Disc to Disc

Study Design: Prospective, randomized, multicenter investigational device exemption clinical trial, level I evidence. Objective: To compare an investigational (prodisc, Centinel Spine) total disc replacement (cTDR) to an approved (Mobi-C, Highridge Medical) cTDR at 2 contiguous levels. Summary of Background Data: Previous investigational device exemption (IDE) clinical trials at 2 contiguous levels have compared cTDR to anterior cervical discectomy and fusion (ACDF). These trials have shown superiority of cTDR to ACDF. Methods: Under Institutional Review Board approval, 433 patients were randomized in a 2:1 (investigational: control) ratio. All patients were seen for follow-up to 24 months. On the basis of an adaptive Bayesian model, the first analysis of the data can be reported at 50% of subjects reaching 24-month follow-up. The primary endpoint was composite clinical success (CCS) at 24 months. Secondary endpoints collected were Visual Analog Score (VAS) neck and arm pain, and Short-Form-12 (SF-12). Results: At 24 months, the CCS was achieved in 88.2% of the investigational compared with 86.8% of the control group (95% CI: −7.5% to 11.1%; P = 0.994) confirming non-inferiority. NDI showed statistically significant improvement from preoperative (investigational: 58.8±15.8: control 57.2±15.9) to 24 months (investigational: 14.2±16.7: control 14.5±15.9) in both groups but no difference between treatments. NDI success was achieved in 95.3% of the investigational patients and 94.2% of the control patients and was not statistically different between groups ( P > 0.99). All secondary endpoints consistently showed similar improvement from baseline for both groups, but none of the measures showed a statistically significant difference between treatments. Conclusions: This is the first randomized study comparing 2 cervical disc designs with different mechanisms of action. At 24 months, both designs were found safe and effective at 2 levels.