Artificial Lumbar Disc Replacement

Transcription

Horizon Scanning Report
Artificial Lumbar Disc Replacement
(update)
January 2006
<TITLE OF REPORT> - <MONTH YEAR>
© Commonwealth of Australia [2006]
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This Horizon scanning report was prepared by staff from the Australian Safety and
Efficacy Register of New Interventional Procedures – Surgical (ASERNIP-S).
2
Table of Contents
Background ......................................................................................1
Background to the Condition ...................................................................... 1
Description of the Technology ................................................................... 1
Treatment Alternatives.....................................................................5
Existing Comparators ................................................................................... 5
Clinical Outcomes............................................................................6
Effectiveness .................................................................................................. 6
Safety.............................................................................................................. 12
Potential Cost Impact .................................................................... 18
Cost Analysis ................................................................................................ 18
Ethical Considerations ................................................................... 18
Informed Consent ....................................................................................... 18
Access Issues ................................................................................................ 18
Training and Accreditation ............................................................ 18
Training ......................................................................................................... 18
Clinical Guidelines....................................................................................... 19
Limitations of the Assessment ....................................................... 19
Search Strategy Used for Report ............................................................... 19
Availability and Level of Evidence ........................................................... 20
Sources of Further Information...................................................... 21
Impact Summary............................................................................22
Conclusions ....................................................................................22
References ......................................................................................24
Appendix A: Table of Key Efficacy and Safety Findings..............29
Artificial lumbar disc replacement
Background
Background to the Condition
Lower back pain can result from many factors, including: structural disease, neoplasms,
referred pain to the spine, infection, inflammatory disease, and metabolic disorders
(Speed 2004). Most types of lower back pain are associated with degeneration of the
intervertebral disc (Fairbank 2002).
Numerous therapies are available to treat lower back pain, including analgesic and antiinflammatory medication, behavioural and exercise therapies, surgery and spinal cord
stimulation (Boden et al. 2004; Bogduk 2004). Surgical management has been mostly
reserved for patients in whom other treatment options have failed. The main surgical
treatment is fusion of the affected vertebral disc space, which was also used in other
joints (eg. knee, hip) until reliable arthroplasty techniques were developed (Szpalski et al.
2002). Lumbar arthroplasty, or replacement of the disc with an artificial intervertebral
disc, has potential advantages. These include maintenance of a more physiological range
of movement and load distribution in the lumbar spine (Boden et al. 2004). The number
of patients receiving artificial lumbar disc replacements has dramatically increased in
recent years, with an ASERNIP-S report and a systematic review of the literature
published in 2003 (de Kleuver et al. 2003). However, a number of studies have been
published in the intervening period and this report is an update including more recently
published results.
Description of the Technology
The intervertebral disc is not a simple joint, but a mixed structure consisting of a
peripheral collagenous band (annulus fibrosus), uniting the adjacent vertebral endplates,
and a central core (nucleus pulposus). (Szpalski et al. 2002)
The artificial disc needs to: restore disc height and decompress neural structures; realign
vertebral bodies; and by precise positioning of the device, restore the relationship
between sagittal balance, movement and the guiding function of the facet joints. In
addition, artificial discs need to have a long lifespan as a patient may live for many years
after implantation of the disc. While experimental techniques for disc replacement have
been used since the 1950s (Blumenthal et al. 2002), major development of artificial
lumbar discs only began in the 1980s (Boden et al. 2004).
1
This report is restricted to the artificial lumbar intervertebral discs which have been used
clinically. These include:
LINK SB Charité
The artificial lumbar disc with the longest record of use and greatest number of cases
worldwide is the Charité III prosthesis. In September 1984, the Charité I artificial disc
was implanted for the first time in a patient at the Charité Hospital in Berlin (Link 2002).
The Mark –I and –II implants were manufactured in the former German Democratic
Republic only, had problems with migration and metal fatigue fractures, and were never
commercially available. LINK (Waldemar Link GmbH and Co, Hamburg, Germany)
started production of the LINK SB Charité III disc in 1987, with the company acquired
by DePuySpine in June, 2003. The Charité III (DePuySpine, Inc. Raynham,
Massachusetts, USA) artificial disc has been widely used in Europe and the United
Kingdom. The US FDA accepted the premarket approval application for the Charité III
artificial disc on June 3, 2004, with conditions including: following the patients enrolled
in the investigational device exemption (IDE) study for at least two years; providing
patients with documentation describing the implant; a post market in vitro study to assess
wear debris; and a consideration of required surgeon training (FDA 2004).
The Charité III disc consists of a biconvex ultra-high-molecular-weight polyethylene
nucleus with a radio-opaque metallic ring. This interfaces with two endplates of cobaltchromium-molybdenum alloy, coated with titanium and hydroxyapatite and primarily
fixed by ventral and dorsal teeth. The plates are currently available in five footprint
configurations adaptable to the size of the vertebral endplates, each with four available
angles (0,5, 7.5 and 10o), allowing for built-in lordosis with variations of 0o to 20o (Geisler
et al. 2004).
Charité III artificial disc (used with permission of DePuySpine Inc., USA)
2
ProDisc II
The ProDisc was developed by Dr Thierry Marnay, a French spine surgeon, in the late
1980s. It was developed by Spine Solutions Inc., later acquired by Synthes-Stratec in
February, 2003. ProDisc II (Synthes-Stratec, Oberdorf, Switzerland) was launched in the
European market in December 1999, and since that time more than 2000 ProDisc
devices have been implanted in Europe (Boden et al. 2004). A multicentre FDA IDE
study began in the US in October 2001. In February, 2003, the ProDisc® was being sold
in 26 countries in Europe, Asia Pacific, Latin America and South Africa (Synthes-Stratec
2003).
The ProDisc consists of two metal alloy endplates with midline keels. These are impacted
into the surgically evacuated disc space, then an ultra-high molecular weight polyethylene
domed component is snap-fitted into the inferior endplate. Assembly is performed inside
the disc space with the space internally distracted (separated). There are two endplate
sizes (medium and large), three heights of the polyethylene component (10, 12 and 14
mm) and two lordosis angles (6o and 11o). Minimal access approaches are possible and
the ProDisc II is the only artificial disc being investigated for multiple level lumbar disc
disease (spine-health.com 2004).
Maverick
The Maverick (Medtronic Sofamor Danek) artificial disc is a two piece metal-on-metal
design, using a smaller and more posteriorly placed rotational centre. (Boden et al. 2004)
Two large keels are used for rotational control, similar to the ProDisc II. The cobaltchromium-alloy components are coated with hydroxyapatite. A four-in-one guide
instrument maintains intraoperative lordosis, measures depth and height distraction and
guides chiselling during insertion. More than 120 Maverick discs have been implanted in
Europe (Boden et al. 2004), where clinical series are now being studied. A nationwide US
clinical trial was started in April 2003, to assess the safety and efficacy of the disc.
FlexiCore
The FlexiCore artificial disc was developed by SpineCore, which was acquired by Stryker
in July 2004. The FlexiCore disc (Stryker Corp. Kalamazoo, MI, USA) is a metal-onmetal device which is inserted as a single unit. The superior and inferior parts are linked
by a ball-and-socket joint, and can be implanted from a straight anterior or anterolateral
direction. This offers the ability to manipulate the position of the implant within the
intervertebral space. Domed baseplate surfaces are shaped to approximate the
concavities of the vertebral body endplates, and coated with titanium plasma spray to
assist bone ingrowth. A US FDA IDE study is currently underway for patients with
single-level disc disease.
3
Acromed Acroflex
Clinical results using Acroflex Acromed (DePuy Acromed, Raynham MA, USA) artificial
discs were published in 1993 (Enker et al. 1993). This publication states that the disc was
being re-designed so that only a single piece of rubber was used as the inner core
component. AcroFlex discs made from titanium/polyolefin have been implanted into
patients in Adelaide, Australia (Freeman et al. 2001). However, clinical development of
this disc has been terminated. Since there are patients in whom this disc has been
implanted, the clinical studies are included in this report.
The Procedure
The precise method of implantation of the artificial lumbar disc can vary. Generally, an
anterior retroperitoneal approach is used, via a small incision below the umbilicus. Once
the disc is visualised, it is either partially or fully excised (depending on the prosthesis
used). In most cases the vertebral endplates and surrounding spinal ligaments are
preserved. Minimally invasive approaches for implantation of the Charité III and
ProDisc II have also been used (Buttner-Janz 2002; Mayer et al. 2002).
Intended Purpose
The purpose of the artificial lumbar intervertebral disc is for replacement of the disc
where surgically indicated, i.e. in patients with diseases involving the lumbar intervertebral
disc.
Clinical Need and Burden of Disease
•
•
It has been recently estimated approximately 79% of Australian adults suffer from
lower back pain at some time during their life (Walker et al. 2004).
Patients who may benefit from artificial lumbar disc replacement are those with
severe back pain, where other treatments have not been successful. These patients
may not have any other treatment options.
Stage of Development
•
•
The FDA in the US have recently approved the use of the Charité III artificial disc,
with a requirement for DePuy Spine to conduct a post-approval study to assess the
product’s long-term safety and effectiveness, including its impact on other discs and
on the bony structures on the back of the spine (FDA 2004). The FDA is expected
to have approved the ProDisc II artificial disc by 2005, and several other companies
are also developing artificial lumbar discs for clinical use.
The Charité artificial lumbar disc has had TGA approval in Australia since 1995
(ARTG Number 96121; Product ID 115765). As of September 2004, over 600
4
•
•
•
Charité artificial lumbar discs have been implanted in Australia (personal
communication).
The ProDisc II artificial lumbar disc is being marketed in Australia by Taylor Bryant
(Taylor Bryant 2004).
As of March 2004, the Medicare Benefits Branch has agreed to fund disc
replacement surgery as an interim measure until the FDA research findings are
released, when ongoing funding will be reviewed. The MBS item numbers 48660 or
48669 in association with 48684 for spinal disc replacement have been
recommended for use.
The Medical Services Advisory Committee (MSAC) recently commenced an analysis
of spinal disc replacement, with the findings expected to be released in 2005.
Treatment Alternatives
Existing Comparators
There are many non-surgical alternatives for lumbar intervertebral disc disease (eg.
physiotherapy, analgesia, anti-inflammatory medication), however, some patients remain
in considerable pain with surgery the only remaining option. The main surgical treatment
used has been spinal fusion, with proposed advantages of prosthetic disc replacement
compared with spinal fusion being:
•
•
•
•
•
Maintenance of range of motion for the affected spinal unit. Proper kinematics and
load sharing properties of the functional spinal unit could be maintained.
Mobility of adjacent discs may be preserved, which could delay the onset of
accelerated degenerative changes in adjacent levels, a common occurrence following
spinal fusion.
Sources of autoimmune and or inflammation-provoking substances emanating from
the degenerated disc may be removed if the disc itself is excised and replaced.
There is a lack of predictable pain relief following spinal fusion.
Unsatisfactory results from spinal fusion, such as pseudoarthrosis and bone graft
donor site complications, could be avoided (Boden et al. 2004).
The other relatively new surgical option for patients with lumbar intervertebral disc
disease is disc nucleus replacement, which may allow less invasive surgery to be
performed versus replacement of the entire disc (Bertagnoli and Schonmayr, 2002). This
procedure is beyond the scope of the present report.
5
Clinical Outcomes
There were 28 studies in total identified: one systematic review; 17 studies using the
Charité III (two RCTs, one non-randomised comparative study and 14 case series); 7
studies using the ProDisc II (two single centre reports from the multicentre RCT and
five case series); one case series using the Maverick disc; and two studies used two
different Acroflex artificial discs.
Effectiveness
Clinical outcome
The definition of clinical success varied between the studies; in some studies the criteria
used to define success were not stated at all. Results are given according to the clinical
success reported in each study, but it should be noted these numbers may not be directly
comparable. Details of the individual study profiles are given in Appendix A.
Charité III
The RCT conducted by Blumenthal et al. (2005) comparing the Charité III artificial disc
versus spinal fusion surgery with the BAK titanium cage (control) reported that patients
of the Charité III group achieved a statistically greater improvement (p<0.05) in ODI
and VAS scores compared to the control group at all time points except for the 24
month follow-up. Overall clinical success (defined by ≥25% improvement in ODI scores
at 24 months compared to preoperative scores, no device failure, no major complications
and no neurological deterioration compared to preoperative status) was achieved in
57.1% of patients in the Charité III group and 46.5% of the control group (p<0.0001). In
the subset patients who completed the 24 months follow-up, overall clinical success was
significantly greater in the Charité III group (63.6%) compared to the control group
(56.8%) (p=0.0004). Neurological complications from this study was described
previously by Geisler et al. (2004), where no significant differences in neurological status
were reported between the groups (79% (141/179) of Charité III versus 82% (65/79) of
BAK patients had no change in neurological status at 24 months) (Geisler et al. 2004).
In a case series, Muschik & Meergans compared patients having Charité replacement
discs because of degenerative disc disease (DDD) or postnucleotomy syndrome (PNS)
(Muschik and Meergans 2003). There were 79% (23/29) of DDD patients with a
complete or satisfying improvement versus 40% (4/10) in the PNS group.
6
In 12 of the 17 case series with clinical outcome reported, Charité disc replacement
resulted in 0% to 100% of patients achieving clinical success, with a median value of 75%
(see Table 1). In four studies the clinical success was not stated. The lowest rate of
success was in a study in which patients with complications were admitted to a specialist
centre, therefore the group were a biased sample (van Ooij et al. 2003). Unsatisfactory
results were found in 0% to 100% of patients, with a median value of 11%.
Table 1: Clinical outcomes after Charité disc replacement in the included case series
Study
Caspi et al. 2003
David 2003
Kim et al. 2003
Muschik & Meergans
2003
Pimenta et al. 2003
Su et al. 2003
van Ooij et al. 2003
Buttner-Janz et al. 2002
Hopf et al. 2002
Scott-Young & Tan 2002
Sott et al. 2000
Zeegers et al. 1999
LeMaire 1997
Mean follow-up
Patient no
Clinical Success*
1-11 months
26 months
53 months
n=20
n=21
n=5
DDD: n=29
PNS: n=10
n=55
n=31
n=26
6 months-13 years
14.7 months
20 months
48 months
minimum 2 years
51 months
n=20
n=35
n=86
n=14
n=46
n=105
68%
100%
100%
DDD: 79%
PNS: 40%
not stated
94%
46% mean 53 months
(range 1 month-10 yrs)
0% mean 91 months
(range 15-157 months)
95%
not stated
84%
71%
70%
79%
48 months
4 years
>6 months
2 years
Unsatisfactory
outcome
20%
0%
0%
DDD: 21%
PNS: 40%
not stated
0%
100%
mean 91 months
(range 15-157 months)
5%
not stated
14%
30%
15%
Ross et al. 1997
3 years
not stated
not stated
Cinotti et al. 1996
3.2 years
n=46
63%
7%
Griffith et al. 1994
11.9 months
n=93
not stated
not stated
David et al. 1993
minimum 1 year
n=22
65%
not stated
*: clinical success as defined by the authors; DDD: degenerative disc disease: PNS: post-nucleotomy
syndrome
ProDisc II
Two separate centres have published initial results from the FDA IDE multicentre RCT
comparing ProDisc II implantation versus spinal fusion. In both studies the VAS and
Oswestry scores significantly decreased in both groups, with a more rapid reduction in
the ProDisc II patients. The ODI score was significantly reduced by 3 months in the
ProDisc II versus 6 months in the fusion group, but at 24 months the ODI scores were
25.8 in the Charité group versus 30.1 in the BAK group (p=0.54) (Delamarter et al. 2003).
