Comparison of Reoperation Risks for Anterior Cervical Discectomy and Fusion (ACDF) and Cervical Disc Arthroplasty (CDA): A Retrospective Cohort Study from a Multicenter Healthcare System

Introduction: Cervical degenerative disc disease (DDD) has historically been treated with ACDFs, however, the risks of adjacent segment disease (ASD) have been problematic. Cervical disc arthroplasty (CDA) was introduced as an alternative to preserve cervical mobility to reduce ASD. Few studies have evaluated the long-term outcomes of ACDFs compared to CDA using reoperation rates for all-cause in large patient cohorts.

Methods: Retrospective analysis from the Kaiser Permanente Spine Registry identified a propensity score-matching cohort (3:1, ACDF vs CDA) of adult patients (> 18 years old) with cervical degenerative disc disease who had primary ACDF or CDA between C3 and C7. Patients were followed until validated reoperation, membership termination, death, or end of study. Cox-Proportional Hazards regression was used to evaluate reoperation rates. 10-year crude cumulative incidence rates were calculated.

Results: 5,830 patients were in the original cohort. Propensity-score matching found 2,286 ACDF patients matched to 762 CDA patients. The average age was 48.3 years (SD±7.9) and average follow-up was 6.5 years (SD±4.0). For CDA versus ACDF we found a 10-year reoperation rate of 8.9% versus 12.4%; ASD rate of 5.7% vs 9.3%and hardware failure 2.8% vs 0.2%. In regression analysis, no difference in all-cause reoperation risk was observed (HR=0.79, 95% CI=0.60-1.05); a lower risk of ASD was found in CDA group (HR=0.72, 95% CI=0.54-0.96), however, there was a higher risk of hardware failure (HR=13.85, 95% CI=4.70-40.84).

Conclusion : In a large matched cohort, CDA was associated with a 30% reduction in operative ASD but a significantly higher risk of hardware failure.