The Synergy Disc To Anterior Cervical Discectomy and Fusion

The proposed investigation is a prospective, non-randomized, multi-center, historically controlled comparison of the Synergy Disc to the control of conventional anterior cervical discectomy and fusion (ACDF) surgery in patients with cervical DDD. A total of 175 patients will be enrolled to the investigational group. The investigational group results will be compared to a historical control data from the ACDF control group, which utilized an identical study design. A statistically rigorous observational study design using propensity score (PS) subclassification will be used to demonstrate covariate balance and enhance the quality of inferences regarding effectiveness and safety relative to ACDF control. After investigational device enrollment is complete, but before most investigational device subjects have reached their 24-month endpoint, a data set containing only baseline covariates of prospectively enrolled investigational device patients and historical ACDF control patients will be constructed. The propensity score methods detailed below will be implemented by an outcomes-blinded statistician. A Propensity Score Memo summarizing the proposed observational design will be developed and submitted for review by stakeholders including FDA. The outcomes-blinded statistician will remain blinded until after consensus is achieved that the design is acceptable. This will allow for additional outcomes-blinded PS modeling if required. The objective of this clinical trial is to demonstrate the Synergy Disc is at least as safe and effective as conventional ACDF to treat cervical DDD in subjects who are symptomatic at only one level from C3 to C7 that are unresponsive to conservative management.