Artificial Discs in Cervical Disc Replacement: A Meta-Analysis for Comparison of Long-Term Outcomes

Cervical disc replacement (CDR) has emerged as an alternative to anterior cervical discectomy and fusion for the surgical treatment of degenerative cervical disc disease. Although comparison of the 2 techniques has been studied in the literature, a thorough assessment of all artificial discs between each has not been performed. The objective of the present study was to examine the long-term outcomes of 5 artificial discs. An electronic literature search was conducted for studies of CDR devices for all years available. Only articles in English were included. Heterotopic ossification, adjacent segment disease, and reoperation comprised the primary outcomes of interest. Pooled descriptive statistics with effect size (ES) and 95% confidence interval were used to synthesize the outcomes for each device. Sixty-five studies (n = 5785) were included in the analysis. Comparison of the incidence of grade III/IV heterotopic ossification showed a significant variability between the 5 devices (P < 0.001) with ProDisc-C (ES, 38%; 95% confidence interval [CI], 24%–54%) having the highest incidence rate. Overall rate of adjacent segment disease was 14% (95% CI, 7%–23%) with significant associated heterogeneity (P < 0.001). Regarding 2-year reoperation risk, the overall incidence rate was 2% (95% CI, 1%–3%), with nonsignificant variability between devices (P = 0.63). The highest rate was observed in the Discover group (ES, 4%; 95% CI, 0%–13%). The results of the present meta-analysis indicate that surgical and clinical outcomes may differ among different CDR devices. These findings may assist surgeons in tailoring their decision making to specific patient profiles. Future multicenter efforts are needed to validate associations found in this study.