There were five case series using the ProDisc II artificial disc. Clinical success ranged
from 0% to 100%. The 0% success was in a report of only two patients, both having
complications (Aunoble et al. 2004). Without this study, success rates were 83% to 100%.
In one study the surgery was performed using a minimally invasive technique (Mayer et al.
2002).
7
Table 2: ProDisc II Clinical Results
Study
Bertagnoli et al. 2005
Aunoble et al. 2004
Tropiano et al. 2003
Bertagnoli & Kumar 2002
Mayer et al. 2002
Mean follow-up
31 months
(median)
4-20 months
1.4 years
3 months to 2
years
5.8 months
Patient
no
104
Clinical
Success
96%
Unsatisfactory
outcome
4%
2
53
108
0%
100%
98%
100%
0%
0%
34
83%
17%
Other implants
In Enker et al. (1993) six patients received Acroflex Acromed discs (AcroMed
Corporation, Cleveland, USA), with good to excellent results in three patients, fair results
in one patient, and a poor result in two patients.
Freeman et al. (2001) used an AcroFlex disc in eleven patients, with an average
improvement of 39% in VAS and 12 points in ODI score at a minimum of 12 months
follow-up.
One paper in abstract form only was available describing clinical use of the Maverick disc
prosthesis. Discs were implanted in 30 patients, with an 86% improvement in Oswestry
score at one year, and a reduction in VAS (LeHuec et al. 2003).
Hospital stay and operative times
Charité III
Hospital stay and operative times were reported in subgroups of the RCT comparing
Charité III versus BAK surgery. In Blumenthal et al. (2003) the operative times in the
first 57 Charité III patients were a mean of 95.2 minutes at L4-L5 (n=12) and a mean of
74.4 minutes at L5/S1 (n=45, p<0.05). In McAfee et al. (2003) times were only given for
the combined groups and not for the separate procedures. Surgery length for the
combined groups was a mean of 88.4 minutes (range 57-137 minutes) and hospital stay a
mean of 3.03 days (range 2-6 days) (n=41 Charité III and n=19 BAK, total n=60)
(McAfee et al. 2003a).
In the 2005 update, Blumenthal et al. (2005) reported a mean operative time of 110.8
minutes for Charité III patients (n=205) with mean hospital stay of 3.7 days.
Operating times were stated in two case series: a mean of 180 minutes (Kim et al. 2003)
and 86 minutes (Hopf et al. 2002). Length of hospital stay was given in only one study,
with a mean of 16.8 days (Hopf et al. 2002).
8
ProDisc II
In a subgroup of the RCT, hospital stay and operative times were reported to be shorter
in the ProDisc II versus fusion patients (Zigler 2003).
In the ProDisc II case series, mean operative times were 104 (Tropiano et al. 2003) to 131
minutes (Mayer et al. 2002); mean hospital stay was 9 days (Tropiano et al. 2003) to 12
days (Mayer et al. 2002).
Acroflex
In the study using the more recent Acroflex disc, mean operating time was 135 minutes
and hospital stay 6.3 days (Freeman et al. 2001).
Range of Motion
Range of Motion measures the degree to which a patient can perform movement of
flexion, extension, lateral bending, and spinal rotation. The range of motion was most
commonly measured using flexion-extension radiographs.
Charité III
Patients with the Charité disc had greater flexion-extension range of motion at 24
months versus the BAK patients (mean 7.4o [5.28o] (n=179) versus 1.1o [0.87 o] (n=79)
(assumption made that all patients at 24 months had flexion-extension measurements
performed). (Geisler et al. 2004)
Patients with the Charité disc had greater flexion-extension range of motion at 24
months versus the BAK patients (mean 7.4o [5.28o] (n=179) versus 1.1o [0.87 o] (n=79)
(assumption made that all patients at 24 months had flexion-extension measurements
performed).
McAfee et al. (2005), reported that Charité III patients attained a 113.6% improvement in
range of motion at 24 months (measured by lateral flexion/extension films) compared to
preoperative measurements (13.6% increase).
Six case series reported vertebral mobility following Charité III implantation. Average
mobility values of 9o or 12o (Cinotti et al. 1996; David 2003; Su et al. 2003) or a range of
3o to 9o (Caspi et al. 2003) were found. In Buttner-Janz et al. (2002) the mean value for
unisegmental implantation was 6.8o and for bisegmental implantation 5.8o (Buttner-Janz
et al. 2002). LeMaire (1997) reported the range of motion at L4/L5 was 12o and 9.5o at
L5/S1. Mobility in patients following Charité III implantation for degenerative disc
disease was 8o , and 6o for patients with postnucleotomy syndrome (Muschik and
Meergans 2003).
9
ProDisc II
In the study reporting initial results from the RCT, at six to 15 months follow-up
Delamarter et al. (2003) found greater motion at the L4/L5 segment in ProDisc II (n=35)
versus fusion patients (n=18, p<0.05). A similar trend was seen at L5/S1, but this did
not reach statistical significance. In another subgroup, Zigler et al. (2003) stated that at six
months ProDisc II patients (n=28) had significant improvement in range of motion
compared to preoperative values, and better motion than the fusion patients (n=11).
Two case series reported range of motion after ProDisc II implantation. In Tropiano et
al. (2003) values were 8o at L5/S1 (range 2-12o) and 10o at L4/L5 (range 8-18o) (n=53).
The other study reported average range of motion at four levels: 12o (range 9-15o) at
L2/L3; 10o (range 8-15o) at L3/L4; 10o (range 9-13o) at L4/L5; and 9o (range 2-13o) at
L5/S1 (n=108) (Bertagnoli and Kumar 2002).
10
Other implants
Enker et al. (1993) stated patients with Acroflex Acromed implants had an average lateral
flexion/extension of 8o (range 2-16o).
No values were given by Freeman et al. (2001), although it was stated that ten of eleven
patients had satisfactory movement of the vertebral motion segment, as shown by cinefluoroscopy (Freeman et al. 2001).
In the one study using the Maverick implant, the range of motion was a mean of 6o [4o]
(range 3-12o) (LeHuec et al. 2003).
Secondary Surgery
Charité III
In a subgroup of the RCT, McAfee et al. (2003) reported no patients required additional
spinal reconstructive surgery in either the Charité III (n=41) or BAK (n=19) groups at
one to three years follow-up.
Blumenthal et al. (2005) reported that device failures necessitating reoperation, revision
or removal was detected in 11 Charité patients (5.4%). In addition to this, approach
related complications were noted in 20 (9.8%) Charité patients.
In the Charité III case series, secondary surgery was reported in nine studies (see Table
4). The incidence of secondary surgery was between 0% and 56%. Reasons for further
surgery included disc migration (Caspi et al. 2003), endplate fracture (LeMaire et al. 1997)
and insertion of a smaller prosthesis (Cinotti et al. 1996). In a group of referred patients
with complications, 56% had secondary surgery, with four patients having removal of the
prosthesis and secondary salvage procedures in another 11 patients (van Ooij et al. 2003).
Table 4: Secondary surgery in case series following Charité III implantation
Study
Caspi et al. 2003
Re-operation
10% (2/20)
Kim et al. 2003
Muschik & Meergans
2003
Van Ooij et al. 2003
0% (0/5)
5% (2/39)
56% (15/27)
Zeegers et al. 1999
24% (12/50)
LeMaire 1997
1% (1/105)
Ross et al. 1997
Cinotti et al. 1996
4.3% (2/46)
2% (1/46)
3% (3/93)
Reason
Disc migration related to incomplete severing of
post-longitudinal ligament (n=1) and fracture of
the lower endplate (n=1).
Posterior subluxation of the implant (n=1) and
fusion after 4 months (n=1).
Removal of prosthesis (n=4) and second spinal
reconstructive salvage procedure (n=11)
At segment with prosthesis (n=6); at another
level (n=1) or because of complications (n=3).
Revised to fusion because of an endplate
fracture.
not stated
Revised to a smaller prosthesis.
Revised to percutaneous nucleotomy,
foraminoplasty and A-P spinal fusion
11
ProDisc II
Delamarter et al. (2003) reported no patients required revision surgery after either
ProDisc II or spinal fusion surgery.
Two case series reported secondary surgery following ProDisc II implantation. In
Aunoble et al. (2003) both patients had spinal fusion surgery because of dislocation of the
polyethylene core of the artificial disc (Aunoble et al. 2004). Tropiano et al. (2003) found
6% (3/53) of patients required secondary surgery, one for a vertebral body fracture and
two patients for malposition of the disc prosthesis (Tropiano et al. 2003).
Other implants
In Enker et al. (1993) there was one patient (1/6) requiring re-operation as a result of a
fracture through the rubber core of the Acroflex Acromed artificial disc.
Freeman et al. (2001) did not state whether or not secondary surgery was necessary in any
patients.
Le Huec et al. (2003) reported no patients required removal or revision of the Maverick
artificial disc out of thirty patients followed up to one year postoperatively.
Safety
Many of the complications following artificial lumbar disc replacement are the same as
after any form of lumbar surgery, for example damage to the blood vessels or nerves in
the area of surgery. However, there were also device specific complications, such as disc
migration or dislocation, and device failure.
Charité III
In the RCT, no difference was seen in neurological adverse events in patients having
Charité III versus BAK surgery (16.6%, 34/205 of Charité III versus 17.2%, 17/99 of
BAK patients) (Geisler et al. 2004). Of these, 1.5% (3/205) of events in the Charité III
patients were related to the device, with one (a nerve root injury) classified as severe. A
centre participating in this RCT also presented results from their cohort, reporting one
death unrelated to the spinal procedure, and one patient with postoperative small bowel
obstruction of uncertain origin (McAfee et al. 2003a). It was stated adhesions of the
greater omentum were found at surgery, and that the use of the self-retaining Thompson
retractor to retract the bowel is now ‘curtailed’. It was not stated which groups these
patients were from. In the total cohort there was one case each of: retrograde ejaculation,
depression, adynamic ileus requiring a nasogastric tube, adynamic ileus not requiring a
nasogastric tube, urinary tract infection, epididymitis, lateral epicondylitis and
degenerative changes at the vertebral level above (McAfee et al. 2003b).
12
The 2005 update by Blumenthal et al. (2005) on this RCT reported no serious device
failures that resulted in death or injury. However, device failures that resulted in
reoperation, revision or removal occurred in 11 Charité III patients (5.4%). Collapse or
subsidence of the Charité III disc into adjacent vertebrae occurred in 7 (3.4%) patients
and there was one case (0.5%) of implant displacement (Blumenthal et al. 2005).
13
Table 3: Charité III complications in case series
Study
Patient
no
20
Total complications
Device related complications
5 (25%)
David 2003
Kim et al. 2003
Muschik & Meergans
2003
21
5
39
2 (10%)
0%
4 (10%)
Pimenta et al. 2003
55
11 (20%)
Su et al. 2003
31
not stated
27
(early)
26
(late)
9 (33%) early
26 (100%) late
Buttner-Janz et al. 2002
Hopf et al. 2002
Scott-Young & Tan 2002
Sott et al. 2000
20
35
86
14
Zeegers et al. 1999
46
9 (45%)
not stated
not stated
1 (7%)
minor complication
8 (15%) permanent
LeMaire 1997
105
11 (10%)
Cinotti et al. 1996
46
21 (46%)
93
53 (57%) total
30 (32%) not device
related
16 (17%) equivocal
2 (10%)
disc migrations (n=2) and device
failure (n=1)
not stated
0%
1 (3%)
posterior subluxation of the
implant (n=1)
2 (4%)
implant subsidence (n=2)
1 (3%)
displacement of core without
clinical symptoms (n=1)
2 (7%) early
1 (3.5%) asymmetrical insertion
1 (3.5%) dislocation of disc
26 (100%) late
18 (67%) subsidence
2 (7%) disc migration
10 (38%) prosthesis too small
1 (3.5%) disc dislocation
2 (7%) device breakage
1 (3.5%) subluxation
3 (12%) overdistraction of
segment
not stated
not stated
not stated
1 (7%)
implant migration
2 (4%)
poor implantation
3 (3%)
46 (44%) varying disc migration
(not clinically significant)
1 (2%) disc migration
4 (9%) undersized prosthesis
9 (20%) subsidence on
radiograph
1 (1%) implant failure
5 (4%) implant migration
1 (1%) implant dislocation
Caspi et al. 2003
van Ooij et al. 2003
Complications were reported in 13/15 of the other Charité III case series (see Table 3).
Total complications rates ranged from 0% to 100%. The zero complication rate was
from a study including only five patients, while van Ooij et al. (2003) reported a selected
group of 26 patients, all presenting at a specialist clinic with complications. Disregarding
these two studies, complication rates were between 10% (David 2003; LeMaire et al.
1997; Muschik and Meergans 2003) and 52% (Griffith et al. 1994) in the remaining
studies.
14
Device-related complications were between 0% (Kim et al. 2003) and 100% (van Ooij et
al. 2003) in the Charité III case series. The most common complication in van Ooij et al.
(2003) was subsidence of the disc, occurring in 67% of patients. Other complications
included asymmetrical insertion, disc migration, the prosthesis being too small and device
breakage. Without these two studies, device-related complications occurred in 3% (Su et
al. 2003) to 10% (Caspi et al. 2003) of patients. Complications in these studies included:
implant migration or dislocation, implant subsidence, poor implantation, and incorrect
size of prosthesis used. Implant failures were reported in three studies (Caspi et al. 2003;
Griffith et al. 1994; van Ooij et al. 2003). Caspi et al. (2003) stated migration of the disc
was because of incomplete severing of the post-longitudinal ligament in one patient and
following a small fracture of the lower endplate in another patient; in both cases a larger
prosthesis was inserted.
ProDisc II
Two studies presented initial results from their centres, involved in the multicentre RCT
comparing ProDisc II implantation versus spinal fusion. Neither study reported total
complications rates in the patients. In Delamarter et al. (2003) there were no incidents of
implant migration, breakage, or mechanical failure after disc replacement.
Bertagnoli et al. (2005) reported no incidents of device related complications while the
other four case series reported complications following ProDisc II implantation. Total
complication rates were between 1% and 9%. (Bertagnoli and Kumar. 2002; Mayer et al.
2002; Tropiano et al. 2003). Device-related complications were between 0% (Bertagnoli
and Kumar 2002) and 100% (Aunoble et al. 2004). In the latter study only two patients
were included, both of whom had dislocation of the disc.
Table 4: ProDisc II Complications
Study
Aunoble et al. 2004
Tropiano et al. 2003
Bertagnoli & Kumar 2002
Mayer et al. 2002
Patient no
Total complications
2
100%
53
108
34
5 (9%)
1 (1%)
3 (9%)
Device related
complications
100%
dislocation of disc
3 (6%)
0%
0%
Other implants:
In Enker et al. (1993) there was one patient (1/6) with an implant failure, a fracture
through the rubber core of the Acroflex Acromed artificial disc. However, there were no
cases of local or systemic complications.
Freeman et al. (2001) stated there was an early partial displacement of the AcroFlex
artificial disc in 1/11 patients, but no operative complications occurred.
In thirty patients with a Maverick disc prosthesis, there was one complication (3%)
unrelated to the disc implant, an injury to the ureter (LeHuec et al. 2003). At one year
postoperatively there was no evidence of either disc subsidence or migration.
