Reoperation Risks Between Cervical Disc Arthroplasty and Anterior Cervical Discectomy with Fusion: It is Not Always About Adjacent Segment Disease.

Abstract

Retrospective cohort study. To determine risks of reoperations for adjacent segment disease (ASD) and all-cause reoperations following cervical disc arthroplasty (CDA) versus anterior cervical discectomy with fusion (ACDF). To reduce ASD risk, CDA was developed to preserve mobility. While studies show CDA lowers ASD reoperation rates, few have included all-cause reoperation risks. Using data from a National Spine Registry, patients (18-60 years old) with cervical degenerative disc disease who underwent a primary 1-level and 2-level CDA or ACDF were selected. Patients with ACDF were 3:1 propensity-score matched to CDA patients. Cox Proportional-Hazards regression was used to evaluate reoperations for ASD and all-cause risks. Hazard ratios (HR) and 95% confidence intervals (CIs) were presented; P<0.05 was the significance threshold. The cohort consisted of 6,318 patients with a mean follow-up of 6.9 years Propensity score matching yielded 809 CDA patients and 2,427 ACDF patients. In Cox Regression analysis, a lower risk of reoperation for ASD was observed for 1-level CDA compared to ACDF (HR=0.86, 95% CI=0.64-1.15, P=0.31) but without statically significance. For 1-level and 2-level no difference in all-cause reoperation risks was found (HR=0.84 95% CI=0.64-1.12, P=0.25) and (HR=0.67 95% CI=0.33-1.37, P=0.27) respectively. Mean time to ASD reoperation was 3.9 years (SD=3.5) for CDA and 4.4 years (SD=3.1) for ACDF. With nearly 7 years of average follow-up, this large registry-based study showed that 1-level CDA did not significantly reduce the risk of ASD, or all-cause reoperations compared to ACDF. Similar results were only seen for all-cause reoperations in 2-level CDA. Importantly, ASD reoperations occurred within 4-5 years on average, underscoring that while CDA preserves motion, the risk of subsequent surgery remains. These findings highlight the real-world performance of CDA and may reflect other factors that increase all-cause reoperations which may have been underreported.