Uncemented Total Hip Arthroplasty With Subtrochanteric

The Journal of Arthroplasty Vol. 14 No. 6 1999
U n c e m e n t e d Total Hip A r t h r o p l a s t y With
Subtrochanteric D e r o t a t i o n a l O s t e o t o m y
for Severe F e m o r a l A n t e v e r s i o n
H a m i d G. Z a d e h , F R C S ( O r t h ) , Jia H u a , M D , P h D , P e t e r S. W a l k e r , P h D ,
a n d S a r a h K. M u i r h e a d - A l l w o o d , FRCS, BSc
Abstract" Total hip joint arthroplasty (THA) in the presence of severe femoral anteversion
(>50 °) is technically demanding. This problem is often encountered in patients with
osteoarthritis secondary to hip joint dysplasia or congenital dislocation. We describe a
method of THA in which an uncemented femoral prosthesis is used in conjunction with
subtrochanteric derotational osteotomy. This technique allows the restoration of the
normal proximal femoral anatomy, induding the abductor muscle lever arm without
resorting to greater trochanteric transfer. Correction of the excessive femoral anteversion
avoids the tendency for postoperative anterior instability. The osteotomy site may also serve
as the site for femoral shortening or angular correction when required, which preserves the
normal femoral flare. The prostheses used were custom CAD/CAM (computer-assisted
design/computer-assisted manufacturer) in design and had the following features: a close
intramedullary proximal fit, with collar, lateral flare, and hydroxyapatite coating to achieve
early proximal fixation, and longitudinally cutting fluted stem to provide immediate
rotational stability across the osteotomy site. Although we used CAD/CAM custom
prostheses, off-the-shelf uncemented hip prostheses with similar design features have
become available. We report on 7 patients who underwent THA using this technique. The
average patient age was 49 years (range, 34-61 years) with a mean follow-up period of 31
months (range, 16-60 months). To date, all cases have had a satisfactory outcome with
evidence of union at the osteotomy site. Harris hip scores improved from an average of 44
preoperatively to 91 by the end of follow-up period. One case was complicated by delayed
union at the osteotomy site, which was successfully corrected with bone grafting and
temporary plate stabilization. Key words: Total hip joint arthroplasty, femoral anteversion,
hip joint dysplasia, osteoarthritis, subtrochantefic derotational osteotomy, uncemented
fixation, CAD/CAM prostheses.
is often associated with congenital dislocation of the
hip (CDH) or acetabular dysplasia. The surgeon
faces a number of technical problems when contemplating arthroplasty in these circumstances (Fig. 2).
The abnormal upper femoral anatomy often necessitates the use of miniature or custom-made prostheses [2--4,6,7]. Femoral prosthesis insertion without
correction of the excessive anteversion may result
in postoperative anterior dislocation [7]. Furthermore, the likely eccentric loading of the acetabular
component may lead to component toggle and early
aseptic loosening.
Hip joint osteoarthritis in the presence of severe
femoral anteversion is not easily amenable to
surgical correction (Fig. 1) [1-6]. This condition
From the Royal National Orthopaedic Hospital Trust and the Centre
for Biomedical Engineering, Stanmore, Middlesex, England.
Funds were received from the Arthritisand Rheumatism Council,
UK in support of the research material describedin this article.
Submitted May 15, 1998; accepted January 28, 1999.
Reprint requests: Hamid G. Zadeh, FRCS(Orth), 59 Apsley
House, Finchley Rd, London NW8 0NY, England.
Copyright © 1999 by Churchill Livingstone®
0883-5403/9911406-0008510.00/0
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Zadeh et al.
683
A
Fig. 1. (A) Schematic representation of normal and excessive femoral anteversion in adults. The diagram on the left
demonstrates normal femoral anteversion (10°-20°); the middle, excessive anteversion; and the right, excessive
anteversion with the femoral head and neck removed as seen during a hip replacement. (B) A computed tomography scan
demonstrating excessive femoral anteversion on the left side. (Modified from Holtgrewe and Hungerford [7], with
permission.)