15
Bleeding and related complications
Charité III
In the RCT comparing Charité III versus BAK surgery approximately two thirds of cases
during disc space distraction for Charité III implantation showed some epidural bleeding
or significant bone bleeding along the posterior edge. This was managed by placing strips
of Avitene in the disc space and compressing them. In the first 57 consecutive Charité
patients as part of this RCT, Blumenthal et al. (2003) stated mean blood loss was 266 ml
from L4/L5 (n=12) and 101 ml from L5/S1 (n=45), with a significant difference in
blood loss between the two levels (p<0.05) (Blumenthal et al. 2003). In the 2005 report
on this RCT, Blumenthal et al. (2005) reported a mean blood loss of 205ml in Charité III
patients.
In David (2003) there was one case (1/21, 5%) of epidural vein bleeding. LeMaire et al.
(1997) stated that 5% (5/105) of patients had vascular complications, although further
details were not given. Mean blood losses reported were 125 ml (Hopf et al. 2002) and
300 ml (Kim et al. 2003). Griffith et al. (1994) reported vein injury occurred in 17%
(16/93) of patients. An aortic lesion (1/50, 2%) was reported in Zeegers et al. (1999),
related to removal of the prosthesis. Haematomas occurred in 12 patients in this study,
with a retroperitoneal haematoma in one patient (Zeegers et al. 1999).
ProDisc II
Blood loss was not reported in the RCT comparing ProDisc II implants with spinal
fusion surgery (Delamarter et al. 2003; Zigler 2003) and was given in only one case series
using this device with a minimally invasive approach: mean blood loss was 117 ml per
level, with a range of 30 to 350 ml (Mayer et al. 2002).
Bertagnoli et al. (2005) reported two cases of retroperitoneal hematomas and a single
subcutaneous hematoma during the perioperative period.
Bone-related changes
Charité III
A single centre involved in the multicentre RCT comparing Charité III versus BAK
surgery reported one patient (1/41, 2%) had significant postoperative heterotopic
ossification (Class 2) with ectopic bone within the disc space, which did not affect
motion (McAfee et al. 2003b).
Blumenthal et al. (2005) reported one case (1/205, 0.5%) of annulus ossification and one
case (1/205, 0.5%) of calcification resulting in bridging trabecular bone.
16
In Muschik & Meergans et al. (2003) one patient (1/39, 3%) had a spinal fusion four
months after Charité III implantation. Caspi et al. (2003) found spontaneous ossification
of the intervertebral anterior ligament in two patients (2/20, 10%), the progression of
which was halted by intensive physiotherapy. In David (2003) there was one patient
(1/21) with incomplete peripheric ossification with no secondary fusion. In their series of
patients with complications, van Ooij et al (2003) found: 12 cases (44%) of degenerative
disc disease at another level (in seven cases this was present before the surgery); one (4%)
spontaneous fusion at the level of the prosthesis eight years postoperatively; 11 cases
(41%) of facet joint arthrosis and three cases (11%)of hyperlordosis of the operated
segment. LeMaire et al. (1997) reported 4% (4/105) of bone complications: one case of
endplate fracture with revision to spinal fusion; one lower endplate subsidence as a result
of osteoporosis; and two cases of periprosthetic ossifications. Cinotti et al. (1996) found
15% (7/46) cases of perianular ossification, stating these did not affect the clinical
outcome.
ProDisc II
No bone-related complications were reported in patients enrolled in the RCT comparing
ProDisc II implantation versus spinal fusion (Delamarter et al. 2003; Zigler 2003).
No perianular ossifications or degenerative changes at levels adjacent the disc
replacement or at the facet joints occurred in Tropiano et al. (2003). In this study mean
lumbar lordosis was 56.7o (range 30-72o) before surgery and 61.9o (range 46-72o) after
surgery. No cases of postoperative fusion were found in Mayer et al. (2002).
Other discs
There were two cases of anular ossification after Acroflex Acromed implantation: one
with autofusion of the joint, the other with angular motion still present on
flexion/extension radiographs. No patients had vertebral endplate erosions, sclerosis,
vertebral boy remodelling or adjacent level disc degeneration.
One late case (1/11) of heterotopic calcification occurred after AcroFlex artificial disc
implantation (Freeman et al. 2001).
There was no evidence of spondylotic bridging of the implant disc space at one year after
insertion of Maverick artificial discs (LeHuec et al. 2003).
17
Potential Cost Impact
Cost Analysis
•
The Charité artificial lumbar disc implant costs approximately $7000 (AUS; two
endplates and one sliding core). This does not include associated costs related to the
surgery itself plus care and rehabilitation of the patient.
•
ECRI have estimated total artificial disc replacement surgery costs between $40,000
and $50,000 (US) (ECRI 2004).
•
It has been recently calculated the direct annual costs of low back pain in Australian
adults is 1.02 billion dollars (AUS) with indirect costs of 8.15 billion dollars (AUS)
(Walker et al. 2003). If intervertebral lumbar disc replacement proves to be effective,
the result may be an overall reduction in cost to the community. However, no formal
cost evaluations have been found.
Ethical Considerations
Informed Consent
Patients should be informed the procedure is still relatively new, and that its longer term
safety and efficacy is not yet properly established. There are no known clinical trials in
Australia involving artificial lumbar intervertebral disc implantation.
Access Issues
The technology is likely to be limited to major centres in Australia.
Training and Accreditation
Training
Surgeons are required to be certified, including attendance of a two day workshop, before
using the ProDisc II artificial disc in Australia (personal communication, Zacks Khan,
Taylor Bryant). Since implantation of an artificial lumbar intervertebral disc is technically
difficult, surgeons should be required to undergo specialist training before performing
the procedure.
18
Clinical Guidelines
No clinical practice guidelines which include lumbar intervertebral disc replacement were
located.
Limitations of the Assessment
Methodological issues and the relevance or currency of information provided over time
are paramount in any assessment carried out in the early life of a technology.
Horizon scanning forms an integral component of Health Technology Assessment.
However, it is a specialised and quite distinct activity conducted for an entirely different
purpose. The rapid evolution of technological advances can in some cases overtake the
speed at which trials or other reviews are conducted. In many cases, by the time a study
or review has been completed, the technology may have evolved to a higher level leaving
the technology under investigation obsolete and replaced.
A Horizon Scanning Report maintains a predictive or speculative focus, often based on
low level evidence, and is aimed at informing policy and decision makers. It is not a
definitive assessment of the safety, effectiveness, ethical considerations and cost
effectiveness of a technology.
In the context of a rapidly evolving technology, a Horizon Scanning Report is a ‘state of
play’ assessment that presents a trade-off between the value of early, uncertain
information, versus the value of certain, but late information that may be of limited
relevance to policy and decision makers.
This report provides an assessment of the current state of development of artificial
lumbar disc replacement, its present and potential use in the Australian public health
system, and future implications for the use of this technology.
Search Strategy Used for Report
A systematic search of MEDLINE®, PREMEDLINE®, EMBASE, Current Contents,
PubMed, Cochrane Library and Science Citation Index was conducted, from the
inception of the databases until September 2004. The York Centre for Reviews and
Dissemination, Clinicaltrials.gov, National Research Register, relevant online journals and
19
the Internet were also searched in September 2004. Searches were conducted without
language restriction.
Articles were obtained if the abstract contained safety and efficacy data on artificial
lumbar disc replacement in the form of randomised controlled trials, other controlled or
comparative studies, case series and case reports. The English abstracts of foreign
language papers were included if they contained safety and efficacy data.
Availability and Level of Evidence
List of studies found:
Total Studies
29
Systematic Review
1
20
Table 6 Studies included in review
Charité III
ProDisc II
Randomised
controlled trials
1
2
Case Series
16
5
Studies identified
but not recovered
1
Maverick
Acroflex
1
2
The papers from the systematic review (de Kleuver et al. 2003) have been included in the
current report, except for one paper by Wittig et al. (1989). This study used the Charité
III artificial disc in 13 patients (14 disc replacements). Follow-up was nine months;
clinical outcomes were not reported, and six of 13 patients required secondary surgery.
A recent Health Technology Literature Review from Canada, including both artificial
cervical and lumbar intervertebral discs, was also found (Medical Advisory Secretariat
2004).
Sources of Further Information
RCTS in progress
RESORD (Randomised European Study on Replacement of the Disc)
Contact Person: Mr ERS Ross, Hope Hospital, Salford UK M6 8HD,
Telephone +44 161 787 1191 or email at [email protected]
ProDisc II IDE Study
The multicentre FDA study was started in the US in October 2001. There are currently
18 US sites participating in a large scale prospective RCT comparing clinical outcomes
between patients receiving circumferential fusions and the ProDisc II total disc
replacement (at a 1:2 ratio) for one- and two-level degenerative disc disease in the
lumbosacral spine L3-S1 vertebral segments. The enrolment goal was 500 patients, with
approximately 300 patients in the US having received a ProDisc implant in January 2003
(Delamarter et al. 2003). The final results from this trial have not yet been published.
Maverick IDE Study
The FDA IDE study was commenced in April 2003. The clinical study will compare the
safety and effectiveness of the Maverick® artificial disc and spinal fusion surgery (2:1
21
ratio) at one level between L4-S1. This study is still recruiting patients
(www.spineuniverse.com 2004).
Flexicore IDE Clinical Study
A US clinical trial for the FlexiCore™ artificial disc was announced in August, 2003 by
SpineCore Inc. (SpineCore 2003).
In July 2004, when Stryker acquired SpineCore Inc., it was stated submission of a PreMarket Approval application to the FDA for the FlexiCore™ was expected to occur in
2007 (PRNewswire-FirstCall/ 2004).
Impact Summary
•
Artificial lumbar intervertebral discs, if successful, could result in substantial gains to
the community as back pain occurs in approximately 79% of Australian adults. Some
patients with severe pain cannot work, and their overall quality of life is poor.
Current surgical options, including spinal fusion, offer limited benefit.
•
Economic gains resulting from artificial lumbar intervertebral discs may be a
consequence of people being able to resume work, and having less pain and
requirement for medical treatments. Social gains include patients having a higher
quality of life, and being able to take a more active role in their community.
•
Despite the potential benefits of artificial disc replacement, ECRI (formerly the
Emergency Care Research Institute) predicted in one of their Health Technology
Forecasts ™ released in June, 2004, that total artificial disc technology will not have
as large an impact as disc nucleus replacement, as the latter can be performed using
minimally invasive techniques (ECRI 2004).
Conclusions
This report has reviewed the current research findings of artificial lumbar intervertebral
disc implantation. Most of the available data relate to two artificial discs: the Charité III
and ProDisc II prostheses.
In a single RCT, Charité III implantation appeared to be superior to BAK surgery in
terms of clinical outcome, such as Oswestry score. A median of 75% of patients had
good to excellent outcomes in 12 case series.
Less evidence was available for the ProDisc II artificial disc, results only available for
individual centres from the ProDisc II RCT. VAS and Oswestry scores appeared to be
reduced more rapidly in patients after ProDisc II versus fusion surgery, however, no
clinical benefits of the artificial disc versus spinal fusion were stated. Clinical success
ranged from 0% to 100% in the four case series.
22
Safety issues relating to implantation of the device were reported in a number of studies.
In the RCT, Charité III implantation did not result in any increase in neurological
adverse events versus BAK surgery. A low incidence (1.5%, 3/205) of device-related
neurological adverse events was reported. Device-related complications ranged from 0%
to 96% in the case series, with 96% reported in a selected group of patients admitted to a
specialist centre with complications after disc replacement surgery. Without this study,
device-related complications ranged from 3% to 10% of patients.
Complications were not well reported in the subgroups of the ProDisc II RCT. In the
three ProDisc II case series with more than two patients, device-related complications
were 0% in two studies and 6% in the third. Total complication rates were 1% to 9%.
Insufficient evidence was available using the Maverick or Acroflex artificial lumbar
intervertebral discs to make any conclusions regarding their safety or efficacy.
Special training is likely to be necessary before surgeons perform this procedure. In the
publication from the Charité III RCT it was stated “artificial disc replacement is one of
the most challenging procedures in spine surgery in the senior author’s experience”
(Geisler et al. 2004).
The correct patient selection appears crucial in gaining the best results from implantation
of artificial lumbar intervertebral discs. Younger patients with single disc disease, limited
degenerative joint changes and without previous spinal surgery are prime candidates for
the procedure. Exclusions would include patients with osteoporosis, facet joint arthrosis
or severe scoliosis. All patients selected for surgery should have proven disc pain eg.
positive provocative discography, and have attempted conservative treatment options for
at least six months.
The development of artificial disc arthroplasty has garnered significant interest from the
medical community but the true safety and effectiveness of these devices are not fully
known. From the studies retrieved, that there is no doubt that these artificial discs are
capable of restoring range of motion to the disc, at least in the short term. However,
restoration of disc range of motion does not always translate to pain relief or improved
function. In addition to this, it is not known if the extra few degrees in range of motion
offered by disc replacement instead of fusion is functionally significant when considering
the motion available at adjacent disc levels and hips. Other concerns include the
resilience of these artificial disc towards wear and tear, a disc prosthesis may be expected
to withstand more than 100 million cycles in its lifetime and no artificial disc models have
been tested this extensively (Frazer et al. 2003). In addition to this, adjacent level
degeneration after disc replacement has not been studied extensively, the assessment by
Cinotti et al. (1996) where no adjacent level degeneration was identified at 2 years followup is somewhat misleading when more than 75% of their original cohort was not
investigated (Fraser et al. 2003). Further studies will be needed to fully assess the factors
influencing the outcomes of lumbar intervertebral disc replacement, and the safety and
efficacy of the procedure.
23
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28
Appendix A: Table of Key Efficacy and Safety Findings
Charité III
Study details
Key efficacy findings
Key safety findings
Appraisal/Comments
Randomised Controlled Trial (Charité III)
Geisler et al. 2004, USA
(studies included: McAfee et al. 2003a
and 2003b; Blumenthal et al. 2003
304 patients
Charité: n=205
BAK: n=99
14 clinical centres
Charité
L4/L5
61/205
(29.7%)
L5/S1
144/205
(70.3%)
No intergroup differences.
BAK
32/99
(32.3%)
67/99
(67.7%)
Follow-up: Clinical and radiographical
evaluation at 6 weeks and 3, 6, 12 and 24
months.
Implant: SB Charité III
Comparison: Patients had Charité disc
replacements (Charité) or lumbar
interbody fusion involving BAK cages
and iliac crest bone graft (BAK).
