Randomized controlled trials comparing cervical disc arthroplasty and anterior cervical discectomy and fusion outcomes in degenerative spine disease: a systematic review and meta-analysis.

Anterior cervical discectomy and fusion (ACDF) is an established treatment for cervical degenerative disc disease; however, the procedure can cause loss of cervical spine range of motion and potentially accelerate adjacent segment degeneration. Cervical disc arthroplasty (CDA) seeks to preserve native motion of the cervical spine, which can theoretically reduce the incidence of adjacent level degeneration. The literature regarding the relative efficacy of ACDF versus CDA remains inconsistent. In this study, the authors investigate the difference in outcomes between ACDF and CDA and identify factors contributing to the heterogeneity in the literature. The Ovid, Embase, Scopus, Cochrane, and ClinicalTrials.gov databases were systematically searched from inception to September 5, 2023, for randomized controlled trials (RCTs) comparing ACDF and CDA for degenerative disc disease. Studies were extracted by two authors and verified by a third. Random-effects meta-analysis was performed. The primary outcome was the difference in clinical outcomes between the two surgical groups. The secondary outcomes were the differences in radiological outcomes, surgical characteristics, complication rates, and hospital lengths of stay. The study was registered with the International Prospective Register of Systematic Reviews (PROSPERO; registration no. CRD42023469204) and adhered to the PRISMA guidelines. From 584 articles uploaded to the Covidence platform for screening, 35 studies derived from 25 RCTs were included in this systematic review and meta-analysis. A total of 4530 patients were treated with ACDF (2081) and CDA (2449). Forty-six percent of the patients (2063) were male, and the mean age of the study cohort was 45 ± 3 years. In terms of the primary outcome, CDA showed higher rates of neurological and overall success. Regarding the secondary outcomes, CDA demonstrated a significantly lower rate of adjacent level disease, higher rate of heterotopic ossification, and greater range of motion at the operated level. Additionally, CDA had lower rates of reoperation but significantly longer operative times than ACDF. The inclusion of myelopathic patients and variations in follow-up between the surgical groups contributed to the observed effect heterogeneity among studies. In this study, CDA showed comparable or potentially greater success in overall and neurological outcomes, along with a lower incidence of adjacent level degeneration and reoperation rates but longer operative times.