In cases with a high false acetabulum, restoration
of the n o r m a l a n a t o m i c position of the acetabular c o m p o n e n t is generally r e c o m m e n d e d [81. In
these cases, s i m u l t a n e o u s femoral shortening is
required to avoid sciatic n e r v e injury by excessive
traction [4,6,9]. In severe femoral anteversion, the
greater t r o c h a n t e r is often displaced superiorly and
posteromedially [1,7]. Failing to restore the n o r m a l
offset m a y lead to i m p i n g e m e n t of the greater
t r o c h a n t e r on the pelvic wall a n d result in an
inefficient abductor lever a r m [7,10].
The traditional and most widely reported m e t h o d
of total hip joint arthroplasty (THA) in cases of CDH
or subluxation has b e e n the use of a transtrochanteric a p p r o a c h with c e m e n t e d implants [1-6,9].
During this procedure, o s t e o t o m y of the greater
t r o c h a n t e r is p e r f o r m e d ; the u p p e r f e m u r is
s h o r t e n e d to the desired length; a n d after insertion
of the femoral prosthesis and reduction of the
c o m p o n e n t s , the greater t r o c h a n t e r is wired onto
the f e m u r in a m o r e a n a t o m i c orientation. Alt h o u g h this technique offers excellent exposure of
the hip joint and allows s i m u l t a n e o u s correction of
the femoral length and the greater t r o c h a n t e r position, it has a n u m b e r of disadvantages. First, the
abductor insertion is violated during the trochanteric osteotorny, and this m a y result in abductor
weakness or greater trochanteric d e t a c h m e n t [2,3,9].
Second, excision of the i n t e r t r o c h a n t e r i c b o n e
mass and calcar during femoral shortening destroys
the p r o x i m a l f e m o r a l flare, and this r e m o v e s
the b e s t - q u a l i t y b o n e available for a c h i e v i n g
a stable p r o x i m a l fixation against torsional stresses,
especially w h e n using one of the latest-generation u n c e m e n t e d implants. We therefore looked for
a m e t h o d other t h a n the transtrochanteric approach.
We h a v e addressed these problems by using an
u n c e m e n t e d CAD/CAM (computer-assisted design/
computer-assisted m a n u f a c t u r e r ) custom femoral
prosthesis in conjunction with subtrochanteric derotational osteotomy. This technique allows easy correction of the a b n o r m a l position of the greater
trochanter, and the o s t e o t o m y level m a y also serve
as the site for femoral shortening or angular correction w h e n required. We report here our preliminary
experience with this operative technique and implant design.
Patients and Methods
Seven patients received a hip joint r e p l a c e m e n t of
this type during the period 1993-1997. The average
age of the patients was 49 years (range, 34-61
years), There w e r e 2 m e n and 5 w o m e n . The
original diagnosis in 6 patients was CDH and in 1
patient was childhood septic arthritis. In 2, the
dysplasia was associated with high dislocation and
in 5 cases with subluxation. According to Crowe's
classification [2], the joint dysplasia was graded as
grade I in 1 case, grade II in 4, a n d grade IV in 2.
Four of the 7 patients had previously u n d e r g o n e
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The Journal of Arthroplasty Vol. 14 No. 6 September 1999
Fig. 2. (A) Insertion of the femoral prosthesis in excessive anteversion risks postoperative anterior dislocation.
Furthermore, the eccentric loading of the acetabular component may result in early aseptic loosening because of
component toggle. (B) Insertion of the femoral prosthesis in normal anteversion avoids the problems encountered with
anterior instability. An efficient abductor lever arm may not be achieved, however, because the abnormal offset and
posteromedial position of the greater trochanter remains unchanged. Note the smaller canal diameter in the upper femur
when the femoral component is inserted in normal anteversion (a > b), necessitating at times the use of miniature or
custom-made prostheses.
various operations for underlying hip joint conditions.
Preoperatively, all the patients had anteroposterior and lateral radiographs of the hip as well as
m e a s u r e m e n t films of the lower limbs. To standardize the radiographs for the magnification factor, a
radiopaque ruler was placed adjacent to the pelvis
and the lower limbs w h e n taking the m e a s u r e m e n t
films. C o m p u t e d t o m o g r a p h y (CT) scans of the
pelvis and knees were used to m e a s u r e the angle of
anteversion. The m e a n anteversion angle was 68 °
(range, 50°-90°). The superior displacement of the
f e m u r was d e t e r m i n e d by m e a s u r i n g the vertical
distance b e t w e e n the teardrop and the s u p e r o m e dial corner of u p p e r femoral metaphysis on anteroposterior pelvic radiographs. The m e a n superior
displacement was 31 m m (range, 3-55 m m ) . Because it is our practice to restore the a n a t o m i c
position of the acetabular c o m p o n e n t , if the estim a t e d leg length increase was m o r e t h a n 20 to 30
m m , we shortened the f e m u r to avoid sciatic n e r v e
injury. In this series, 3 cases required femoral
shortening during THA, in 1 by 10 m m and in 2 by
30 m m . In 1 other case, angular correction was
p e r f o r m e d at the site of a previous subtrochanteric
osteotomy.