Selection criteria: Primary inclusion
criteria included: single-level
degenerative disc disease at L4/L5 or
L5/S1 confirmed by MRI and
provocative discography; age 18 to 60
years; ODI score ≥ 30; back pain VASrated score ≥ 40 with no radicular
component (referred leg pain was
Neurological changes
Neurological
status: change
from baseline
6 months
No change
Significantly
improved
Slightly
improved
Slightly
deteriorated
Significantly
deteriorated
total
missing
12 months
No change
Significantly
improved
Slightly
improved
Slightly
deteriorated
Significantly
deteriorated
total
missing
24 months
No change
Significantly
improved
Slightly
improved
Slightly
deteriorated
Significantly
deteriorated
total
Adverse neurological events (NAEs):
Charité
No (%)
BAK
No (%)
147 (77)
6 (3)
67 (76)
5 (6)
27 (14)
9 (10)
9 (5)
4 (5)
1 (1)
3 (3)
190
15
88
11
153 (82)
5 (3)
61 (75)
2 (2)
19 (10)
12 (15)
8 (4)
6 (7)
2 (1)
0
187
18
81
18
141 (79)
2 (1)
65 (82)
0
19 (11)
10 (13)
13 (7)
3 (4)
4 (2)
1 (1)
179
79
Factor
No of NAEs
No of patients with
NAEs
Major NAE
burning or
dysesthetic leg pain
motor deficit in
index level
nerve root injury
Minor NAE
numbness in index
level
numbness in sacral
nerve distribution
Other NAE
numbness in
peripheral nerve or
nonindex level
positive Waddell
signs
reflex change
mechanical signs
(straight leg raising
test)
Charité
No (%)
38
34 (16.6)
BAK
No (%)
20
17 (17.2)
10 (4.9)
5 (2.4)
4 (4.0)
3 (3.0)
4 (2.0)
1 (1.0)
1 (0.5)
20 (9.8)
20 (9.8)
0
8 (8.1)
7 (7.1)
0
1 (1.0)
8 (3.9)
5 (2.4)
8 (8.1)
4 (4.0)
1 (0.5)
1 (1.0)
2 (1.0)
0
2 (2.0)
1 (1.0)
Device-related neurological events:
No of NAEs
Charité
No (%)
3 (1.5)a
BAK
No (%)
0
a: one event (nerve root injury) was classified as
severe.
Bleeding:
In approximately two thirds of the cases during disc
space distraction, some epidural bleeding or
Potential for Bias:
Randomisation was performed according
to a random number generator. (McAfee
et al. 2003a). The method of allocation
concealment was not stated.
In one of the centres involved in the study
an independent nurse practitioner of
physician’s assistant interviewed the
patient and administered the Oswestry
and VAS scores. (McAfee et al. 2003a)
At 6 months there were 190 Charité III
and 88 BAK patients; at 12 months 187
Charité III and 81 BAK patients; and at
24 months 179 Charité III and 79 BAK
patients remained. There were more
patients missing in the BAK (20/99, 20%)
versus Charité III groups (26/205, 13%)
which may have biased the result.
There were no significant differences in
age or sex between the two groups.
Outcome measures and their validity:
All outcome measures used were well
validated.
Other comments:
“…precise placement is crucial to the
proper functioning of the Charité
prosthesis. For best results and to mimic
the normal instantaneous axis of rotation
of a normal intact disc, the Charité device
must be placed approximately 3 to 3 mm
posterior to the center of the disc space
and as close to the exact center as
possible in the coronal plane. Large
29
permitted); and failed nonoperative
treatment of at least 6 months duration.
Primary exclusion criteria: Previous
thoracic or lumbar fusion; multilevel
degenerative disc disease; facet joint
arthrosis; noncontained herniated nucleus
pulposus; osteoporosis; spondylolisthesis
slip >3mm; scoliosis > 11o; and
midsagittal stenosis < 8mm.
missing
26
20
No significant intergroup differences.
ODI score:
Mean
preoperative
24 months
Mean
change
Charité
54.6
(n=205)
25.8
(n=179)a
-24.8
BAK
52.1
(n=99)
30.1
(n=79)
-22.0
From McAfee et al. 2003 (n=60: Charité n=41, BAK
n=19)
a: number extrapolated from patients remaining at
24 months.
At all time points the ODI score was significantly
reduced in the Charité patients.
There was a significant difference in the Charité
versus BAK ODI scores at 3 and 6 months, but not
from 12 months.
25% improvement in ODI score:
24 months
Charité
62%
(n=179)
BAK
49%*
(n=79)
*: p=0.0354; numbers extrapolated from total
patients.
There were significantly more patients with an
improvement in ODI score of 10 points or more
from 3 to 24 months in the Charité versus BAK
patients (p<0.05).
VAS score:
Mean
preoperative
24 months
Mean
change
Charité
72 (n=205)
BAK
71.8 (n=99)
30.6
(n=179)a
-41.4
(-57.5%)
36.3 (n=79)
-35.5
(-49.4%)
a: number extrapolated from patients remaining at
24 months.
20 point improvement in VAS score:
24 months
Charité
65%
(n=179)a
significant bone bleeding along the posterior edge
occurs, which was easily managed by placing strips
of Avitene in the disc space and compressing them
down against the remaining posterior longitudinal
ligament.
BAK
56%*
(n=79)
Estimated blood loss (McAfee et al. 2003):
n=60: Charité n=41, BAK n=19
Mean 289.5 ml (range 50-1800 ml)
Mortality:
One death unrelated to the spinal procedure (? group).
Other complications:
In the Charité group there were no dislodgements of
the prostheses, no cases of significant subsidence, no
evidence of prosthetic loosening and no late
infections.
deviations from this placement may yield
less than ideal results.”
This trial has been criticised for using
BAK surgery as a comparison, as this is
no longer the best method of fusion, but a
literature search was included in the study
to provide results from other forms of
fusion surgery.”
“At the time of publication, new thirdgeneration instrumentation for
implantation of the Charité device will
allow for an intuitive, straightforward
implantation of the prosthesis.”
Discography should be performed prior to
any form of artificial disc replacement.
It was stated “surgeon training is essential
for good clinical and functional
outcomes”.
The study protocol indicated surgeons at
each study site should perform five
training cases prior to randomisation (71
training cases were performed).
One patient had postoperative small bowel
obstruction of uncertain origin: (? group). Found
adhesions of greater omentum at surgery, now use of
the self-retaining Thompson retractor to retract the
bowel is ‘curtailed’.
One patient had significant postoperative heterotopic
ossification (Class 2), with ectopic bone within the
disc space which did not affect motion.
In the total cohort there was one case each of:
retrograde ejaculation, depression, adynamic ileus
requiring a nasogastric tube, adynamic ileus
spontaneously resolving without a nasogastric tube,
one urinary tract infection, one case of epididymitis,
one case of lateral epicondylitis and one case of
degenerative changes at the vertebral level above.
From Blumenthal et al. 2003 (n=57 first consecutive
Charité cases)
30
*: p=0.1028; a: number extrapolated from patients
remaining at 24 months.
Flexion-extension range of motion:
24 months
Charité
7.4 ± 5.28o
(n=179)a
BAK
1.1 ± 0.87o
(n=79)
Blood loss (ml):
L4-L5
L5-S1
All levels
n=12
n=45
n=57
265.9
101.4*
134.3
*: p<0.05 versus L4-L5 level
Mean ± SD; a: number extrapolated from patients
remaining at 24 months.
Re-operation:
No patients in either group required additional
spinal reconstructive procedures at 1 to 3 years
follow-up.
From McAfee et al. 2003 (n=60: Charité n=41,
BAK n=19)
Surgery length
Mean 88.4 minutes (range 57-137)
Hospital stay
Mean 3.03 days (range 2-6)
From Blumenthal et al. 2003 (n=57 first
consecutive Charité cases)
Operating time (min)
L4-L5
L5-S1
n=12
n=45
95.2
74.4*
*: p<0.05 versus L4-L5 level
All levels
n=57
78.7
31
Study details
Randomised controlled trial
Blumenthal et al. (2005) USA
Prospective, randomized, non-blinded, FDAapproved study at 14 investigational sites in USA.
304 patients (Investigational group: 205, control
group: 99)
Follow-up: Clinical assessments were conducted
at 6 weeks prior to surgery and at 3, 6, 12 and 24
months post-surgery.
At 12 months the follow-up rate was 95.8% of the
investigational group and 94.2% of the control
group. At 24 months 91.5% of the investigational
group and 89.2% of the control group were
available for assessment.
Implant: SB Charité III (DePuy Spine,
Johnson&Johnson, Raynham, MA, USA)
Selection criteria:
Single-level symptomatic degenerative disc
disease at L4-L5 or L5-L1 confirmed by
provocative discography, back and/or leg pain
without nerve root compression (radiculopathy)
with a visual analog scale (VAS) score ≥40 and an
ODI score ≥30, ability to tolerate an anterior
abdominal approach, and failure to respond to
nonfusion treatment for a period of 6 months.
Exclusions:
Previous thoracic or lumbar fusion, current or
prior fracture at L4,L5, or S1, symptomatic
multilevel disc degeneration, osteoporosis,
spondylolisthesis >3mm, spondylosis, and
scoliotic deformity >11º.
Key safety findings
Appraisal/Comments
Surgery
No significant difference was noted between the two
patient groups for mean operative time and mean blood
loss.
Complications
The incidences of
neurological complications
were not different between
groups.
Potential for bias
Random allocation of patients was
done by a contract research
organisation using SAS software in a
2:1 ratio.
Pain in bone graft donor site
was experienced by 18
(18.2%) control patients.
The investigator, key office staff and
operating room staff were not blinded
to group assignment.
Patients were only blinded until after
the surgery. This may have affected
the results of the patient’s satisfaction
survey.
Hospital stay was significantly lower (p=0.0039) for the
investigational group (3.7 days) versus the control group
(4.2 days)
Mean Oswestry Disability Index
Period
Preop.
Mean
%imp from preop
6 wks
Mean
%imp from preop
3 months
Mean
%imp from preop
6 months
Mean
%imp from preop
12 months
Mean
%imp from preop
24 months
Mean
%imp from preop
Investigational
Control
50.6
0
52.1
0
37.7
23.9*(**)
43.7
12.7*(**)
29.9
40.2*(**)
37.4
25.7*(**)
27.5
46.2*(**)
35.8
30.8*(**)
26
48.8*(**)
31.8
37.9*(**)
26.3
48.5*
30.5
42.4*
Device failures occurred in 11
(5.4%) investigational
patients and 9 (9.1%) control
patients.
Approach related
complications occurred in 20
(9.8%) investigational group
patients and 10 (10.1%)
control group patients.
Overall complication rates did
not differ between groups.
validated.
Other comments
At 24 months, 185 patients were
available for assessment in the
investigational group while 82
patients were available in the control
group.
Note: * indicates significant difference of Intra group to preop;
(**) indicates significant difference between groups
32
Mean Visual Analog Scale Scores
Period
Preop.
Mean
%imp from preop
6 wks
Mean
%imp from preop
3 months
Mean
%imp from preop
6 months
Mean
%imp from preop
12 months
Mean
%imp from preop
24 months
Mean
%imp from preop
Investigational
Control
72
0
71.8
0
36.4
35.9*(**)
44.1
27.7*(**)
35.7
35.7*(**)
44.5
27.4*(**)
33.1
39*(**)
43.9
28.2*(**)
32.9
39.1*(**)
40.4
30.9*(**)
31.2
40.6*
37.5
34.1*
Note: * indicates significant difference of Intra group to preop;
(**) indicates significant difference between groups
Patient Satisfaction
Period
12 months
24 months
Investigational
71.3%
73.7%
Control
59%
53.1%
No significant difference was observed between the two
groups with regards to patient satisfaction (p = 0.0559).
Whether patients would undergo the same treatment
Period
12 months
24 months
Investigational
73.4%
69.9%*
Control
57.7%
50.0%
The investigational group had significantly higher
33
proportion of patients who would have the same
treatment again compared to the controls at 24 months
(p=0.0063).
Clinical success
Overall clinical success was achieved in 57.1% of
patients in the investigational group and 46.5% in the
control group (p<0.0001).
In a subgroup of patients who completed 24 months
follow-up, significantly higher clinical success was
noted in the investigational group (63.6%) compared to
controls (56.8%) (p=0.0004).
Rate of clinical success (defined by ≥25% improvement
in ODI scores at 24 months compared to preop scores)
was significantly higher in the investigational group
(63.9%) compared to the controls (50.5%) (p=0.0338).
Narcotic medication use
Investigational
Control
p=0.0083
Proportion of patients using
narcotics to control pain (overall)
72.2%
85.9%
In subgroup of patients who achieved clinical success:
Investigational
Control
p=0.0428
Proportion of patients using
narcotics to control pain (at 24
months)
64.0%
80.4%
34
Study details
Key safety findings
Appraisal/Comments
Randomised controlled trial
McAfee et al. (2005) USA
Operative level Range of Motion (ROM)
None stated
Potential for bias
The randomisation process was the
same as Blumental et al. (2005). This
study was performed on the same
patient cohort.
Prospective, randomized, non-blinded, FDAapproved study at 14 investigational sites in USA.
304 patients (Investigational group: 205, control
group: 99)
Follow-up: Clinical assessments were conducted
at 6 weeks prior to surgery and at 3, 6, 12 and 24
months post-surgery.
Mean ROM was equivalent in both groups pre-surgery.
At 3 months post-surgery, ROM decreased in both
groups. However, ROM for the investigational group
began to increase from months 6 to 24.
ROM for the control group continued to decrease from
months 6 to 24.
At 6 months, ROM in the investigational group was
92.4% of pre-operative ROM.
At 24 months, ROM in the investigational group was
113.6% of pre-operative ROM.
Surgical Placement
Selection criteria:
Single-level symptomatic degenerative disc
disease at L4-L5 or L5-L1 confirmed by
provocative discography, back and/or leg pain
without nerve root compression (radiculopathy)
with a visual analog scale (VAS) score ≥40 and an
ODI score ≥30, ability to tolerate an anterior
abdominal approach, and failure to respond to
nonfusion treatment for a period of 6 months.
Exclusions:
Previous thoracic or lumbar fusion, current or
prior fracture at L4,L5, or S1, symptomatic
multilevel disc degeneration, osteoporosis,
spondylolisthesis >3mm, spondylosis, and
scoliotic deformity >11º.
validated.
Other comments
A mean ROM of 7.5º was reported at
24 months. This includes subjects
with suboptimally placed Charite
discs, therefore suggesting that the
disc is quite forgiving in terms of
placement and proper function.
At 24 months follow-up:
82.9% of patients were graded as having ideal
placement (Group I)
10.7% were graded as having suboptimal placement
(Group II)
6.2% were graded as having poor placement (Group III)
However, the authors stated that if
the placement is poor enough to be
5mm or more off axis in wither the
midsagittal or coronal planes, the
flexion/extension ROM will be
negatively affected.
Correlation of surgical placement with clinical
outcomes
Mean ODI scores (at 24 months) improved with the
degree of technical accuracy.
Technical accuracy groups
Group I
Group II
Group III
P<0.05
Mean ODI
24.1
30.3
36.3
35
Mean VAS scores (at 24 months) improved with the
degree of technical accuracy.
Group I
Group II
Group III
p=0.016
Mean VAS
28.3
35.4
48.4
Correlation of surgical placement with operative level
ROM
Group I
Group II
Group III
Flexion/extension
ROM
7.12º ± 4.06º
7.47º ± 4.41º
3.15º ± 3.51º
A significant difference was observed between both
ideal (group I) and suboptimal (group II) and poor
placement (group III) regarding flexion/extension ROM
(p=0.003).
Disc space height and subsidence
The Charite disc was significantly more effective than
the BAK controls in restoring height of the collapsed
disc space at L4-L5 and L5-S1 (p<0.05).
36
Study details
Key safety findings
Appraisal/Comments
Migration of disc:
2/20 (2 days after surgery due to
incomplete severing of the postlongitudinal ligament in 1 patient and
2 weeks post-surgery due to small
fracture of the lower endplate in the
other).
Potential for bias:
It was not stated whether the patients were
consecutive or a selected group.
Case series
Caspi et al.6 2003, ISRAEL
n=20 (23 prostheses)
Segment
No
L4/L5 and L5/S1
3
Single level
17
Follow-up: 48 months
Selection criteria: All patients had suffered low
back pain with/without radicular pain for at least 5
years. Three patients had undergone previous
surgery by a posterior approach. Preoperative Xrays showed narrow disc space and discography
as a pain provocative and memory test was
performed in all patients. MRI was used to
analyse the diseased disc and to eliminate a
residual posterior compression from scar tissue in
the failed back that was operated on.
