Cervical disc arthroplasty versus anterior cervical discectomy and fusion: an analysis of the Michigan spine surgery improvement collaborative database.

BACKGROUND CONTEXT: Anterior cervical discectomy and fusion (ACDF) and cervical disc arthroplasty (CDA) are established surgical options for the treatment of cervical radiculopathy, myelopathy, and cervical degenerative disc disease. However, current literature does not demonstrate a clear superiority between ACDF and CDA.

PURPOSE: To investigate procedural and patient-reported outcomes of ACDF and CDA among patients included in the Michigan Spine Surgery Improvement Collaborative (MSSIC) database.

DESIGN: Retrospective study of prospectively collected outcomes registry data.

PATIENT SAMPLE: Individuals within the MSSIC database presenting with radiculopathy, myelopathy, or cervical spondylosis refractory to typical conservative care undergoing primary ACDF or CDA from January 4, 2016, to November 5, 2021.

OUTCOME MEASURES: Perioperative measures (including surgery length, length of stay, return to OR, any complications), patient-reported functional outcomes at 2-year follow-up (including return to work, patient satisfaction, PROMIS, EQ-5D, mJOA).

METHODS: Patients undergoing ACDF were matched 4:1 with those undergoing CDA; propensity analysis performed on operative levels (1- and 2- level procedures), presenting condition, demographics, and comorbidities. Initial comparisons performed with univariate testing and multivariate analysis performed with Poisson generalized estimating equation models clustering on hospital.

RESULTS: A total of 2,208 patients with ACDF and 552 patients with CDA were included. Baseline demographics were similar, with younger patients undergoing CDA (45.6 vs. 48.6 years; p<.001). Myelopathy was more frequent in ACDF patients (30% vs. 25%; p=.015). CDA was more frequently planned as an outpatient procedure. Length of stay was increased in ACDF (1.3 vs. 1.0 days; p<.001). Functional outcomes were similar, with comparable proportions of patients meeting minimal clinically important difference thresholds in neck pain, arm pain, PROMIS, EQ-5D, and mJOA score. After multivariate regression, no significant differences were seen in surgical or functional outcomes.

CONCLUSIONS: This study demonstrates similar outcomes for those undergoing ACDF and CDA at 2 years. Previous meta-analyses of CDA clinical trial data adhere to strict inclusion and exclusion criteria required by clinical studies; this registry data provides "real world" clinical outcomes reflecting current practices for ACDF and CDA patient selection.