Using specialized c o m p u t e r software and the data
obtained f r o m the a f o r e m e n t i o n e d investigations,
an accurate 3 - d i m e n s i o n a l c o m p u t e r m o d e l of
the u p p e r femoral a n a t o m y was constructed. The
CAD/CAM custom prostheses were m a n u f a c t u r e d
at the Centre for Biomedical Engineering (Startm o r e Implants World Wide Ltd, Middlesex, United
Kingdom). The prostheses w e r e m a d e f r o m titan i u m alloy with c o b a l t - c h r o m e or ceramic interchangeable heads (22 or 28 m m diameter). The
prostheses used had the following design features
(Fig. 3): Proximally, there was a close i n t r a m e d u l lary fit, with collar, macrogrooves, lateral flare, and
h y d r o x y a p a t i t e coating, and distally the stem had
longitudinally cutting flutes with a polished finish at
its tip.
The rationale for employing these features was as
follows: The collar was aimed to rest on the calcar to
provide i m m e d i a t e resistance against subsidence
and to allow impaction at the o s t e o t o m y site during
implant insertion. Proximally, the prosthesis was
designed to fill the i n t r a m e d u l l a r y canal completely
and rest directly on the cortical surfaces. The lateral
flare was e m p l o y e d to increase further the torsional
and axial stability of the implant. The m a c r o g r o o v e s
w e r e 1.5 m m in depth, w e r e 3 m m in width, and ran
THAWith Subtrochanteric Derotation Osteotomy
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Zadeh et al.
685
cutting flutes provided i m m e d i a t e rotational stability across the o s t e o t o m y site, thus allowing easy
correction of the femoral length, rotational deformities, and angular deformities.
Surgical Technique
Fig. 3. A typical CAD/CAM (computer-assisted design/
computer-assisted manufacturer) custom prosthesis.
longitudinally along the intertrochanteric portion of
the implant and w e r e aimed to increase the surface
area for osseointegration. To p r o m o t e early osseointegration, m o s t of the implant surface was coated
with plasma-sprayed, highly crystalline h y d r o x y a p a tire, 75 B thick (Plasma Biotal Ltd, Tideswell, United
Kingdom). The implant stem was h e x a g o n a l in
cross-section with 6 1 . 5 - m m high longitudinally
cutting flutes. The outer stem diameter with the
cutting flutes was designed to be 1.5 m m larger t h a n
the femoral canal diameter. During surgery, the
femoral canal was r e a m e d to a d i a m e t e r 2 m m
smaller t h a n the outer stem diameter. We therefore
a i m e d for each cutting flute to e m b e d into the inner
cortical surface by 0.75 m m and into the m e d u l l a r y
cancellous b o n e by 0.25 m m . To ensure a stable
reduction, a m i n i m u m of 60 m m of stem length was
required b e y o n d the o s t e o t o m y level. The polished
tip m a i n t a i n e d the sharpness of the cutting flutes
and allowed easier insertion of the prosthesis.
The overall aim was to achieve p r o x i m a l i m p l a n t
fixation with an e v e n stress distribution a n d load
transfer at the b o n e - i m p l a n t interface [11]. The
Operative technique involves a p p r o a c h i n g the
hip joint t h r o u g h a standard posterior approach
(Fig. 4). This a p p r o a c h allows easy release of contracted tissues, such as piriformis, o b t u r a t o r internus, quadratus femoris, and posterior hip joint
capsule. After excising the femoral head, the acetabular cavity was p r e p a r e d using sequential reamers.
We prefer to use an u n c e m e n t e d p o r o u s - c o a t e d
c o m p o n e n t on the acetabular side, and we try to
insert this c o m p o n e n t as close to the true acetabul u m as possible. In 1 case, a c e m e n t e d p o l y e t h y l e n e
cup was used. Acetabular b o n e a u g m e n t a t i o n was
not required in a n y of our cases.