Clinical results:
Result
No
Excellent
11
Good
4
Fair
3
Poor
4
Total patients add up to 22?
a: 1 patient had secondary fusion and 1 is
waiting for surgery. “The postoperative Xrays showed good results, and after further
investigation it became apparent that all
four were in different stages of ligation.”
(it is uncertain what the authors mean by
‘ligation’)
Return to work:
Completely disabled
Resumed physical
labour
Returned to light and
sedentary work
No
4
1
15
Range of segmental motion:
Average 3-9o
Device Failure:
There was a small fracture of the
lower endplate (leading to disc
migration) in 1 patient.
Spontaneous ossification of the
intervertebral anterior ligament:
Observed in 2 patients, its progression
was halted by intensive
physiotherapy.
Intraoperative laceration
of the ureter and
thrombosis of the iliac
artery
Infection
Sexual complications
Outcome measures and their validity: There
was no mention of how the clinical results
were obtained, whether it was the patients’
subjective feelings or if a validated grading
system was used.
Other comments: It was stated that the largest
possible disc prosthesis was chosen for
insertion (in most cases measuring 9.5mm).
“The main indication for lumbar disk
prosthesis is chronic lower back pain due to
disk degeneration in young patients (up to
age 55). The lumbar disk prosthesis is
indicated for patients under the age of 55 due
to bone quality and status of posterior facet
joints.”
No
1
0
0
Re-operation:
2/20 (10%) because of disc migration,
larger prostheses were implanted.
29
Study details
Key safety findings
Appraisal/Comments
Measures of Pain:
No measures of pain reported. Only one
patient had moderate radicular pain in the
long term (much less than after recurrent
posterior surgery).
Complications:
One case of epidural vein bleeding
and one case of incomplete peripheric
ossification with no secondary fusion.
Potential for bias:
The method of patient selection was not
stated, therefore whether the patients are
likely to have been a biased sample could not
be assessed.
Case series
David 2003, FRANCE (abstract)
n=21
Segment
L5/S1
L4/L5
No
14
7
Operated on between 1993 and 2001
Follow-up: Average of 4 years
Selection criteria: Patients with severe sciatica
with a recurrent hernia two years (on average)
after posterior surgery for disc hernia at the same
level. All had chronic low back pain with a fair
result after the first surgery. Hernia confirmed by
MRI and discography-CT; sometimes through the
posterior ligament but the disc was not extruded.
Some patients had some bone reaction (n=9;
Modic sign).
Mobility:
All prostheses had on average 12o on
flexion/extension films and 5 o on
bendings.
Work:
19/21 (90%) of patients recovered and
returned to the same job.
Stauffer-Coventry-Cauchoix classification:
Excellent: 9/21 (43%)
Good: 12/21 (57%)
The Stauffer-Coventry Index is a clinical
surgical outcome measure, designed for
administration after surgery and consisting of
four multiple choice self-report questions
regarding pain reduction, return to work,
limitations of physical activities and
medication usage. (assumed the StaufferCoventry-Cauchoix classification is a French
version of this, but could not find further
information)
Other comments: This study was in abstract
form only, limiting the amount of
information about the study.
30
Study details
Key safety findings
Appraisal/Comments
Operating time:
Mean 180 minutes
Blood loss:
Mean 300 ml
Outcome: All four patients with
neurological compromise had marked
improvement of symptoms within
their hospital stay, with improvement
maintained to the last follow-up.
Perioperative complications:
None
Potential for bias:
This was a small group of only five
patients. These patients were selected
from 11 patients with surgery, and it is
possible the 6 patients not included had
poorer outcomes.
Case series
Kim et al. 2003, KOREA
n=5 (11 patients had surgery but results only given for 5)
Surgery since January 2002
Segment
No
L1-L2
1
L3-L4:
2
L5-S1
1
L3-L4-L5:
1
(except for one patient, all juxtafusional degenerations were
superior to the previous fusion or nonunion)
Follow-up: Radiographs taken on day 1 and at 1,3, 6 and
every 6 months postoperatively. Follow-up > 6 months in all
patients.
Implant: SB Charité III (DePuy Spine, Johnson&Johnson,
Raynham, MA, USA)
Selection criteria: Patients with symptomatic juxtafusional
degeneration syndrome undergoing surgical treatment have
had artificial disc replacement unless contraindicated.
Indications were neurologic disturbance (neurogenic
intermittent claudication, radiculopathy) and/or severe back
pain compromising the activities of daily living and not
responding to prolonged conservative treatment of ≥ 6
months. All patients had radiographs, bone mineral density
measurements, lumbar MRI and CT scans before surgery.
Exclusions: target level higher than L1-L2, fractured
vertebral body, severe facet joint degeneration, posterior
element incompetence resulting in antero retrolisthesis,
infection, significant spinal misalignment or disc space
tilting and/or wedging in the coronal and sagittal plane, and
negative provocative discography.
ODI Score:
Preoperative
1 month
3 months
6 months
64%
31%
25%
24%
Technical failure:
None requiring re-operation, and no
implant subsidence or dislocation at 6
months follow-up.
Outcome measures appeared to be
using well accepted measures.
Other comments:
MacNab’s criteria:
Overall clinical improvement using
MacNab’s criteria was excellent in
three and good in two patients at 6
months follow-up.
Re-operation:
There were no technical failures or
complications that needed a reoperation.
31
Study details
Key safety findings
Appraisal/Comments
Clinical improvement:
Complete or satisfying improvement:
DDD
PNS: 4/10
23/29 (79%)
4/10 (40%)
Improved in part:
DDD
PNS
0/29 (0%)
2/10 (20%)
No benefit:
DDD
PNS
6/29 (21%)
4/10 (40%)
Complications:
There were 10% complications in both
groups, including 2 fractures of a small
fragment of the dorsal wall of the vertebral
body, 1 posterior subluxation of the
implant, 1 fusion after 4 months.
Potential for Bias:
Study is in abstract form only with minimal
detail of the procedures and results. It was not
stated how patients were selected.
Case series
Muschik & Meergans 2003, GERMANY
39 patients
29 with degenerative disc disease (DD) and 10
with postnucleotomy syndrome (PNS)
2000 to 2002
Segment
No
L5/S1
27
L4/L5
8
L4/L5 and L5/S1
4
Follow-up: 2 + 1 years (not sure if 1 year is the
SD)
Comparison: Patients having Charité disc
replacements had either degenerative disc disease
(n=29) or postnucleotomy syndrome (n=10).
Selection criteria: Patients whose operation was
< 12 months ago were excluded.
Mobility:
DDD
PNS
8+2o
6+2o
Note type of variance not stated.
Neurological deficits:
No neurological deficits were observed in
either group.
Details of the types and methods of testing
were not included in the abstract.
Other comments:
Authors conclude the indications for artificial
disc replacement in patients with
postnucleotomy syndrome ‘remain unclear’.
Relordisation of operated segments:
DDD
PNS
9o
9o
Re-operation:
1/39 (3%) because of a posterior
subluxation of the implant.
32
Study details
Key safety findings
None stated
Intraoperative complications:
Appraisal/Comments
Case series
Pimenta et al. 2003, BRAZIL
n=55 (67 implants)
January-December 2002
Segment
No
L2/L3
1
L3/L4
4
L4/L5
30
L5/S1
32
1 replacement
2 replacements
3 replacements
No
44
10
1
Endplate fracture due to excessive
distraction
Iliac vein lesions
Ureter lesion
No
1
2
1
Postoperative complications:
Abdominal hernia
Implant subsidence
Seroma
Transitory premature ejaculation
Foraminotomies due to fibrosis (in
cases of previous spinal surgery)
No
1
2
1
1
2
Potential for bias:
Study is published in abstract form
only, limiting the amount of
information which was given.
Limited outcomes were given and no
efficacy outcomes were reported.
Other comments:
The authors state ‘we recommend intraoperative assistance of a surgeon
experienced in the retroperitoneal space
to avoid possible eventualities.’
Follow-up: 1 to 11 months
Selection criteria: Patients had degenerative disc
disease (n=35), previous spinal surgery (n=7),
pathology on the vertebra adjacent to fusion (n=6),
previous failed PDN (n=4), isthmic
spondylolisthesis (n-2) and a non-union at the level
of fusion (n=1).
Cases related to prosthesis:
n=2 (4%)
Cases related to any spinal surgery:
n=9 (16%)
33
Study details
Key safety findings
Appraisal/Comments
Clinical outcome:
Result
No (%)
Excellent
23/31 (74%)
Good
6/31 (29%)
Fair
2/31 (10%)
Disc displacement:
A slight displacement of the core
occurred in one case without any
clinical symptoms and signs.
Potential for bias:
This study was available only in
abstract form, it was difficult to
determine if the patient group was
biased and how patients were selected.
Case series
Su et al. 2003, CHINA
n=31 (37 discs)
April 1998 to April 2000
Follow-up: Mean 26 months (range 17 to 41 months)
Implant: SB Charité III (DePuy Spine, Johnson&Johnson,
Raynham, MA, USA)
Selection criteria: Patients had lumbar disc degenerative
diseases and lumbar disc herniation with disc space
narrowing.
No
Disc degenerative disease
16 (18 discs)
Disc herniation with disc
13 (17 discs)
space narrowing
Recurrent disc herniation
2
Mobility of operated area:
Degrees
Anterior flexion
4.0
Posterior flexion
5.1
Total
9.1
Intervertebral disc space:
Operated disc space was an average
of 4.2 mm higher than before surgery.
The method of measuring clinical
outcome was not stated, it may have
been only a subjective measure.
Other comments:
.
34
Study details
Key safety findings
It was stated there was a “lack (of)
information concerning the pain level and
functional status prior to the disc
replacement, but all patients told us that
they preoperatively suffered serious and
constant back pain and leg pain for
considerable time periods”.
Early complications:
Complication
No
Dislocation of disca
1/27
Abdominal wall/ retroperitoneal
4/27
haematoma
Retrograde ejaculation, libido loss,
1/27
erectile dysfunction/hypoaesthesia
Erectile dysfunction
1/27
(without retrograde ejaculation)
Asymmetrical insertion
1/27
(with no pain relief)
a: L5-S1 prosthesis dislocated anteriorly within 1 week.
9/27 (33%) of patients had early complications.
Appraisal/Comments
Case series
van Ooij et al. 2003, THE
NETHERLANDS
n=27 early (n=26 late)
1995Segment
No
L4/L5
12
L5/S1
6
L2/L3
1
L3/L4
1
L4/L5 and L5/S1
5
L3/L4, L4/L5 and L5/S1
1
L5/L5 (?L4/L5)
1
3
L4/L5a
a: preceded by an anterior fusion of
L5/S1
Preceding the surgery:
Percutaneous nucleotomy of the same
level: n=3
Posterior undercutting facetectomy: n=2
Herniated disc surgery: n=1
Follow-up: Mean 53 months (range 11127 months)
(Mean 91 months, range 15-157 months,
in 26 patients with mid- and long-term
evaluation)
Selection criteria: Patients at a tertiary
university referral center with persisting
back and leg complaints after a disc
prosthesis at another institution.
Good initial result:
12/26 (46%; 1 month to 10 years)
No benefit:
14/26 (54%)
(In one patient there was early
subluxation of the prosthesis)
Re-operation:
15/27 (56%)
Removal of prosthesis in 4 patients and a
second spinal reconstructive salvage
procedure in 11 patients.
Late complications:
Complication
No
Degenerative disc disease at another
12a
level
Fusion at level of prosthesis
1b
Facet joint arthrosis
11
Subsidence of the prosthesis
18c
Subluxation
1d
Anterior migration of the prosthesis
2e
Prosthetic wear
1f
Breakage of metal wire around the
2
polyethylene core
Hyperlordosis of the operated
3g
segment
100% of patients had late complications.
a: in 7 patients degeneration was obvious on X-rays before
the operation and in 7 patients adjacent level degeneration at
previously sound levels was present after surgery.
b: after 8 years of pain relief spontaneous fusion led to new
symptoms, probably because of disc degeneration 2 levels
higher.
Potential for bias:
These patients were a selected
group with complications, the
total number of patients
operated on at the other
institution was not stated, and
therefore the incidence of
complications could not be
calculated.
Outcome measures and their
validity: No real efficacy results
were given; the results given
appeared to be subjective and
did not use standardised
measures such as the VAS
score.
Other comments: No data were
available on the pain level and
functional status of the patients
prior to surgery.
35
c: in 10 cases the prosthesis was definitely too small, and of
adequate width and depth in 8 cases; the polyethylene core
was radiographically never dislocated out of the metal plates)
d: the core subluxated anteriorly and the L4-L5 segment
above a formerly fused L5-S1 segment was blocked in
extension.
e: causing compression of the great vessels in 1 patient, the
prosthesis was removed after 10 years; in 1 patient a
posterior fusion was recently performed.
f: after > 13 years the prosthesis at L4-L5 is showing
radiological signs of wear, being subsided into L4 and
surrounded by extensive sclerosis; CT scans showed
fragmentation of surrounding bone and cyst formation,
analogous to polyethylene wear effects around hip
prostheses; the patient is severely handicapped but refuses
further surgery.
g: resulting in an opening of the facet joints in the superior
part and a compression in the inferior part of the joints; this
could be a cause of later facet joint arthrosis).
36
Study details
Key safety findings
Appraisal/Comments
Pain postoperatively:
General
Pain-free
Reduction in pain
No pain relief
Leg Pain
Reduction in
patients with
preoperative pain
Negative straight
leg test
Recovered motor
symptoms
Total complication rate:
General or specific complications: 9/20 (45% )
Potential for Bias:
How patients were allocated to the
groups was not stated.
Case series
Buttner-Janz et al.5 2002, GERMANY
20 patients
(14 unisegmental, 6 bisegmental
replacements)
Follow-up: 46 months (6 months to 13
years)
Selection criteria:
All patients- postnucleotomy syndrome
No
25% (5/20)
70% (14/20)
5% (1/20)
83% (15/18)
93% (14/15)
40% (2/5)
Segmental/sagittal total range of motion:
Unisegmental: implantation mean 6.8o (range
0-20o)
Bisegmental implantation: mean 5.8o (0-14 o)
in second disc segment.
Neighbouring segments with the best function
had a range of motion of 6.8o
Validity of outcome measures (general
pain, leg pain and ROM) are difficult
to ascertain from abstract alone
Other comments:
Authors note the ‘stated general and
specific complications had a definite
influence on the results in one patient
and a questionable influence on a
second patient’ suggesting that
complications related to the device are,
in reality, lower than 45% (i.e.
2/20=10%)
37
Study details
Key safety
findings
Appraisal/Comments
Analgesia Requirement:
NSAID use decreased from 33 patients to 5 patients
postoperatively.
Blood loss:
Mean 125 ml
Potential for bias:
Losses to follow-up noted (i.e. 25/35 patients
had an angle of lordosis measurement).
Patients were prospectively studied.
Case series
Hopf et al.6 2002, GERMANY
35 patients (24 unisegmental, 11 bisegmental).
Follow-up: mean 14.7 months.
Selection criteria:
Unsuccessful conservative management of low
back pain > 6 month.
Age < 45 years, radiologic evidence of DDD with
or without disc prolabation and positive for
preoperative diagnostic measures.
Scott-Young & Tan et al.7 2002, AUSTRALIA
(abstract)
86 patients (113 prostheses)
Results from one surgeon since 1996.
