Smoking Attenuates the Advantages of Cervical Disc Arthroplasty Over Fusion: A Comparative Analysis of ACDR and ACDF Outcomes.

OBJECTIVE: To compare anterior cervical disc replacement (ACDR) and anterior cervical discectomy and fusion (ACDF) in smokers and nonsmokers.

SUMMARY OF BACKGROUND DATA: Smoking is a well-established risk factor after fusion-based spine surgery, whereas ACDR does not depend on bony fusion. This prompts interest in ACDR for smokers, but comparative data remain limited.

METHODS: Patients aged ≥18 years undergoing ACDR or ACDF for cervical myelopathy or radiculopathy from 2017 to 2023 were stratified by smoking status. Primary outcomes were length of stay (LOS), adjacent segment disease (ASD), reoperation, and subsidence; secondary outcomes were PROMIS Global Mental Health (GMH) and Global Physical Health (GPH) through 2 years. Regression within each stratum adjusted for age, Charlson Comorbidity Index, and operative levels. Procedure-by-smoking interactions were fitted on the full cohort, with Firth penalized regression for sparse outcomes, mixed-effects models for PROMIS, and time-to-event analysis for complications.

RESULTS: 242 patients were included (60 ACDR, 182 ACDF). Among non-smokers, ACDR was associated with lower reoperation (2.4% vs. 13.9%; adjusted OR 3.91, P=0.036) and subsidence (12.2% vs. 25.2%; adjusted OR 2.12, P=0.047), shorter LOS (+0.31 d for ACDF, P=0.006), and higher 2-year GPH (50.5±6.6 vs. 44.1±6.8, P<0.001). Among smokers, only the shorter LOS persisted (+0.43 d, P=0.02); no differences were seen in reoperation, subsidence, ASD, or patient-reported outcomes. In interaction testing, only 2-year GPH reached significance.

CONCLUSIONS: The advantages of ACDR among non-smokers were absent in smokers. These findings indicate that smoking may attenuate the procedure-specific advantages of ACDR and that smoking status should be considered a possible determinant of surgical effectiveness. Smoking cessation should be emphasized as an integral component of preoperative counseling and surgical planning, and the choice between ACDR and ACDF in active smokers should be made with the understanding that the expected benefits of ACDR may not be present in this population.

STUDY DESIGN: Retrospective cohort study.