The distal femoral canal was p r e p a r e d using the T
handled and flexible r e a m e r s to a p r e d e t e r m i n e d
diameter of 2 m m smaller t h a n the outer diameter
of the implant stem. The proximal femoral canal
was t h e n p r e p a r e d using the c u s t o m - m a d e rasp,
which had the same dimensions as the prosthesis.
The rasp was introduced in accordance with the
existing femoral anteversion.
After r e m o v a l of the rasp, the subtrochanteric
o s t e o t o m y was m a d e just b e l o w the level of the
lesser t r o c h a n t e r by reflecting the vastus lateralis
anteriorly using a b o n e spike and dividing the b o n e
with an oscillating saw. We tried to m a i n t a i n
the muscle a t t a c h m e n t s p r o x i m a l and distal to the
o s t e o t o m y sites to avoid devascularization of the
bone. W h e n required, femoral shortening or angular correction was also p e r f o r m e d b e l o w this site by
resecting an appropriate s e g m e n t or wedge of bone.
The resected b o n e was used as a graft.
After the osteotomy, the b o n e ends w e r e held
with b o n e clamps, and the femoral prosthesis was
partially inserted. The rotational correction was
m a d e just before the final impaction of the prosthesis. The final position of the femoral prosthesis and
u p p e r f e m u r was 15 ° a n t e v e r t e d relative to the
knee. We h a v e not experienced a n y problems with
insertion of the prosthesis or closure of the osteo t o m y site. Further cancellous b o n e - g r a f t from
acetabular or femoral reaming was also applied
a r o u n d the o s t e o t o m y site before w o u n d closure.
Postoperatively, patients w e r e kept at partial weight
bearing for 6 weeks a n d progressed to full weight
bearing thereafter.
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The Journal of Arthroplasty Vol. 14 No. 6 September 1999
B
N
D
Results
Postoperatively, all patients were reviewed clinically and radiographically on a 6 - w e e k basis until
union at the o s t e o t o m y site and yearly thereafter.
The m e a n follow-up period was 31 m o n t h s (range,
1 6 - 6 0 m o n t h s ) . All patients considered their operation to h a v e b e e n w o r t h w h i l e and w o u l d undergo
the same procedure again u n d e r similar circumstances. Six of 7 patients experienced no pain, and ]
experienced mild discomfort on an occasional basis.
Five of 7 walked w i t h o u t a limp. The other 2
patients had a mild Trendelenburg gait, but both
patients had previously u n d e r g o n e failed pelvic and
femoral osteotomies for underlying joint dysplasia.
Only 1 of these patients required a walking aid for
mobilization outdoors, and the remaining 6 did not
use an aid at all. The average Harris hip score [12]
i m p r o v e d from 44 (range, 20-71) preoperatively to
91 (range, 78-97) on the latest follow-up (Fig. 5).
Radiographically, in all cases, the prosthesis appears
to have osseointegrated with no macroscopic evidence of implant migration or significant translucent lines at the b o n e - i m p l a n t interface. The osteo t o m y site united soundly in 6 cases within 3
m o n t h s and fully consolidated by 1 year. In 1 case,
Fig. 4. (A) The operative technique involves approaching
the hip joint through a standard posterior approach. The
femoral head is then cut and
excised. (B) The femoral canal
is prepared using the Thandled
and flexible reamers. (C) The
custom-made rasp is used to
ream the proximal femoral canal accurately. The original
femoral anteversion is initially
maintained. (D) The rasp is
withdrawn, and the osteotomy
is made just below the level of
the lesser trochanter. If required, femoral shortening or
angular correction is also performed at this stage, below the
osteotomy site. (E and F) The
bone ends are held with bone
clamps, and the rotational correction is made just before the
final impaction of the prosthesis.
the progress was initially complicated by persistent
pain and suspected delayed union. At 3 m o n t h s
after the arthroplasty, a second p r o c e d u r e was
p e r f o r m e d for application of b o n e - g r a f t and t e m p o rary stabilization with a plate using the Dall-Miles
system (Howmedica Ltd, London, United Kingdom). Two screws and 1 cable w e r e e m p l o y e d on
either side of the osteotomy, and it united u n e v e n t fully within 3 months. The plate was r e m o v e d 9
m o n t h s later after consolidation of the osteotomy.
