Mid- and Long-term Outcomes after Total Cervical Disc Arthroplasty Compared with Anterior Cervical Discectomy and Fusion: A Systematic Review and Meta-analysis of Randomized Controlled Trials

Introduction: After ACDF to treat symptomatic cervical degenerative disc disease, the loss of motion at the index level due to fusion may accelerate adjacent-level disc degeneration. CDA was developed to preserve motion and reduce the risk of adjacent segment degeneration. Early to mid-term clinical outcomes from RCTs suggest noninferiority of CDA compared with ACDF, but it remains unclear whether CDA yields better mid- to long-term outcomes than ACDF.

Methods: Two independent reviewers searched PubMed, Embase, and the Cochrane Library for RCTs with at least 60 months of follow-up. The risk ratio or standardized mean difference (and 95% confidence intervals) were calculated for dichotomous or continuous variables, respectively.

Results: Eighteen reports of 14 RCTs published in 2014-2023 were included. The pooled analysis demonstrated that the CDA group had a significantly greater improvement in neurological success and Neck Disability Index (NDI) than the ACDF group. The ACDF group exhibited a significantly better improvement in Short Form 36-Health Survey physical component (SF-36 PCS) than the CDA group. Radiographic adjacent segment degeneration was significantly lower in the CDA group at 60- and 84-month follow-ups; at 120-month follow-up, there was no significant difference between the two groups. Although the overall rate of secondary surgical procedures was significantly lower in the CDA group, we did not observe any significant difference at 60-month follow-ups between the CDA and ACDF group and appreciated statistically significant lower rates of radiographic adjacent segment degeneration, and symptomatic adjacent-level disease requiring surgery (SALDRS) at 84-month and 108- to 120-month follow-up. The rate of adverse events, the neck and arm pain scores in the CDA group were not significantly different from those of the ACDF group.

Conclusion : In this meta-analysis of 14 RCTs with 5- to 10-year follow-up data, CDA resulted in significantly better neurological success and NDI scores and lower rates of radiographic adjacent segment degeneration, secondary surgical procedures, and SALDRS than ACDF. ACDF resulted in improved SF-36 PCS scores. However, the CDA and ACDF groups did not exhibit significant differences in overall changes in neck and arm pain scores or rates of adverse events.