Heterotopic Ossification in Total Cervical ADR

[Harrison]

Folks,

An informed member was kind enough to share some recent information on ProDisc cervical and heterotopic ossification (autofusion).

I am quite puzzled by this and would have liked to have had the “story behind the numbers” before posting. However, I urge you all to NOT jump to any conclusions about the efficacy of the ProDisc C (or any other cervical discs) until more contextual information can be found on this issue. As you seasoned folks know, ProDisc C patients on this forum have done quite well.

Related topics from this board on HO here.
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Heterotopic Ossification in Total Cervical Artificial Disc Replacement.

Spine. 31(24):2802-2806, November 15, 2006.
Mehren, Christoph MD *; Suchomel, Petr MD, PhD +; Grochulla, Frank MD *; Barsa, Pavel MD +; Sourkova, Petra MD +; Hradil, Jan MD +; Korge, Andreas MD *; Mayer, H Michael MD, PhD *

Abstract:
Study Design. Prospective clinical study enrolled in 2 centers (Munich and Liberec) as part of a prospective European multicenter study with ProDisc C (Synthes Inc., Paoli, PA).
Objectives. The first goal of the study was to evaluate the rate of heterotopic ossifications identified with plain radiograph following total cervical disc replacement (TCDR). The second goal was to show whether segmental motion can be preserved, and whether TCDR can provide improvement of the patient's ability to perform activities of daily living as well as a decrease of pain.

Summary of Background Data. Only a few reports about the radiologic outcome after TCDR are published so far. Heterotopic ossification is a well-known phenomenon after total hip arthroplasty. The rate of heterotopic ossification following TCDR is unclear.

Methods. The radiographs of 54 patients (in total, 77 implanted prostheses) were analyzed 1 year after TCDR with a ProDisc C prosthesis. We classified the heterotopic ossification in 5 grades according to a recently published classification system for lumbar total disc replacement. For clinical parameters, the visual analog scale and the Neck Disability Index were evaluated preoperatively and 1 year postoperatively. The Student t test and Wilcoxon test were used for statistical analysis.

Results. In 26 treated segments (33.8%), no heterotopic ossification was detectable. Grade 1 ossifications were present in 6 levels (7.8%). A total of 30 segments (39.0%) showed grade 2 ossifications. Heterotopic ossifications that led to restrictions of the range of motion were present in 8 cases (10.4%). One year postoperatively, 7 cases (9.1%) had a spontaneous fusion of the treated segment. The clinical parameters improved significantly and were similar to previous reports about TCDR.

Conclusions. Only 33.8% of the patients did not show any signs of heterotopic ossification, and the rate of spontaneous fusion after TCDR 1 year after surgery was unexpectedly high. There were 49.4% of the patients with grade 2-3 ossification, which lets us suspect an even higher rate of spontaneous fusion after long-term follow-ups. Motion preservation after TCDR is only guaranteed if spontaneous fusion can be prevented. Thus, mobility of the implanted segments needs to be further studied.

[chasswen]

wouldnt this make one believe it applys to all cevical discs?
prehaps in the neck the space is smaller and with that the bone growing coating promotes bone growth.
just food for thought.
chuck

[sahuaro]

This is indeed troubling. Harrison: Is there a way of PM'ing the small sample of cervical ADR recipients here to get a survey of their experiences? (I am suggesting the PM route because those who are doing well may not be checking into the site)

[tmont]

Check this out, folks...a year old but worth the read:

Article Outline
Abstract
The Genesis of Arthroplasty
Patient Selection
Prestige Cervical Disc
History
Prestige I
Prestige II
Prestige ST
Implantation of the Prestige ST Cervical Disc
Outcomes for Prestige I Cervical Disc
Outcomes for Prestige II Cervical Disc
Prestige LP
Bryan Cervical Disc
History
Description
Implantation
Outcomes
Bryan Accel Cervical Disc
Pro-Disc-C Cervical Disc
History
Description
Implantation
Outcomes
Complications of Cervical Arthroplasty
Explant Analysis
Heterotopic Ossification

"Early in the experience with large joint arthroplasties, the development of heterotopic ossification was noted. This exuberant periprosthetic bone formation can bridge across a joint and render it immobile, thus defeating the purpose of the motion-preserving approaches. Although in traditional cervical spine arthrodesis it is a frequent objective to specifically avoid NSAID because they adversely affect bone fusion, a 2-week course of NSAID has routinely been used after surgery to reduce the incidence of heterotopic, paravertebral ossification with arthroplasty devices.16 "

Conclusion
Key Points
References
Citing Articles
Figures/Tables

http://209.85.135.104/search?q=cache:rYr0advLAMEJ:www.s...r&gl=fr&ct=cln k&cd=3

[Harrison]

Sahuaro, you can invite multiple members to a private topic of discussion -- you just need to know who to invite!

Trace, thx for the reminder article. For what it's worth, I took NSAIDs in low doses (Celebrex & Ibuprofen) in the first few months after ADR.

[Fortitudine]

Well now, that is most interesting and somewhat disturbing to a potential cervical ADR patient. Nine percent is a pretty big number. There were no presentations on HO in cervical ADR at the SAS conference if I recall correctly.

I do remember that most of the NS I saw, including the fusion doc were okay with me not stopping NSAIDs.

[rob_zzz]

reading through the pubmed abstracts and came across this article again (about heterotopic ossification with prodisc-C - see first post in this thread).

There are some interesting numbers in this article - the 9% having a spontaneous fusion is of course worrying, but even more concerning is the following statement:

"Only 33.8% of the patients did NOT show any signs of HO." That means over 60% were showing some signs of HO which is of course a high number.

Also this isn't the first study of this type (I've seen similar for the bryan disc).

Some of the questions this study raises are:

* how accurate is it - in that the determination of HO is done by x-ray analysis so arguably potential errors in the method.

* assuming it is accurate - what techniques are being tried to reduce the rate of HO in ADR. One surgeon I asked said NSAIDS were prescribed to reduce it - but this surely isn't a long term option - but then again maybe if they can stop the process starting in the weeks following surgery its effective.

I wonder if there is also physio therapy that can be done to help reduce it. (e.g. daily exercises to ensure the neck is put through its various ranges of motion).

* how much of an issue is it - i.e. what problems does it cause for the patient? I don't know anything about bone, but is it possible that its a 'flexible' semi-bone that grows, so still allows some motion?

The study was only over two centres - so I guess its possible certain techniques in these centres contributed to the problem - it would be useful to see a more diversified study.