In retrospect, the femoral stem length b e y o n d the
o s t e o t o m y was inadequate in this case (50 m m ) ,
and with a longer stem prosthesis, this complication
m a y h a v e b e e n avoided.
Discussion
Although the transtrochanteric a p p r o a c h is the
m o s t widely reported technique in THA in patients
with CDH or subluxation, we do not favor this
technique because of the inherent problems associated with trochanteric o s t e o t o m y and excision of
calcar, as discussed earlier. In this series, uncem e n t e d CAD/CAM custom prostheses w e r e used in
conjunction with the subtrochanteric derotational
or shortening osteotomy. Off-the-shelf u n c e m e n t e d
THAWith Subtrochanteric Derotation Osteotomy
•
Zadeh et al.
687
fJ'~.
i
¸
B
Fig. 5. (A) Preoperative radiograph of a 45-year-old patient with osteoarthritis of the right hip joint secondary to
congenital dislocation of the hip treated nonoperatively in childhood. (B) Preoperative computed tomography scan. (C)
Immediate postoperative radiographs. Femoral shortening was required in this case, and the resected bone was used as
bone-graft. After derotation, the normal morphology and offset of the greater trochanter on anteroposterior view has
been restored. (D) Radiographs taken 18 months after surgery show sound union at the osteotomy site and
osseointegration of the implant.
systems that offer distal rotatory control m a y also be
used in preference to a c u s t o m - m a d e prosthesis to
provide adequate stability across the o s t e o t o m y site.
Femoral shaft fracture is a well-recognized complication during insertion of a prosthesis into an underr e a m e d femoral shaft. This p r o b l e m m a y easily be
avoided, however, by using a fluted stem design
with sufficiently sharp and flexible edges. In this
series, we did not experience any problems with
insertion of the prosthesis into the distal fragment.
The flutes provided a d e q u a t e purchase distally to
resist against torsional stresses.
THA with subtrochanteric derotational o s t e o t o m y
in severe femoral anteversion is not a n e w concept.
Holtgrewe and Hungerford [7] reported their experience with this technique in 2 patients using
standard u n c e m e n t e d implants. One of the problems they faced was rotational instability at the
o s t e o t o m y site, which required t e m p o r a r y fixation
with a plate. The plates w e r e r e m o v e d at a second
operation. Sponseller and McBeath [13] in a case
report described a similar technique, but because
they used a c u s t o m - m a d e u n c e m e n t e d prosthesis
with a long curved stem, a d e q u a t e stability was
achieved at the o s t e o t o m y site, and additional fixation was not necessary. Two further cases were
reported by Morscher [14] in a review article. In 1
case, the operative technique was similar to the
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The Journal of Arthroplasty Vol. 14 No. 6 September 1999
cases d e s c r i b e d b y H o l t g r e w e a n d H u n g e r f o r d . I n
t h e other, a W a g n e r C o n e P r o s t h e s i s (Protek, B e r n e ,
S w i t z e r l a n d ) w a s u s e d . B e c a u s e of t h e f l u t e d s t e m
d e s i g n of t h e W a g n e r C o n e Prosthesis, sufficient
s t a b i l i t y w a s a c h i e v e d across t h e o s t e o t o m y site, a n d
a d d i t i o n a l f i x a t i o n w a s n o t r e q u i r e d . I n o u r series of
p a t i e n t s , w e also f o u n d t h e f l u t e d s t e m d e s i g n to b e
a r e l i a b l e m e a n s of a c h i e v i n g r o t a t i o n a l s t a b i l i t y
across t h e o s t e o t o m y site, a n a d v a n t a g e of a n
uncemented implant.
Conclusion
We find CAD/CAM custom total hip replacement
with subtrochanteric derotational osteotomy a useful a n d r e l i a b l e t e c h n i q u e in THA w i t h c o n c o m i t a n t
s e v e r e f e m o r a l a n t e v e r s i o n . The e a r l y r e s u l t s of this
t e c h n i q u e 1o d a t e h a v e b e e n e n c o u r a g i n g a n d a r e
c o m p a r a b l e w i t h o t h e r p u b l i s h e d series [ 1 - 7 , 9 ] .
Acknowledgment
W e t h a n k E v e l y n H u n t e r for h e r v a l u a b l e assistance.
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