Friday, December 20, 2013
Cervical Arthroplasty in the Long-term—Nothing Lasts Forever?
Cervical arthroplasty (CA) has been promoted as a safe, effective alternative to ACDF that could theoretically reduce the rate of adjacent segment disease (ASD) and has been associated with lower re-operation rates out to five years in some studies.1,2 Additional advantages include the avoidance of post-operative bracing and earlier return to activities. While lumbar disk replacement has failed in large part due to it being used for a non-surgical disease, cervical radiculopathy responds very well to decompression, and CA has been shown to have similar outcomes to ACDF in short- and medium-term follow-up. The biggest concern about CA is its long-term durability, and there have been very few reports from the industry-sponsored trials about device performance beyond four years. In an effort to fill this void, Dr. Hacker and his colleagues from Oregon reviewed their very long-term (over four years) outcomes for patients enrolled in FDA trials evaluating the Bryan and Prestige cervical disks. Ninety four patients were enrolled, and they present a case series of five patients with device related complications presenting from four to six years after surgery. Three patients presented with neck and upper extremity pain and chose to undergo revision surgery. One patient had posterior subluxation of the device resulting in cord compression, one had marked bone loss and failure at the bone-device interface, and one had severe subsidence leading to kyphosis. Two patients presented with neck pain and findings of lucency at the bone-device interface and were treated non-operatively. The authors state that the trial patients treated with ACDF and CA had similar rates of ASD, and they did not analyze these patients.
While case series rarely provide data from which strong conclusions can be drawn, they are helpful to identify complications or rare events. This study is an example of a helpful case series describing very long-term complications associated with CA that have rarely been discussed in the literature. This study does not allow for the determination of the rate of these events or calculation of a Kaplan-Meier survival curve for the devices, but it does make the spine community aware of potential long-term failures. Until the FDA trials have reported ten and fifteen year outcomes, the long-term durability of these devices will remain unknown. Given that the only significant long-term complication associated with ACDF that has gone onto successful fusion is ASD and that CA has not yet been shown to reduce ASD, it seems as though CA provides marginal benefit with a yet unknown risk of long-term failure. It may be that long-term studies demonstrate that CA reduces ASD and has a low long-term failure rate. Another possibility is that it offers minimal benefit and has a finite lifespan. Until we have the results of very long-term studies, surgeons and their patients will have to make this treatment decision based on philosophy rather than evidence.
Please read Dr. Hacker’s article on this topic in the December 15 issue. Does this article change your approach to cervical arthroplasty? Let us know by leaving a comment on The Spine Blog.
Adam Pearson, MD, MS
Associate Web Editor
1. Zigler JE, Delamarter R, Murrey D, Spivak J, Janssen M. ProDisc-C and Anterior Cervical Discectomy and Fusion as Surgical Treatment for Single-Level Cervical Symptomatic Degenerative Disc Disease: Five-Year Results of a Food and Drug Administration Study. Spine 2013;38:203-9.
2. Zigler JE, Glenn J, Delamarter RB. Five-year adjacent-level degenerative changes in patients with single-level disease treated using lumbar total disc replacement with ProDisc-L versus circumferential fusion. J Neurosurg Spine 2012;17:504-11.