Comparison of 1-Level Versus 2-Level Anterior Cervical Discectomy and Fusion: Clinical and Radiographic Follow-Up at 60 Months

Study Design.This study represents a posthoc analysis of data collected from 2 control arms of a prospective, randomized study.Objective.The purpose of this study was to compare results of patients undergoing 1- versus 2-level anterior cervical discectomy and fusion (ACDF).Summary of Background Data.For single-level ACDF, reported outcomes have generally been good; however, results for 2 levels have been less consistent.Methods.This 60-month follow-up study was based on data from the prospective Food and Drug Administration regulated Mobi-C artificial disc trial. Serving as the control, ACDF was performed at 1 level in 81 patients and 2 levels in 105 patients. Study selection criteria, fusion technique, and outcome measures were identical, with the only exception being the number of levels that were pathological and operated.Results.Neck Disability Index (NDI) scores, visual analog scales assessing neck and arm pain, and SF-12 scores improved significantly in both groups. Significant differences were observed between groups on NDI and SF-12 PCS scores through 60 months. Fusion rates were 93.3% in the 1-level group and 86.1% in the 2-level (60 months, not significantly different). Adjacent segment degeneration occurred in 54.7% of patients at the superior level and 44.7% at the inferior segment in the 1-level group and 70.8%, and 55.0% respectively in 2-level patients (trend at superior level; 0.05<P<0.10). Subsequent index level surgery was performed in 11.1% of single-level patients versus 16.2% of the 2-level group (not significantly different).Conclusion.One- and 2-level ACDF groups improved significantly and maintained improvement throughout 60 month follow-up. When comparing groups, outcomes were often similar, though the 1-level group demonstrated higher fusion rates at 6 and 12 months, greater improvement in NDI scores from 18 to 60-month follow-up, and greater improvement in SF-12 PCS from 12 to 60 months.Level of Evidence: 2