, ON; Simon Deluce, ON; Louis Ferreira, ON; Graham
JW king, ON; George S Athwal, ON
Purpose: Presently, there is no validated method to determine the correct diameter of a radial
head implant when the radial head is too comminuted to function as a template, or during
revision surgery when the native radial head has been previously excised. The purpose of this
CT-based morphology study was to determine if ipsilateral capitellar dimensions could be used
to predict the diameter of a radial head implant.
Method: Computed Tomography (CT) scans of 30 elbows were used to generate three
dimensional (3D) models of the humerus and radius in MimicsTM (Materialise). Measurements
of the radial head included the maximum diameter (Dmax), the minimum diameter (Dmin) and
the diameter of the articular dish (Ddish). Measurements of the distal humerus included the
width of the capitellum (CAPwidth), and the width from the lateral aspect of the capitellum to
the lateral trochlear ridge (CAPridge). Pearson bivariate correlations were determined between
humeral and radial head dimensions.
Results: The mean radial head dimensions were Dmax = 24.2±2.5 mm, Dmin = 22.9±2.4 mm
and Ddish = 18.0±2.2 mm. The mean capitellar measurements were CAPwidth = 18.0±1.4 mm
and CAPridge = 22.5±2.3 mm. The most significant correlations were found between Dmax
and CAPridge (r=0.922, p<0.001), Dmin and CAPridge (r=0.906, p<0.001), and Ddish and
CAPwidth (r=0.784, p<0.001).
Conclusion: Measurements of the ispilateral capitellum appear to be useful in the estimation
of native radial head diameter. The CAPridge width was very strongly correlated with the
maximum and minimum diameters of the radial head and was superior to the CAPwidth. This
suggests that CAPridge width may be useful to accurately predict the native radial head
diameter. These morphological relationships could be plotted to produce an implant selection
chart for radial head sizing applicable to any implant system. The CAPridge width, measured
from the lateral aspect of the capitellum to the trochlear ridge, can be measured preoperatively on a CT scan, or intra-operatively using a ruler or callipers. Thus, measurements of
the ispilateral capitellum can be used to reliably estimate the diameter of the native radial head
and therefore should allow the surgeon to more accurately predict the optimal diameter of a
radial head implant in the circumstances where the native radial head is either unavailable or
unsuitable to assist with implant sizing.
240: Radial Head Instability Following Malreduction of the Proximal Ulna: A
Biomechanical Assessment
Emilie Sandman, QC; Fanny Canet, QC; Yvan Petit, QC; G Yves Laflamme, QC; George S
Athwal, ON; Dominique M Rouleau, QC
Purpose: Malreduction of the ulna following proximal ulnar fractures, such as Monteggia
injuries, may lead to arthrosis and instability. Malunion of the proximal ulna dorsal angulation
(PUDA) has been implicated in malalignment of the radiocapitellar joint. Thus, the purpose of
this biomechanical study was to evaluate the magnitude of ulnar malreduction at the PUDA
that would be necessary to cause radial head instability, with and without a simulated annular
ligament injury.
Method: Six fresh frozen upper extremities were mounted on a motorized elbow motion
simulator. To reproduce a proximal ulnar fracture, an osteotomy at the PUDA site was
completed on each specimen. Fixation of the osteotomy was conducted with 5 variable angle
plates (-10°, -5°, 0°, 5°, 10°) to reproduce malunions. Lateral elbow radiographs were taken
with fluoroscopic assistance in 4 elbow positions (maximal extension, 45°, 90°, maximal
flexion) and three forearm positions (neutral, pronation, supination). The protocol was initially
done with the annular ligament intact and was repeated after a simulated annular ligament
injury. Radial head instability was measured as a ratio of the displacement of the radial head
on the capitellum, and was termed the Radio-Capitellum Ratio (RCR).
Results: Significant interactions exist between elbow positions, angles of malunion and
annular ligament integrity when evaluating radial head stability with the RCR measurement
(p<0.001). With increasing extension malunion of the proximal ulna, the radial head
progressively translates anteriorly on the capitellum (p=0.002), with the mean displacement
ranging from 11% to 14% when the annular ligament is intact and from 23% to 57% with the
annular ligament sectioned. The greatest ratios of radiocapitellar instability where seen when
the annular ligament was sectioned (p<0.001). Anterior translation of the radial head also
increased as the elbow moved from extension to flexion (p<0.001). The mean radial head
displacement was 70% when the elbow was in maximal flexion, reduced at -10° and with the
annular ligament ruptured.
Conclusion: Malalignment of the proximal ulna directly affects elbow biomechanics and
stability, especially the radial head when the annular ligament is insufficient. Thus, this study
demonstrates the importance of anatomic alignment of the proximal ulna, particularly
recreation of the proximal ulna dorsal angulation, to ensure correct radiocapitellar
relationships.
