Three-Level Anterior Cervical Discectomy and Fusion (ACDF) is Associated With Higher Rates of Instrumentation Failure and Shorter Time to Reoperation Than One-Level or Two-Level ACDF

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: Evaluate the impact of increasing levels of cervical fusion on alignment and outcomes. BACKGROUND: One-level anterior cervical discectomy and fusion (ACDF) adequately restores cervical alignment and offers favorable postoperative outcomes. However, comparative studies following increasing levels of fusion are lacking. MATERIALS AND METHODS: Patients who underwent one-level to three-level ACDFs were identified. Demographics, spinopelvic alignment, and clinical outcomes were compared up to one-year postoperatively. Multivariate regressions, accounting for age, gender, Charlson comorbidity index (CCI), osteoporosis, and baseline cervical deformity were performed to examine the association between levels of ACDF and postoperative outcomes. Cox regression analysis was also performed to evaluate the association between levels of ACDF and time to reoperation. RESULTS: Among 279 patients (mean age: 54.1 yr, 49% female, mean CCI: 0.6), 110 had one-level, 137 had two-level, and 32 had three-level ACDFs. Perioperatively, estimated blood loss (19.1 vs. 25.3 vs. 33.8 mL) was comparable and procedure time (131.2 vs. 167.9 vs. 225.9 mL) increased with increasing levels of ACDF, with regression analysis revealing higher odds of both in three-level ACDFs ( P <0.05). Postoperatively, instrument failure (1% vs. 4% vs. 13%, P =0.008) and cage subsidence (15% vs. 28% vs. 44%, P =0.001) rates increased with increasing levels of ACDF, with regression analysis showing higher odds of both in three-level ACDFs ( P <0.05). Cox regression revealed a hazards ratio of 1.2 (95% CI=0.5-3.3) for two-level ACDF and 25.9 (95% CI=2.8-239.8) for three-level ACDF in predicting time to reoperation relative to one-level ACDF. Lordotic correction and improvement in PROMs were comparable across cohorts ( P >0.05). CONCLUSION: Multilevel ACDF yielded comparable improvements in sagittal cervical alignment and PROMs, but was associated with worse in-hospital and out-of-hospital outcomes than single-level ACDF. In addition, it lowered the time to reoperation following the initial procedure. Surgeons should, thus, carefully select operative levels based on clinical and radiographic factors. LEVEL OF EVIDENCE: Level IV.