Retrieval Analysis of a ProDisc-L Total Disc Replacement

[Justin]

Journal of Spinal Disorders & Techniques. 22(4):290-296, June 2009.

Retrieval Analysis of a ProDisc-L Total Disc Replacement.

Choma, Theodore J. MD *; Miranda, Jose MD +; Siskey, Ryan BS ++ [S]; Baxter, Ryan BS ++ [S]; Steinbeck, Marla J. MT(ASCP), PhD [S]; Kurtz, Steven M. PhD ++ [S]
Institution (*)Orthopaedic Surgery Department, University of Missouri, Columbia, MO
(+)Orthopaedic Surgery Service, Dwight D Eisenhower Army Medical Center, Fort Gordon, GA
(++)Exponent Inc
([S])School of Biomedical Engineering, Science, and Health Systems, Drexel University, Philadelphia, PA

Study Design: We retrieved a functioning ProDisc-L total disc replacement and associated tissues at 16 months of service life.

Objective: To analyze a previously unreported mode of implant malpositioning, wear mechanisms, and polyethylene locking mechanism, and to study retrieved periprosthetic tissues.

Summary of Background Data: The clinical performance of polyethylene in the context of total disc replacements remains poorly understood. In the ProDisc-L, the polyethylene core is fixed to the inferior metal endplate through a mechanical interference locking mechanism similar to those used in tibial total knee components. This case represents the third report of an explanted ProDisc-L prosthesis, and the first reported case of posterior malpositioning with this device.

Methods: The implant was removed via a transperitoneal approach. Its polyethylene core was evaluated for burnishing, fracture, third-body abrasion, and permanent deformation. An identical, never-implanted set of polyethylene and endplate components served as controls for the microscopic evaluation of wear. Two tissue samples were collected from a region adjacent to the failed implant to evaluate tissue morphology and inflammation. Hematoxylin and eosin-stained tissue sections were also evaluated for the presence of polyethylene debris by polarized light microscopy.

Results: The implant was removed without serious incident, although there were incidental venotomies. The patient went on to solid arthrodesis. We found minimal wear, oxidation, and periprosthetic tissue reaction, as might be expected given the short-term duration of implantation and its reason for revision. No evidence was found of malfunction or improper deployment of the locking mechanism. Burnishing seemed to be the result of short-term impingement. Some areas of the tissue matrix showed evidence of early cell degeneration, and some of these areas contained polyethylene particles identified by polarized light microscopy.

Conclusions: A larger series of implant retrievals will be needed to investigate possible wear and the biologic response to increased particle generation.

(C) 2009 Lippincott Williams & Wilkins, Inc.

[Justin]

Here's another publication on ProDisc-L retrieval after a patient had the device dislocate when they returned to heavy lifting --> Anterior Revision of a Dislocated ProDisc Prosthesis at the L4-5 Level.

I'm sure as everyone can see, there are significant risks during ADR revision operations. In these publications, it describes patients losing up to 5 liters of blood.

I'm not posting these revision articles to scare people, but to make the case that artificial disc replacement surgery is a major spine surgery and that revision to fusion is not nearly as easy as many patients and surgeons initially thought when the FDA Clinical Trials were just starting in the United States.

[mark-Perth]

Hey Justin

Thanks for adding those articles, Its definately important for people to realise that a revision ADR operation is not a simple operation and extremely dangerous and not just a simple case of a fusion before they have surgery. These ones were removed which I have found is extremely rare as most surgeons prefer to just fuse the disc inplace unless it is essential to have it removed as that is much safer but rarely gets a great result. I seriously doubt and have been told by many surgeons that I will not get as good a result from a fusion after a failed ADR as if I had just gone straight to a fusion to start with. It is not that simple and easy but most people think they are going to end up with the same thing in the end so why not try an ADR first and if that fails have it fused. If only.
Also there has been a trend of recent to start to remove the discs laterally (XLIF) to avoid the complications and dangers of a repeat anterior operation but this cant be done at L5/S1 only levels above. It definately seems like a much safer option but does have some risks of course.

Mark

[ajj1001]

Definitely something you need to consider before having an ADR surgery, what happens if it fails. Hopefully they will get better at removing devices or designing artificial discs that are more easily removed.

[Justin]

Definitely something you need to consider before having an ADR surgery, what happens if it fails. Hopefully they will get better at removing devices or designing artificial discs that are more easily removed.

AJ,

This is a very good point--there are many devices in the works, so it should be interesting. Revision techniques are being refined and surgeons are working to find the best way to revise a "failed" ADR so that patients have the best possible outcome after explantation of a device.

[Justin]

Hey Justin

Thanks for adding those articles, Its definately important for people to realise that a revision ADR operation is not a simple operation and extremely dangerous and not just a simple case of a fusion before they have surgery. These ones were removed which I have found is extremely rare as most surgeons prefer to just fuse the disc inplace unless it is essential to have it removed as that is much safer but rarely gets a great result. I seriously doubt and have been told by many surgeons that I will not get as good a result from a fusion after a failed ADR as if I had just gone straight to a fusion to start with. It is not that simple and easy but most people think they are going to end up with the same thing in the end so why not try an ADR first and if that fails have it fused. If only.
Also there has been a trend of recent to start to remove the discs laterally (XLIF) to avoid the complications and dangers of a repeat anterior operation but this cant be done at L5/S1 only levels above. It definately seems like a much safer option but does have some risks of course.

Mark

Mark, you bring up very good points. There is also a thread on Charite removal that might interest you as well --> Removal of the Charite Lumbar Artificial Disc Prosthesis: Surgical Technique.

Thanks for your insight.

[Phylly]

Justin,
I also want to thank you for posting these articles. I feel so lucky to have survived the removal from the anterior approach. I did think that if my ADR's failed it would not be a problem to remove them to a fusion easily. Not so at all. It is also confusing not only to find a doctor willing to do this but also to pick an approach that will be successful. Complications can arise in all directions. I also hope and well said by others that as new technology appears there will be better methods for their removal if necessary. It is so important to have this information beforehand. I can write volumes on how ignorant I was. Knowing what I know now, I am not sure I would do it again?
Phylly

[Justin]

Justin,
I also want to thank you for posting these articles. I feel so lucky to have survived the removal from the anterior approach. I did think that if my ADR's failed it would not be a problem to remove them to a fusion easily. Not so at all. It is also confusing not only to find a doctor willing to do this but also to pick an approach that will be successful. Complications can arise in all directions. I also hope and well said by others that as new technology appears there will be better methods for their removal if necessary. It is so important to have this information beforehand. I can write volumes on how ignorant I was. Knowing what I know now, I am not sure I would do it again?
Phylly

Phylly, your experience with removal of artificial disc replacement devices via an anterior approach is priceless for those patients contemplating ADR surgery in the future. You are an encouragement to many Spine Patients suffering with chronic pain daily, even after placement of an artificial disc replacement device.

Unfortunately, studies like the ones posted above are needed. I do hope that there will be better methods for device removal down the road. We are starting to see some of the successful removal techniques utilize a lateral approach; thus, avoiding (or reducing) the likelihood of tearing the scarred-down aorta and vena cava. The aorta and vena cava can be scarred-down over the vertebral bodies after the initial anterior (abdominal) approach that was used to place the artificial disc replacement devices.

Possible revision / removal of artificial disc replacement devices is something that all Spine Patients should be aware of before undergoing an operation. These revision / removal procedures can be life-threatening and have inherent risks that need to be stressed preoperatively to all Spine Patients contemplating artificial disc replacement surgery.