241: Reliability of the Modified Mason Classification for Radial Head Fractures - A
Comparison of Plain Radiographs versus CT
Michael Gladwell, ON; Yishai Rosenblatt, IR; George S Athwal, ON; Ruby Grewal, ON;
Graham JW King, ON; Kenneth J Faber, ON
Purpose: Radial head fractures are commonly classified using the Broberg and Morrey
modification of the Mason classification (modified Mason classification), a radiograph-based
system that has been found to have moderate inter-observer reliability that can be improved
with the addition of external rotation oblique radiographs. The reliability of the modified Mason
classification using computed tomography has not been established. We hypothesized that CT
scan, including 3D reconstruction, would improve inter- and intra-observer reliability of the
modified Mason classification.
Method: Fifty-four patients with acute radial head fractures were included in the study. All had
AP and lateral radiographs and a CT scan with 3D reconstructions. Twenty-four had a
Greenspan radial head-capitellum view. Five observers (two orthopaedic residents, two upper
extremity orthopaedic fellows, and an upper extremity surgeon) classified each case according
to the modified Mason classification. Cases were classified four times, based on the AP and
lateral, AP/lateral and Greenspan, CT scan, and 3D reconstruction. Four of the observers
repeated the classification one week later. Fleiss’ kappa values for inter-observer reliability,
and Cohen’s kappa values for intra-observer reliability were calculated. Values were compared
among different imaging types and observers using a one-way ANOVA.
Results: The kappa values for inter-observer reliability based on AP and lateral, AP/lateral and
Greenspan, CT, and 3D reconstruction were 0.46 (95% CI 0.40-0.52), 0.35 (0.25-0.44), 0.42
(0.36-0.48) and 0.42 (0.36-0.48) respectively. The kappa values for intra-observer reliability
were 0.67 (0.58-0.76), 0.64 (0.50-0.79), 0.63 (0.53-0.73) and 0.64 (0.55-0.73) respectively.
There was no significant difference in inter-observer reliability among imaging techniques, and
no difference in intra-observer reliability among imaging techniques or observers (p>0.05).
Conclusion: The inter-observer reliability of the modified Mason classification was moderate
and the intra-observer reliability was moderate to substantial according to the criteria of Landis
and Koch. Level of training did not affect the intra-observer reliability. The results of this study
are comparable to previous studies using plain radiographs. CT scan and 3D reconstruction
did not improve inter- or intra-observer reliability. The additional detail offered by CT often
made classification more difficult, since this extra detail does not fit into the modified Mason
classification. The CT helps to better understand the fracture pattern, especially type two and
three fractures, which often have multiple small fragments, however further studies are needed
to determine whether this additional information improves patient outcomes. Further
modification of the classification, based on CT, may improve reliability and help direct
treatment.
242: The Lateral Paraolecranon Approach for Total Elbow Arthroplasty
Alexis Studer, ON; George S Athwal, ON; Joy C MacDermid, ON; Kenneth Faber, ON;
Graham JW King, ON
Purpose: The purpose of this study was to describe and evaluate the lateral paraolecranon
approach, a modification of a triceps splitting approach, for total elbow arthroplasty (TEA) and
to compare it to the paratricipital and triceps splitting approaches.
Method: This study evaluated 34 patients that underwent TEA; 25 with rheumatoid arthritis (28
elbows) and nine fracture cases. Of the 28 elbows with RA, 17 underwent a triceps splitting
approach, six a lateral paraolecranon and five a paratricipital approach. Of the nine fracture
cases, five patients underwent a lateral paraolecranon approach and four were operated
through a paratricipital approach. Extension strength, range of motion, elbow function (Mayo
Elbow Performance Index), and complications related to triceps insufficiency were compared
for all three approaches. Additionally, the lateral paraolecranon and paratricipital approaches
were compared to the contralateral healthy elbow in the nine fracture cases.
Results: Patients with rheumatoid arthritis had better extension torque when the prosthesis
was implanted through the lateral paraolecranon approach (20.1±7.6 Newton-meters), when
compared to the triceps splitting approach (13.1± 4.3 N-m) or the paratricipital approach
(12.3±6.2 N-m) (p< 0.01). The elbow extension strength according to the MRC scale was
significantly higher for the groups where the triceps was not detached (paratricipital and lateral
paraolecranon approach) when compared to the triceps splitting approach (p<0.05 and p<
0.001, respectively). There was one case of triceps insufficiency in the triceps-splitting group
and none in the paratricipital or lateral paraolecranon approaches. In the fracture group, the
extension strength of the replaced elbow was similar to that of the contralateral normal elbow
with both the paratricipital and lateral paraolecranon approaches. Patients with rheumatoid
arthritis who had a triceps splitting approach had less extension (43.7º±16º) than those who
had a lateral paraolecranon (15.8º±12.1º) or triceps-on approach (23.6º±10.3º) (p<0.05). There
were no differences in flexion range in patients with rheumatoid arthritis (p>0.05). There was
no effect of the surgical approach on both flexion and extension range in the fracture group
(p>0.05). The average MEPI score for the patients with R.A. (86.4±11.7 points) was not
significantly different (p=0.63) from the group with traumatic conditions (89.4±15.9 points).
