BACKGROUND
Introduction of a new surgical technology may result in higher rates of adverse events compared with rates reported in the study performed to gain regulatory approval. The purpose of our study was to describe the incidence of reported adverse events during the first 18 months following US Food and Drug Administration (FDA) approval of the first lumbar arthroplasty device available in the United States and to discern data trends.

METHODS
Reports of adverse events submitted to the FDA in patients receiving the Charité artificial disc were reviewed and pooled by similarity. We analyzed 135 medical device reports filed with the FDA regarding the Charité artificial disc between October 26, 2004, and April 26, 2006. Sixteen reports were excluded for lack of information regarding cause or because described events were vague or unrelated to the procedure.

RESULTS
Rate of adverse events reported to the FDA as a percentage of devices of which the device manufacturer was aware had been dispensed at 6, 12, and 18 months following approval was 0.58%, 2.34%, and 2.13%, respectively. The adverse event reported most frequently through 18 months was anterior migration with reoperation (0.65%); other reported adverse events were, in decreasing order, sizing and malposition errors resulting in reoperation (0.36%), posterior element fracture resulting in

reoperation (0.30%), major vascular injury requiring a blood transfusion (0.23%), and subsidence requiring reoperation (0.20%). Three non–device-related patient deaths were reported following FDA approval. The reported rate of sizing/malposition errors leading to reoperation of 0.36% was the same rate as that seen in the investigational device exemption (IDE) study of the Charité artificial disc. All other reported rates were lower than rates of the same events reported in the study.

CONCLUSIONS
Medical device reporting is an important yet highly anecdotal and incomplete event-tracking process. However, it is the principal means available in the United States for obtaining information on the clinical performance of a device after its approval for sale and does provide some data, albeit imperfect, in this regard. The cumulative medical device reports through the 18 months following FDA approval, measured against the number of devices dispensed, suggests a rate of adverse events that either tracks or is somewhat less than that reported in the IDE study. This suggests that a repeat of the “cage rage,” a “lumbar arthroplasty rage,” has not yet occurred.

Key Words lumbar arthroplasty, total disc replacement, adverse events, complications. SAS Journal. Winter 2007; 1; 8–11.
DOI: SASJ-2006-0001-RR

From the Texas Back Institute, Plano, Tex (Blumenthal and Guyer); the Illinois Neuro-Spine Center at Rush-Copley Medical Center, Aurora (Geisler); the Spine and Scoliosis Center, St Joseph’s Hospital, Towson, Md (McAfee); and the West Coast Spine Institute, Beverly Hills, Calif (Regan).

All authors are consultants to DePuy Spine, Raynham, Mass.

Address correspondence and reprint requests to Scott L. Blumenthal, MD, Texas Back Institute, 6020 W Parker Rd, Suite 200, Plano, TX 75093 (email: sblumenthal@texasback.com).

This submission was received December 7, 2006, and accepted for publication February 13, 2007.

Presented at the 6th Annual Meeting of the Spine Arthroplasty Society, May 9–13, 2006, in Montreal, Québec.

The authors thank Marjorie Eskay-Auerbach, MD, JD, for her assistance in pooling the data for this study.

Institutional review board approval was not required for this study.