Follow-up: mean 20 months (range 2 months to 5
years)
Selection criteria: None stated
Angle of Lordosis (L1-S1):
Mean increased from 35.6 degrees to 42.6 degrees
(20.2% increase)
How the angles of movement were measured
was not reported
Length of hospital stay:
Mean 16.8 days
Other comments:
Authors note that ‘indication in patients with
failed back surgery cannot be estimated yet’.
They also note that ‘improvements of the
instrumentation are mandatory’.
Operating time:
Mean 85.5 minutes
Segmental Angle:
Increased from an mean of 19 degrees to 30 degrees
(57.5% increase)
Results:
Good to excellent
84%
Complications:
“Complications have the
potential to be
catastrophic but attention
to surgical detail results in
minimal complications
which will be discussed in
the body of the
presentation.”
Potential for Bias:
It was not stated whether the patients were
consecutive or a selected group. One surgeon
performed all procedures, negating any intersurgeon variability.
Questionnaires including Roland-Morris and
Oswestry, Visual Analogue Scores and SF36
Data were collected, but these results were
not stated.
The method of measuring the ‘good to
excellent’ results was not stated.
Other comments: It is difficult to analyse the
study as it is only in abstract form.
38
Study details
Case series
Sott et al.7 2000, UK
14 patients (with 15 prostheses).
Follow-up: mean 48 months (range 18-68
months).
Selection criteria:
Patients with DDD accompanied by
segmental instability.
Key safety findings
Appraisal/Comments
Overall patient-reported outcome:
(pain relief, return to employment and/or general
physical activity):
Result
No
Good
71% (10/14)
Fair
14% (2/14)
Poor
14% (2/14)
No major complications.
Some minor complications.
Potential for Bias:
Small sample size, it was not stated if the
patients were consecutive or not.
Outcome grouped by greater or less than 45 years
of age did not influence outcome.
Disc height restored in all cases.
1 patient – warmer left foot due to
interference with left paravertebral
sympathetic nerves.
Implant migration:
7% (1/14) lower prosthetic endplate
had sunk by 3 mm.
Stauffer and Coventry and Oswestry
Disability scoring systems were used.
Other comments:
Authors noted that ‘in contrast to prior
publications, age >45 years did not appear to
adversely affect outcome’.
39
Study details
Case series
Zeegers et al.8 1999, THE
NETHERLANDS
50 patients (29 patients
unisegmental, 18 bisegmental
and 3 trisegmental)
Follow-up: minimum 2 years
Implant: SB Charité III (DePuy
Spine, Johnson&Johnson,
Raynham, MA, USA)
Selection criteria:
Patients with ‘symptomatic
discopathies’; 54% had
undergone previous spinal
surgery.
Key safety findings
Appraisal/Comments
Satisfactory clinical result:
32/46 (70%)
Patients <45 years had a significantly better outcome.
Result
No
Complications related to anterior approach:
15% of patients had side-effects or
complications of a more permanent character.
Potential for bias:
Four patients lost to follow-up, this
may have influenced the strength of
some of the efficacy findings.
Patients were studied prospectively
and all operated on by the same
surgeon, negating any inter-surgeon
variability. It was not stated if the
Improvement in leg pain at 2
years
64% (27/42)
Improvement in low back
65% (30/46)
pain
Returned to work
81% (35/43)
Able to reduce their analgesia
44% (15/34)
Patients with no previous surgery and no other
degeneration of spinal disorder (apart from symptomatic
discopathy) had a positive clinical result of 80% at 2 year
follow-up.
Radiographic result at 2 years:
Result
No
Good
74% (28/38)
Fair
24% (9/38)
Malpositioned implant
5% (2/38)
Asymmetric position,
18% (7/38)
clinically acceptable
Hospital stay:
All patients had supine bedrest for an average of 4 days
(range 0-45 days) followed by a mean time to mobilization
of another 7 days (range 1-45 days). Total hospital stay
averaged 10 days (range 3-90 days) according to the
protocol of the period.
Range of motion:
Flexion-extension range on lateral radiographs averaged
9o (range 2-17o) 2 years postoperatively (preoperative
range of motion was an average of 9o, range 2-20o).
Complications up to 2 years after surgery:
Temporary Permanent
n=44
n=8
Neurological (n=10)
Dysaesthesia of
4
3
legs
Paresis/muscle
1
—
weakness
Cramps in legs
2
—
Wound/haematoma (n=17)
Painful/numb
5
—
scar
Haematoma
12
—
Abdominal problems (n=3)
Retroperitoneal
1
—
haematoma
Visceral
1
—
dysfunction
Abdominal pain
1
—
New or progression of old pain (n=5)
Low back or
5
—
leg pain
Vegetative dysfunctions (n=8)
Sympathectomy
3
4
effect
Disturbance of
1
—
miction (?
micturition)
Vascular problems (n=1)
Aortal lesion (at
1
—
removal of
Not stated for subjective measures.
Other comments:
In particular, patients with an isolated
discopathy, who had not had previous
back surgery and/or pathology at the
same or another level benefited the
most from surgery.
“From our first and only patient with
revision of the prosthesis in this
series we learned about its difficulties
and dangers.”
It was noted the study included a
learning curve for technique, criteria
and patients selection.
40
Re-operation rate:
Type of re-operation
No
Re-operation at segment with prosthesis
(n=6)
Dorsal release
4
+ ligamentoplasty (Graf)
(1)
arthrodesis of facet
(1)
joints
Lateral decompression +
(1)
block of facet joints
+ facetectomy
(1)
Dorsal fusion*
2
At other levels (n=11)
Percutaneous nucleotomy
2
Disc prosthesis
7
Discectomy
1
Dorsal release
1
Related to complications (n=3)
Release of haematoma
2
Unsuccessful effort to
1a
reposition prosthesis
Fusion
1a
Vascular surgery (aorta)
3a
*: after partial removal of facet joint, with prosthesis in
situ; a: same patient
Table adapted from (Zeegers et al. 1999)
Only 25% (3/12) benefited from reoperation.
prosthesis)
General complications (n=5)
Infection of
4
—
urinary tract
Impotence,
1
—
retrograde
ejaculation
Deep venous
1
—
thrombosis
Prosthesis (n=2)
Malposition
1
1
Table adapted from (Zeegers et al. 1999) Note
percentages were not given.
Disc migration:
No migration (>2mm) noted at 2 years in any
of the prostheses.
Disc space height:
14% of all levels with a prosthesis showed a
decrease in height (> 25%) 2 years after
surgery. (disc space height quotient of Farfan)
No statistically significant difference in outcomes with
regard to the following factors:
•
Prosthesis positioning
•
Uni vs Bi vs Tri Replacement
•
Pure vs post discectomy discopathy
•
Preoperative duration of low back pain
•
Good vs a fair technical result
41
Study details
Key safety findings
Appraisal/Comments
Relative gain:
Gain
>70 (good)
60-70 (fair)
<60 (poor)
Complications:
Complication
No
Vascular problems
4.8% (5/105)
Temporary
1.9% (2/105)
neurological
deficits
Attributable to
2.9% (3/105)
technique
Bone
3.8% (4/105)a
complications
Total
10% (11/105)
a: n=1 endplate fracture- revised to fusion
n=1 lower endplate subsidence due to
osteoporotic bone
n=2 periprosthetic ossifications
Potential for bias:
Most results are reported for the entire
group which contains uni, bi and
trisegmental replacement patients. It may
have been more valid to group the results
by the number of segments replaced (ie
uni, bi and tri groups). It was not stated if
the patients were consecutive or not.
Case series
LeMaire9 1997, FRANCE
105 patients (154 prostheses
implanted)
Segment
No
L3/L4
6
L4/L5
72
L5/S1
76
Prostheses per patient
No
No
prostheses patients
1
58
2
46
3
1
Follow-up: Mean 51 months
Raynham, MA, USA)
Selection criteria:
50/105 (48%) had undergone 1 or
more surgical procedures before
the implantation.
Time
3 months
1 year
Final
Work status:
Work status
% patients
79%
5.8%
15.2%
Average relative gain
48.3%
72.8%
82.2%
Sedentary
workers
81%
17%
Light
workers
44%
35%
Heavy
workers
45%
26%
2%
21%
27%
Same work
Change of
work
unemployed
Total:
Work status
Same work
Change of work
unemployed
Total
60%
27%
13%
Improvement in radicular pain:
96.6 % of patients at 3 months
Improvement in back pain:
90.5% of patients at 3 months
Prosthesis mobility in degrees:
Flexion
Extension
L4/L5
L5/S1
9.65
6
3.4
3.5
Implant migration (%):
Total L4/L5 L5/S1
Anteriorly
33
44
23.5
Centred
56.4
53.7
41.1
Posterior
10.6
2.3
17.6
Note: prosthesis position was measured
as the difference between the centre of the
prosthesis and the centre of the
intervertebral disc (mm). Measurements
≥ 2mm were considered significant.
There was a significant correlation
between posterior joint pain and anterior
positioning of ≥ 4mm.
Modified Stauffer-Coventry Rating scale
used to measure ‘return to work’ and
‘quality of work’ outcomes. Details of this
scale were given.
Relative gain was calculated as = absolute
gain/maximal gain minus preoperative
score. Results considered good when
relative gain was >70%; fair or satisfactory
results were 60-70% gain and <60% was
considered poor.
Other comments:
It was stated “Bad results were attributed to
either incorrect indication (osteoporosis,
posterior osteoarthritis, overlying
thoracolumbar kyphosis), secondary
progression of a posterior facet joint
syndrome, or nonreturn to work, although
the relative gain was equal to or great than
70%”.
Lateral
bending
4
3.2
42
Re-operation:
1/105 (1%) because of an endplate fracture, surgery
revised to fusion.
Ross et al. 1997, UK
46 patients.
Follow-up: mean 3 years (range
11-72 months)
Oswestry Disability score:
Improvement from 52.2 to 33.4 (p=0.001)
Revision rate:
2/46 (4.3%)
None stated.
Potential for Bias:
Four patients (9%) either lost to follow-up
or had incomplete follow-up data sets. It
was not stated if the patients were
consecutive or not.
Raynham, MA, USA)
Oswestry Disability Score – validated
measure Postal Questionnaire .
Selection criteria:
Patients deemed suitable for disc
replacement using the Oswestry
Disability Scoring Instrument
Other comments:
43
Study details
Case series
Cinotti et al.11 1996, ITALY
46 patients. (36 unisegmental patients
and 10 bisegmental patients)
Follow-up: minimum 2 years (mean 3.2
years, range 2-5 years)
Segment
L5/S1
L4/L5
L3/L4
L4/L5 and L5/S1
L3/L4 and L4/L5
No
20
14
2
8
2
Selection criteria:
Patients were all operated on by the same
surgeon. Patients had disc degeneration
(n=22) or failed disc excision (n=24).
Patients had MRI or CR scans showing a
degenerated disc at one or two levels and
a painful discography at the same levels.
Exclusions: degenerative changes of the
facet joints (as seen on CT or MRI
scans), disc degeneration adjacent to a
fused area and spondylolisthesis.
Key safety findings
Appraisal/Comments
Clinical Results:
Result
No
Excellent
24% (11/46)
Good
39% (18/46)
Fair
30% (14/46)
Poor
7% (3/46)
(using guidelines previously reported)
Complications:
Complication
No
Disc migration
1/46 (2%)
Perianular
7/46a (15%)
ossification
Undersized prosthesis
4/46b (9%)
Subsidence on
9/46 (20%)
radiograph (without
failure of prosthesis)
Structural failures
0/46 (0%)
(on radiograph)
a: 3 patients had a malposition of the
prosthesis in the sagittal plane; 4 patients
developed spontaneous interbody fusion at
the operated levels.
b: implant collapsed into vertebral bodies
Potential for bias:
External assessor used for outcome
measures of clinical results and
success rate which should decrease
bias. A single surgeon performed
all procedures, negating any intersurgeon variability. It was not
stated if patients were consecutive
or not.
Re-operation (fusion):
Time
No
Soon after surgery
1/46 (2%)
2-4 years
7/46 (15%)
Total
8/46 (17%)
(8/17 patients with unsatisfactory results)
Success Rate:
69% unisegmental
40% bisegmental
(p=0.004)
77% (17/22) no previous back surgery
50% (12/24) previous back surgery (p=0.04)
Vertebral motion:
L5/S1
Operated level
L4/L5
9o (range 0-15 o)
16 o (range 10-21 o)
(p=0.003)
Disc prosthesis proportion
of the length of the endplate
in the sagittal plane
>80% (range 80-89%)
(n=28)
60-76% (n=18)
Average vertebral
motion at the
operated level
12 o
It was stated ‘subsidence of the implants
into the vertebral bodies and perianular
ossifications did not affect the clinical
outcome’.
Outcome measures and their
validity:
Well defined definitions of
outcomes which had been used in
previous publications.
Steps taken to optimise the
accuracy of ROM measurements
also reported.
Other comments:
Authors concluded that poor patient
selection rather than prosthesis
limitations was the primary cause of
the failure.
Authors also noted that the SB
Charité III device does not appear
to be suitable for implantation at
two contiguous levels (unless an
undersized prosthesis is placed at
the second level or the second
device is positioned more anteriorly
to provide adequate disc space at
both implanted levels).
6o (p=0.01)
44
Placement
Centrally/posteriorly
Anterior
Postoperative care
Exercise 1 week
postoperatively
Corset for 3 months
Vertebral motion
(o)
12
5
Range of motion
11o
6 o (p<0.05)
No degenerative changes were found at the levels
adjacent to the disc replacement in 10 patients who had
MRI at follow-up.
Postoperative use of analgesics:
Frequency
No
Occasional
9% (4/46)
Continuous
26% (12/46)
Resumption of work:
Level
No
Same level
67% (31/46)
Lower level
20% (9/46)
Cannot work
9% (4/46)
Unemployed
4.3% (2/46)
45
Study details
Key safety findings
Appraisal/Comments
Case series
Griffith et al. 1994, USA, GERMANY,
FRANCE, NETHERLANDS
Pain relief:
Significant number of patients experienced pain
relief both in leg and back pain. (p<0.05)
International multi-centre study with
retrospective chart review.
Leg Pain:
93 patients (139 implants)
Segment
No
L3/L4
15
L4/L5
66
L5/L6
2
L5/S1
55
L6/S1
1
Single prosthesis in 53%, two prostheses in
45% and three prostheses in 2%.
Follow-up: mean 11.9 (SD 8.3) months
(range 1-37 months).
A total of 3.2% (3/93) patients were lost to
follow-up.
Selection criteria:
Patients from three European surgeons
experienced in the implantation of the disc
prosthesis participated in the study.
Patients had L3-L4, L4-L5, L5-L6, L6-S1
replacements. They had degenerative disc
disease, postnucleotomy syndrome,
internal disc derangement, failed fusion,
instability, or herniated nucleus pulposus.
Patients with previous lumbar surgery were
included.
% reduction
Right leg
48% (p<0.05)
Left leg
41% (p<0.05)
Straight
50%
leg raising
(p<0.01)
test
Significant improvement was found in terms of
pain intensity compared to preoperative pain
scores (p< 0.001). Surgeon A did not report
analog pain scale scores.
Self-reported walking distance:
(%)
Improved
39%
Decreased
2%
Same
58%
Data unavailable from Surgeon A.
Neurological weakness:
81% reduction in patients with weakness
(p<0.01).
43% (3/7) with no preoperative back
pain developed postoperative back pain
Implant failure:
1% (1/93) minor core failure; a
deformation of the metal ring
surrounding the polyethylene core.