Conclusion: The lateral paraolecranon approach can provide equal or better strength and
functional outcomes, in comparison to more traditional elbow approaches. The lateral
paraolecranon approach avoids triceps tendon detachment and repair to the olecranon,
thereby reducing the risk of triceps insufficiency while maintaining extension strength. The
lateral paraolecranon approach allows for improved ulnar visualization when compared to the
paratricipital approach; however, ulnar visualization is still compromised when compared to
other triceps detaching/reflecting approaches.
243: Ulnar Placement of the Distal Biceps Tendon During Repair Improves Supination
Strength - A Biomechanical Analysis
Marc Prud'homme-Foster, ON; JW Pollock, ON; Hakim Louati, ON; Steven R Papp, ON
Purpose: Repair of distal biceps tendon rupture requires reestablishing its insertion site on the
radial tuberosity. Based on anatomical studies it has been suggested that the heads should be
inserted on the ulnar aspect of the footprint. The effect of insertion repair site on the footprint
has not previously been studied. This study examines the effect of the repair site on forearm
supination strength, and provides biomechanical evidence for ideal insertion placement.
Method: Twelve fresh-frozen cadaveric arms were secured using an in vitro elbow simulator
and a two-head repair was performed in ulnar and radial locations on the radial tuberosity.
Isometric supination torque and elbow flexion force were recorded with the forearm in 45
degrees supination, neutral rotation and 45 degrees pronation.
Results: In all specimens elbow flexion strength was not affected by - biceps repair in the
ulnar or radial configuration on the tuberosity. Forearm supination was significantly stronger
with a more ulnar insertion placement on the tuberosity. While the difference in was less
pronounced in pronation, radial placement resulted in a mean drop of 78% (p<0.05) in
supination strength with the arm in 45 degrees of supination.
Conclusion: Studies of the distal biceps tendon insertion sites have suggested a welldescribed footprint on the radial tuberosity. The effect of the repair site on supination strength,
to our knowledge, has never been studied. This biomechanical study suggests that insertion
site placement on the tuberosity affects forearm strength. A more ulnar repair site on the
tuberosity resulted in improved supination strength. This highlights the importance of achieving
an ulnar distal biceps tendon repair.
244: Validity of Magnetic Resonance Imaging in Detecting Biceps Pathology
Simon Fournier-Gosselin, QC; Helen Razmjou, ON; Richard Holtby, ON
Purpose: Role of MRI in detecting long head of biceps (LHB) pathology has been questioned
by previous studies, in which biceps pathology was examined in patients with general shoulder
pain or rotator cuff tears. The purpose of present study was to examine the accuracy of MRI in
detecting biceps pathology as the primary finding in patients who had arthroscopic evidence of
pathology in the biceps tendon.
Method: Prospectively collected surgical data were extracted from a research based database
in which biceps pathology was classified as partial tear, dislocation /subluxation, or complete
rupture. The MRI was conducted in the same institute where the surgery was performed. All
images had been interpreted by one of three radiologists with training in musculoskeletal
disorders. The data extraction form that categorized MRI findings was extracted by an
orthopedic fellow from the electronic MRI report. Associated pathologies in rotator cuff and or
labrum were reported for descriptive purposes. Sensitivity, specificity and likelihood ratios were
calculated.
Results: Data of 116 patients with biceps pathology [77 men (66%), mean age=63, range 3784)] who had undergone arthroscopic surgery over a period of 6 years were used for analysis.
Prevalence of complete biceps rupture was 36 % in all patients with documented biceps
pathology. Prevalence of partial thickness biceps tears and subluxation/dislocation was 75%
and 9% respectively. Superior labral pathology had a prevalence of 30% (15% SLAP type I,
12% type II, and 3% type III) with 79% (92) of patients having a full thickness tear of rotator
cuff. Sensitivity (true positives rate) of MRI was 0.39 for full rupture and specificity (true
negative rate) was 0.98. Sensitivity and specificity were 0.16, and 0.80 for partial thickness
tears, and 0.89 and 0.84 for dislocation and or subluxation respectively. Positive Likelihood
Ratio and negative Likelihood Ratios were 16 (large change in probability of having a
pathology) and 0.63 (insignificant change) for full ruptures, 0.82 and 1.04 (insignificant change)
for partial thickness tears, and 5.59 and 0.13 (moderate change) for dislocation/subluxation.
Conclusion: MRI is a highly specific diagnostic test for ruling in a full-thickness biceps tear but
is not a sensitive tool for ruling out a full biceps tear. Subluxation/dislocation of the biceps can
be moderately ruled in and ruled out. Partial-thickness tears of the biceps tendon are not
reliably diagnosed with MRI.