Adjacent Segment Degeneration Following Anterior Cervical Discectomy and Fusion Versus the Bryan Cervical Disc Arthroplasty

BACKGROUND Anterior cervical discectomy and fusion (ACDF) is an established treatment for degenerative disease of the cervical disc, but adjacent segment degeneration or instability may develop long term. The aim of this study was to investigate the risk factors for adjacent segment degeneration following ACDF compared with the use of the Bryan artificial disc for cervical disc arthroplasty (CDA). MATERIAL AND METHODS A prospective comparative study included 93 patients who underwent ACDF or CDA with the Bryan artificial cervical disc between 2002 and 2004, and who had more than eight years of follow-up. There were 29 cases in the CDA group and 39 cases in ACDF group, with a follow-up rate of 73.12%. Clinical results and imaging data were assessed before and after surgery. RESULTS There was no significant difference between the two groups in radiographic parameters at each follow-up time point. There were 19 cases of adjacent segment degeneration (48.72%) in the ACDF group, and 13 cases of adjacent segment degeneration (44.83%) in the CDA group, with no statistically significant difference (P>0.05). Univariate analysis showed that advanced age (OR 1.271, 95% CI 1.005-1.607), low preoperative overall lordosis (OR 0.858, 95% CI 0.786-0.936) and low preoperative segmental lordosis (OR 1.185, 95% CI 1.086-1.193) were significantly correlated with adjacent segment degeneration. CONCLUSIONS Equally good clinical outcomes were achieved with both the ACDF and the Bryan CDA. Increasing patient age was associated with adjacent segment degeneration in both patient groups.