Problems related to prosthetic choice:
Implant migration: 5/93(4.3%)
Implant dislocation: 1/93 (1% )
Not related to
device
Equivocal
(not able to
decide if related
to device)
No
30/93 (32%)
(phlebitis/leg
thrombosis n=2;
injured vein
n=16)
16/93 (17%)
Potential for bias:
Losses to follow-up of three patients (3.2%)
Unclear what measures were taken to
standardise surgery and outcomes
measurement at the various sites (for
instance, one surgeon did not use the
specified analogue pain scale)
No detail given of whether the groups from
each centre had similar characteristics.
With retrospective chart review, some data
may be inadvertently different or missing
altogether and follow-up may be
inconsistent.
Ten point analogue pain scale used.
Other comments:
Many complications noted but obvious care
taken to document all complications which
could possibly explain the seemingly high
rates.
The summary and analysis of data was
performed by an independent research
organization with no corporate affiliation to
the manufacturer of the device or surgical
investigators.
Return to work status:
Patients unable
to work
Preoperatively
40/92 (44%)
Postoperatively
37/89 (42%)
p=0.83
Results for work status varied between the
surgeons.
46
Re-operation rates:
3/93 (3% )
(revised to percutaneous nucleotomy,
foraminoplasty and A-P spinal fusion
respectively).
Study details
Case series
David et al.13 1993, FRANCE
22 patients
Follow-up: minimum 1 year
Selection criteria:
Cases included where fusion in situ is to be
avoided (DDD with collapsed disc, failed
backs and instability at a maximum of two
levels)
Key safety findings
Appraisal/Comments
65% of patients had ‘good to excellent’ results.
No loosening of the prosthesis or osteolysis at
the bone-prosthesis interface has been noticed
in patients with two or more years follow-up.
Not stated
Potential for bias:
The method of patient selection was not
detailed, and it was not stated if patients were
consecutive or not.
Segmental mobility remains on dynamic
radiograph.
No validated measures were used, outcomes
appeared to be subjective.
Other comments:
Author noted that disc replacement surgery is
still ‘far from being routine’.
47
ProDisc II
Study details
Randomised Controlled Trial
Delamarter et al. 2003, USA
VAS:
Part of a multicentre prospective RCT (FDA IDE
study).
Artificial disc replacement (ProDisc): n=35
Fusion: n=18
1-level surgery
ProDisc Fusion
L3/L4
n=0
n=1
L4/L5
n=9
n=4
L5/S1
n=10
n=3
2-level surgery
ProDisc Fusion
L3/L5
n=1
n=0
L4/S1
n=14
n=10
Note: there is a mistake in the table as there should
be 16 patients who had 2-level surgery in the
ProDisc group.
Follow-up: minimum 6 months (6 to 15 months).
Clinic visits at 6 weeks, and 3, 6 and 12 months.
Implant: ProDisc II (Spine Solutions)
Comparison: Artificial disc replacement versus
circumferential fusion (standard of care).
Selection criteria: Inclusion criteria: age between
18 and 60 years, failed conservative treatment for
at least 6 months; minimum Oswestry score of
40/100; and no more than one- or two- level
degenerative disc disease from L3 to S1.
Exclusions: patients with metal allergies, previous
lumbar fusions, compromised vertebral bodies,
ProDisc
Fusion
Preoperative
7.44
6.84
6 weeks
2.89a
4.74†
3 months
3.65
4.78‡
6 months
4.38
3.96 a
a: p<0.05 versus preoperative; †: p<0.01; ‡: p<0.001
Oswestry:
Preoperative
6 weeks
3 months
6 months
*: p<0.05
ProDisc
31.26
20.65
17.93
15.07
Fusion
30.67
25.00
25.00*
14.57
Range of Motion:
ProDisc
Mean [SD]
range
(degrees)
Patients treated at L4/L5
Movement at L3/L4
Preoperative
5.48[5.31]
-7.00-22.00
6 weeks
5.90[4.59]
-1-17.00
3 months
2.55[6.20]
-11.00-12.00
6 months
6.89[3.26]
3-13
Movement at L4/L5
Preoperative
7.04[5.60]
Fusion
Mean[SD]
range
(degrees)
5.00[2.89]
1.00-9.00
7.50[2.12]
6.00-9.00
Key safety findings
Appraisal/Comments
Implant failure:
There were no incidents of
implant migration, breakage,
or mechanical failure after
disc replacement.
Potential for Bias:
Randomisation was weighted 1:2 to
receive either fusion or the artificial
disc.
All patients were blinded to the
treatment until after the surgery.
The average age, gender, narcotic
use, smoking history, and worker’s
compensation percentage were not
statistically significant between the
groups.
The ADR group had a greater
percentage of patients with pain >1
year than the fusion patients (100%
vs 89%, p<0.04).
The fusion group was smaller which
may have influenced statistical
significance in that group.
Analysis limited to one site with
relatively short follow-up time.
Outcome measurements were all well
validated. The consistency of
measurement of radiographic angular
measurements was assessed by
evaluating the untreated L3-L4
intervertebral segments- there were
no significant differences before
surgery and at 6 months and between
groups.
Other comments:
11.46[7.86]
48
and severe facet degeneration.
-5.00-18.00
7.62[4.21]
-5.00-15.00
3 months
7.55[4.15]
-1.00-17.00
6 months
10.11[3.33]
5.00-17.00
Patients treated at L5/S1
Movement at L3/L4
Preoperative
5.75[5.93]
-7-22.00
6 weeks
4.88[3.97]
-6.00-13.00
3 months
4.06[5.95]
-11.00-10.00
6 months
6.23[1.06]
5.00-8.00
Motion at L5/S1
Preoperative
6.17[8.19]
-25.50-16.00
6 weeks
5.42[5.80]
-10.0-13.00
3 months
8.67[6.46]
1.00-24.00
6 months
7.62[4.43]
2-17.00
0.00-27.00
6 weeks
0.00[4.24]
-3.00-3.00
4.75[3.96]
-4.0-9.00
7.50[2.38]
6.00-12
3.33[8.23]
-10.0-21
4.75[4.19]
2-11
49
Study details
Key safety findings
Operative time:
Significantly reduced in the ProDisc versus
fusion patients.
It was not reported whether or not
any complications occurred.
Appraisal/Comments
Randomised Controlled Trial
Zigler 2003 USA
39 patients
Comparisons:
Artificial disc replacement (ProDisc): 28
Fusion: 11
Two-level surgery
ProDisc
Fusion
5/28 (18%)
1/11 (9%)
(3 ProDisc cases were nonrandomized ‘teaching’ cases at
the beginning of the study).
Follow-up: 6 months, data collected at 6 weeks, 3 and 6
months postoperatively.
Implant: ProDisc II
Selection criteria: age between 18 and 60 years; at least 6
months failed nonoperative therapy; degenerative disc
disease at ½ adjacent vertebral levels between L3 and S1;
Oswestry score at least 40%; psychosocially, mentally or
physically able to comply with the protocol, including
adhering to follow-up and filling out form.
Exclusions: >2 degenerative levels; endplate dimensions
<34.5mm in coronal plane and/or <27mm in sagittal plane;
known allergy to titanium, polyethylene, cobalt, chromium
or molybdenum; prior lumbar fusion; posttraumatic
vertebral body compromise/deformity; facet joint
degeneration; lytic spondylolisthesis or spinal stenosis;
degenerative spondylolisthesis of grade >1; back/leg pain
of unknown aetiology; osteoporosis; metabolic bone
disease; morbid obesity; pregnant or interested in
Hospital stay:
Shorter in the ProDisc versus fusion patients
(2.1 versus 3.5 days).
Postoperative rehabilitation:
More rapid after ProDisc versus fusion, with
ProDisc patients having significant
improvements in range of motion compared to
preoperative values, and better motion than the
fusion patients. Fusion patients had slower
recovery to independent ambulation and slower
return to recreational activities.
Return to work:
ProDisc
Fusion
8 weeks
16 weeks
Oswestry scores:
In the ProDisc group, Oswestry scores steadily
decreased after surgery, while they increased in
the fusion group at 3 months (possibly the
result of postoperative immobilisation).
Potential for bias:
Groups were similar in demographics,
including gender, age, weight, smoking
history, preoperative medication usage,
nonoperative treatment and prior
surgeries.
Ten patients had single level disc
replacement before the two-level arm of
the study began.
This was a small group size of a larger
study, with short follow-up. It
comprised the first 39 patients with at
least 6 months follow-up.
The fusion is expected to appear worse
at shorter follow-up times than disc
replacement, but this gap may be
reduced at longer follow-up.
Outcome measurements and their
validity:
This study was presented in more of a
descriptive than quantitative way, with
little quantitative objective data with
which to compare the groups.
Other comments:
VAS scores:
Decreased in both groups, more so in the
ProDisc patients, but this was not statistically
significant.
Satisfaction scores:
Declined sharply in the fusion group at 6
50
becoming pregnant in next 3 years; active systemic/local
infection; medications or drugs known to potentially
interfere with bone/soft tissue healing, excluding smoking;
rheumatoid arthritis or other autoimmune
spondylarthropathies; systemic disease including AIDS,
HIV, hepatitis; active malignancy.
months, trending towards significance.
51
Study details
Key safety findings
Appraisal/Comments
Bertagnoli et al. (2005) Germany
Clinical Outcomes
Device related complications
Potential for bias
104 patients were selected for follow-up
Preoperative Oswestry disability scores decreased from
53% to 29% at 24 months follow-up.
There were no cases of
loosening, subsidence,
migration, metallic or
polyethylene failure, allergic
reaction/rejection, visceral or
neurologic injuries caused by
the implant components,
and/or infection.
Only patients who completed the
24 month follow-up period were
included in this study (104 of a
possible 118 patients fulfilled the
follow-up criteria).
Case series
Single level DDD
Follow-up: Pateints were assessed at 3, 6, 12 and 24
months post-surgery
Implant: ProDisc II
Inclusion criteria
Prospective data was compiled for single-level Prodisc
procedures from March 2000 to December 2001. Patients
aged 18 to 60 years were enrolled. All patients had
disabling discogenic low back pain with or without
radicular symptoms resulting from DDD from L3 to S1 as
comfirmed bymagnetic resonance imaging, computed
tomography and, when indicated, discography.
Exclusion criteria
Patients with spinal stenosis, osteoporosis, prior fusion
surgery, chronic infections, metal allergies, pregnancy,
facet arthrosis, inadequate vertebral end-plate size, more
than one level of spondylosis, neuromuscular disease, ,
pregnancy, Worker’ Compensation, spinal litigation, BMI
>35, and/or any isthimic or degenerative spondylolisthesis
greater than Grade I.
The decrease in Oswestry disability scores occurred
primarily in the first 3 months post-surgery (Repeated
measures GLM analysis: F(1,103) = 132.80, p<0.001, ŋ2 =
0.56) and was sustained for 24 months (F(1,103) = 113.71,
ŋ2 = 0.53). No significant changes were observed from 3
months to 24 months follow-up.
VAS decreased from 7.6 to 3 at 24 months. Significant
change was noted in the first 3 month post-surgery
(F(1,103) = 222.64, p<0.001, ŋ2 = 0.68). This was
sustained until the 24 month follow-up (F(1,103) =
161.361, ŋ2 = 0.61, p<0.001.
Patient Satisfaction (%)
3
59.2
Months
6
12
57.8
55.4
24
58.3
Satisfied
34.0
27.4
32.8
38.5
Unsatisfied
4.8
14.7
11.9
3.1
Completely
satisfied
Approach related
complications
validity:
Outcome measurements were
generally well validated.
Other comments:
Two cases of retro peritoneal
hematomas and a single
subcutaneous hematoma was
diagnosed during the
perioperative period.
One case of retrograde
ejaculation which recovered
spontaneously at 6.5 months
post-surgery.
One case of persistent leg
pain after complication of an
L5-S1 implant which required
posterior exploration and
decompression. Posterior
subarticular stenosis was
identified and the patient
continues to be unsatisfied
with her outcome at 32
months post index procedure.
52
Back Pain (%)
No pain
Occasional
pain
Regular
pain
Preop
0
15.3
3
21.3
67.0
84.6
11.6
Months
6
12
22.8 28.7
62.4 59.4
14.8
24
32.0
59.2
11.9
9.0
Months
6
12
60.4 45.2
28.6 41.6
24
62.6
29.5
Radicular Pain (%)
No pain
Occasional
pain
Regular
pain
Preop
11.9
45.5
3
53.6
36.1
42.6
10.3
11.0
13.2
8.8
Medication usage
Medication (nonsteroidal anti-inflammatories, narcotics and
morphine derivatives) usage decreased significantly
compared to pre-operative usage rates.
Radiographic Analysis
Median preoperative height of affected discs was 4mm presurgery, after surgery disc heights were increased to a
median of 13mm (p<0.001).
Motion of affected discs increased from 3º before surgery
to 7º after surgery (p<0.004).
Height of adjacent level discs did not change significantly
post-surgery.
53
Study details
Key safety findings
Appraisal/Comments
Early postoperative complications:
none
Potential for bias:
The study included only two patients
with complications and did not mention
the total number of patients who had
the operation, meaning the rate of
artificial disc dislocation is unknown.
Case series
Aunoble et al. 2004, FRANCE
n=2
L5-S1: n=2
Follow-up: ~4 -20 months
Implant: ProDisc II
Selection criteria: Not stated
Oswestry score:
Improvement of 60% up to 4 months
postoperatively in 1 patient; and from 44 to
10% in the other patient.
Re-operation:
A fusion was performed in both patients.
Dislocation of disc: n=2
In patient 1, after 4 months the
patient began to experience severe
acute low back pain, x-ray showed
an anterior dislocation of the
polyethylene.
In patient 2, 1 month
postoperatively severe pain was
experienced with radiographs
showing L5-S1 listhesis (grade 1)
and evidence of polyethylene inlay
dislocation. The patient became free
of pain again until 19 months after
surgery when the back pain
worsened (Oswestry score 24%)
and because of a risk of metallosis
in relation with micromotion, a
fusion was performed.
validity:
The Oswestry score is well validated.
Other comments:
54
Study details
Case series
Tropiano et al. 2003, FRANCE
n=53
December 1999 to December 2001
evaluation of patients who had previous
lumbar disc replacements.
11/53 (21%) had one prior surgery; 9/53
(17%) had two or more prior surgeries; 33/53
(62%) had no prior surgery.
Segment
No
L5/S1
27
L4/L5
13
L4/L5 and L5/S1
9
L3/L4 and L4/L5
2
L3/l4, L4/L5 and
2
L5/S1
Follow-up: Mean 1.4 years (1 to 2 years)
Implant: ProDisc II
Selection criteria: Disc degeneration (n=33),
failed spine surgery (n=20). All patients had
at least 6 months of severe back pain and had
failed non-surgical treatment.
Exclusions: Known chronic disease of major
organ system; history of local infection;
pregnancy; associated facet degeneration;
history of abdominal or retroperitoneal
surgery near planned anterior approach;
osteoporosis or osteopenia; structural spinal
deformities; absence (postoperative) of
posterior elements (eg. after laminectomy
and facetectomy).
Key safety findings
Appraisal/Comments
Surgery times and hospital stay:
Time
Operative time
Mean 104 min
(range 32-250 min)
Hospital stay
Mean 9 days
(range 4-31 days)
Total Complications:
5/53 (9%)
Potential for bias:
The clinical evaluation and
questionnaire administration were
performed by individuals not directly
involved in patient selection, surgery,
or postoperative care, reducing the
potential for bias. It was not stated if
the patients were consecutive or not.
One surgeon performed all
procedures, minimising inter-surgeon
variability.
Patient satisfaction:
Satisfaction
No
Entirely satisfied
46/53 (87%)
Satisfied
7/53 (13%)
Not satisfied
0/53 (0%)
32/33 (97%) of patients with no previous surgery reported
satisfactory results and 10/11 (90%) of those with previous
lumbar surgery reported satisfactory results.
Resumption of work and activities of daily living:
Function
No
Full
38/53 (72%)
Slightly limited
15/53 (28%)
VAS lumbar:
Preoperative
3 months
6 months
Mean 1.4 years
*: p<0.05
VAS
Mean[SD]
7.4[2.5]
1.8[ 2.1]*
1.4[ 2.2]*
1.3[ 1.8]*
Vertebral body fracture:
1/53 (2%)
Implant malposition:
2/53 (4%)
Persistent radicular pain:
2/53 (4%) (no radiographic
evidence of neural compression;
resolved after 3 and 5 months)
Mechanical failure/loosening:
No radiolucent or sclerotic lines
were noted in reponse to the
implant; there were no
periannular ossifications and no
mechanical implant failures. No
degenerative changes were seen
at the levels adjacent to the disc
replacement or at the facet
joints.
validity:
Valid outcome measures were used.
Other comments: Clinical results of
patients with single or multilevel
surgery were equivalent and results
were good in patients with previous
lumbar surgery.
The vertebral fracture occurred in a
woman with unrecognised
osteopenia.
There was an increase in lordosis,
related to the lordotic shape of the
implant.
Complications were not related to the
device, but to errors in judgement
and technique by the surgeon, or
from the anterior approach.
Authors believe the primary
indication for ProDisc II implantation
is in patients with single- or
multilevel lumbar discopathy with
55
VAS radicular:
Preoperative
3 months
6 months
Mean 1.4 years
*: p<0.05
VAS
Mean[SD]
6.7[ 3.0]
2.8[3.2]*
1.6[ 2.8]*
1.9[ 2.6]*
Oswestry:
Preoperative
3 months
6 months
Mean 1.4 years
*: p<0.05
Mean[SD]
56[ 8.2]
30[ 10.1]*
18[ 9.9]*
14[7.4]*
disc collapse and intersegmental
hypermobile instability without
significant posterior changes,
between 18 and 60 years of age.
Secondary indications include
patients with lateral recess stenosis
due to disc degeneration and loss of
disc space height, patients with
single- or multilevel postdiscectomy
syndrome or failed back surgery
syndrome, and patients with
discopathy adjacent to a fusion.
These secondary indications need a
larger patient cohort for
confirmation.
Comparison of patients with 1-level or multilevel disc
replacement:
1-level
Multilevel
(n=40)
(n=13)
Mean[SD] Mean[SD]
VAS lumbar
7.4[ 2.3]
7.4[ 3.4]
preoperative
VAS lumbar last
1.3[ 1.7]
1.3[ 2.1]
follow-up
VAS radicular
6.5[ 3.1]
7.4[ 2.5]
preoperative
VAS radicular last
2.2[ 2.8]
1.2[ 1.9]
follow-up
Oswestry
27[ 8.4]
31[ 7.1]
preoperative
Oswestry last follow- 8[ 8.1]
5[ 4.7]
up
56
Radiographic findings:
Flexion-extension after surgery
L5-S1
L4-L5
(degrees)
(degrees)
10
Range of
8
range 2-12
range 8-18
motion
Mean lumbar lordosis:
Before surgery
Final follow-up
56.7 o
range 30-72 o
61.9 o
range 46-72 o
Reoperation:
3/53 (6%) (1 case of vertebral body fracture and 2 cases of
malposition)
57
Study details
Key safety findings
Appraisal/Comments
Case series
Bertagnoli & Kumar 2002, GERMANY
Clinical outcome:
Postoperative complications:
1/108 (systemic septicaemia,
resolved with antibiotics)
Potential for bias:
Operations were performed by a
single surgeon, reducing variability
caused by different surgeons. It was
not stated if the patients were
consecutive or not.
n=108 (134 prosthetic discs)
Operations performed by a single surgeon.
Disc degeneration (vertical instability; n=67);
failed disc surgery syndrome (35); transition
zone syndrome (n=6).
Segment
No
L5/S1
61
L5/L6
3
L4/L5
31
L3/L4
7
L2/L3
3
L4/L5 and L5/S1
10
L2/L3 and L4/L5
1
L3/L4 and L4/L5 and
2
L5/S1
Note: not sure of denominator, numbers add
to 118.
Follow-up: 3 months to 2 years; 54 patients
for more than 1 year.
Implant: ProDisc II
Selection criteria: All patients had previously
been treated with conservative management
for a minimum of 6 months, and all had a
positive preoperative response to
discography.
Exclusions: Severe osteoporosis,
physiological dysfunction, history of
previous disc infection, severe posterior
element pathologies, fracture of the vertebra,
and tumours.
No
Excellent
98/108 (91%)
Good
8/108 (7%)
Fair
2a/108 (2%)
Poor
0/108 (0%)
a
: both patients had advanced disc degeneration also
involving the adjacent levels and secondary osteoarthrosis
of the facet joints.
Residual leg or back pain:
9/108 (8%)
Analgesic use:
> 2 weeks
6 months to
1 year
Occasionally
No
45
12
33
Resumption of duties of daily living:
Mean 2.3 weeks (range 1.5 to 3.2 weeks)
Ability to resume work (n=54, follow-up of >1 year):
No
At same level
35/54a (65%)
At lower level
17/54 (31%)
Not able to resume work
2/54 (4%)
a: patients with more than 1 year follow-up
Average range of vertebral motion:
Segment
Mean (range)
degrees
L5-S1
9 (2-13)
L4-L5
10 (9-13)
L3-L4
10 ( 8-15)
L2-L3
12 ( 9-15)
Implant loosening or
subsidence of prosthesis:
None
Structural disc failure:
None
validity:
Validated measures, such as VAS
and Oswestry scores, were not
performed. It was not stated what
constituted an excellent, good, fair or
poor clinical outcome.
Other comments:
All operations were performed using
less invasive techniques.
The following categories of
indications for surgery were stated:
Prime: single disc level; >4 mm
remaining disc height; no
osteoarthritic changes to facet joints;
no adjacent level degeneration; intact
posterior elements.
Good: single or double level; >4mm
remaining disc height; no primary
osteoarthritic changes to facet joints;
minimum degeneration of adjacent
discs; minimum posterior segment
instability.
Borderline: single, double or triple
level; <4mm remaining disc height;
primary osteoarthritic changes to
facet joints; minimum adjacent level
degeneration; minimum posterior
segment instability; adjacent to
58
Average range of vertebral motion at adjacent segments
compared to preoperative range:
No
Decreased range 5o
6/108 (6%)
Range 3-8o
Increased range 6o
86/108 (80%)
Range 3-8o
Unchanged
16a/108 (15%)
a
: 12 patients had presented with advanced degenerative
disc disease prior to surgery; 4 patients had secondary
changes of the facet joint in addition to advance
degenerative disc disease prior to surgery.
fusions.
Poor: single, double or triple level;
gross degeneration of the spine;
secondary osteoarthritic changes to
the facet joints; <4mm disc height at
the adjacent levels; posterior segment
instability.
Progression of disc degeneration at adjacent levels:
5/108 (5%; at L5-S1 in 3 and at L4-L5 in 2; all patients
presented with an anterior disc height of <7mm)
Outcome relative to indication for surgery:
% patients (range)
Prime
98 (96-99%)
Good
93 (89-97%)
Borderline
83 (79-88%)
59
Study details
Case series
Mayer et al. 2002, GERMANY
n=34 first consecutive patients
multicentre study
June 2000 to March 2002
Segment
L5/S1
L5/L6
L4/L5
L4/L5 and L5/S1
L2/L3
No
24
3
3
3
1
Follow-up: Mean 5.8 ± 3.0 (SD) months (26/34
patients reached follow-up, the others were <3
months postoperative.
Key safety findings
Appraisal/Comments
Operating time:
Mean 130.9[45.9] minutes
(range 88-300 minutes)
Blood loss:
117 ml per level (range 30-350 ml)
Potential for bias:
Patients were consecutive, reducing
the risk of selection bias.
Hospital stay:
Mean 12.0 days (range 4-25 days)
Patient satisfaction at last follow-up:
(%)
Completely satisfied
60.9
Satisfied
21.7
Not satisfieda
17.4
a: all the patients who were not satisfied said they
would undergo the operation again if they were
faced with the same choice.
VAS score:
Implant: ProDisc II
Selection criteria: Causes of disc degeneration
were: degenerative disc disease (21/34);
degenerative disc disease + disc herniation (4/34);
FBS or postoperative osteochondrosis (5/34);
adjacent level degeneration (3/34); degenerative
following nucleus replacement (1/34).
Preoperative
Reduction
after surgery
Mean VAS score
6.3
3.9, range 8.4 point
reduction to 7.5 point
increase
Oswestry score:
Preoperative
Reduction
after surgery
Mean[SD]
19.1[7.4]
range 1-32
11.5[9.6]
range 27 point reduction
to 12 point increase
Lower back pain:
None in 76% of patients at their last follow-up.
Loosening or migration of implant:
None
Subsidence of adjacent vertebrae:
None
Complications related to surgical
procedure:
3/34
Nerve root irritation:
1/34 (irritation of the L5 nerve root
several days postoperatively; CAT
scan showed an extra-foraminal
protrusion of nucleus material
compromising the L5 nerve root on
the left side. Neurological exam
was normal and a 3 week outpatient
course of conservative treatment
was successful)
Inlay dislocation:
1/34 (patient had an increase of pain
5 weeks after surgery with no
notable trauma; radiographs showed
an inlay dislocation anteriorly; it
was believed the polyethylene inlay
was not completely snapped into
the inferior endplate; a new implant
was successfully used).
Retrograde ejaculation: 1/34
validity:
Validated outcome measures were
used.
Other comments:
Surgery was performed using
minimally invasive techniques using
a mini-laparotomy.
The ‘medium’ ProDisc was used in
36/37 segments and ‘large’ was used
at one level.
The implant with 6o lordosis angle
was used in 65.4% of cases, the 11o
angle was used in 34.6% of cases.
The polyethylene inlay of 10 mm
height was used in 34 segments; the
12mm inlay in two segments; and the
14m inlay in one segment.
Postoperative fusion:
None
60
Acroflex Acromed
Study details
Key safety findings
Appraisal/Comments
67% (4/6) of patients had a satisfactory
result:
Result
No
Excellent
1
Good
2
Fair
1
Poor
2
Satisfactory level of bony ingrowth in all
prostheses.
Potential for bias:
Small sample size, it was not stated if the
Case series
Enker et al.14 1993, USA
6 patients
Follow-up: 3.4 years (range 3-4 years)
Implant: DePuy Acroflex Acromed (AcroMed
Corporation, Cleveland, OH, USA)
Selection criteria: Patients requiring single level
replacement only (disc degeneration in the
lumbosacral spine in five patients and isolated disc
resorption in one patient)
Four patients had had previous spinal surgery.
All patients had confirmatory discography.
Exclusions: Previous decompressive laminectomy,
osteopenia, facet joint arthritis, spinal stenosis,
disc hernation, pseudoarthrosis, arachnoiditis,
psychological dysfunction, abdominal wall
hernail, previous iliofemoral phlebitis, prior
retroperitoneal radiation and history of discitis or
vertebral osteomyelitis.
Lateral flexion/extension:
Average 8o (range 2-16 o)
Anterior translation:
Average of 2.3 mm (range 0-4 mm)
Reoperation rate:
1/6 (17%) due to implant failure- a
fracture through the rubber core of the
implant evident on radiograph.
Radiographic changes:
Annular ossification occurred in two
patients, one of whom had autofusion,
the second still had angular motion on
lateral flexion/extension radiographs.
There were no cases of vertebral endplate
erosions, sclerosis, or vertebral body
remodeling, component end plate
debeading, adjacent-level disc
degeneration or local or systemic
complications.
What constitutes an excellent, good or fair
clinical outcome was carefully detailed (but
not a validated scale).
Other comments:
After publication of this article, the Acromed
device was re-designed so that only a single
piece of rubber was used as the inner core
component.
61
Study details
Key safety findings
Appraisal/Comments
Operating time:
Mean 135 minutes
Blood loss:
Mean 140 ml
Potential for bias:
It was not stated if the patients were
consecutive or a selected group.
Hospital stay:
Mean 6.3 days
Operative complications:
None
Clinical results at 1 year:
Displacement of implant:
Early partial displacement in one
case.
Other comments:
The purpose of the study was to “evaluate the
design of a titanium/polyolefin artificial disc,
refine the surgical technique, assess safety
and measure outcome to determine if an RCT
is justified.”
Cine-fluoroscopy was superior in
demonstrating vertebral motion compared to
standing lateral flexion/extension
radiographs.
“Although a satisfactory clinical outcome was
obtained, technical difficulties with insertion,
the case of partial implant displacement and
radiological evidence of suboptimal endplate
contact have led to refinement of the titanium
endplates.”
Case series
Freeman et al.14 2001, AUSTRALIA (abstract)
11 patients
Follow-up: 2 years (n=3) and 12 months (n=8)
Clinical assessment carried out preoperatively and
at 6 and 12 weeks, 6 months and 1 and 2 years.
Surgery since April 1998
L5/S1
n=10
Implant: AcroFlex
Selection criteria: All patients entering the pilot
study had single level disc disruption at L4/L5 or
L5/S1 with disabling lower back pain of at least
12 months duration. Diagnoses were confirmed by
discography and an independent assessment
included physical examination, visual analogue
scales (VAS) for pain, Low Back Outcome Score
(LBOS), Oswestry Disability index (ODI), SF-36,
lateral flexion-extension radiographs and MRI.
VAS
ODI
LBOS
SF-36
Average improvement
39%
12 pt
14 pt
Improvement in 5/8
sub/scales
Vertebral motion:
In 10 patients satisfactory movement of
the vertebral motion segment was shown
by cine-fluoroscopy.
Heterotopic calcification:
One late case.
62
Study details
Key safety findings
Oswestry score:
Time
Score
6 months
82%
1 year
86%a
a this exceeded the acceptance criteria
of the study of 75%
Disc subsidence at 1 year:
None (based on detection threshold of
2mm)
Appraisal/Comments
Case series
Le Huec et al.2003, FRANCE (abstract)
n=30
L4/L5 or L5/S1
Follow-up: 1 year
Implant: Maverick lumbar Disc Prosthesis
(Medtronic, USA)
Selection criteria: Patients requiring a single level
implant with symptomatic low back pain resistant
to conservative treatment for more than 1 year.
VAS:
Time
Preoperative
Postoperative
Mean[SD]
7.1[2]
2.7[1.8]
Range of motion:
Mean 6 ± 4o (range 3-12o)
Device migration:
No evidence of anterior and/or posterior
migration.
Spondylotic bridging of implant disc
space:
No evidence.
Removal or revision of prosthesis:
None
Potential for bias:
The range of motion was determined by an
independent radiologist.
The follow-up was too short to assess longer
term outcomes.
It was not stated whether or not the patients
were consecutive.
Other comments:
The study was in abstract form only, limiting
the available outcome data.
Non-device complications:
1/30 (3%, injury to ureter)
63

Artificial Lumbar Disc Replacement

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