Comparison of Fusion versus Nonunion After 4-Level and 5-Level Anterior Cervical Diskectomy and Fusion With Anterior Plate Fixation

Nonunion remains a concern in multilevel anterior cervical discectomy and fusion (ACDF), yet there are limited data on nonunion after 4 to 5-level ACDF. In fact, the largest series on 4-level or 5-level ACDF focused specifically on the swallowing outcomes.To assess nonunion after 4 to 5-level ACDF.Forty-one patients treated with 4 to 5-level ACDF with minimum of 12-month radiographic follow-up were retrospectively reviewed. Nonunion was found in 25 patients (61%) and 42 levels (25%) and complete fusion in 16 (39%) patients and 126 levels (75%). The 2 groups were further compared.One-level nonunion was by far the most common pattern compared with multilevel nonunion. Nonunion occurred more frequently at the caudal than the cranial or middle segments ( P < .0001). There were significantly more subsidence ( P < .0001) and screw fractures/pullouts ( P < .0001) in the nonunion compared with the fusion group. The symptomatic patients were significantly younger than the asymptomatic patients ( P = .044). The symptomatic levels were significantly more than asymptomatic levels ( P = .048). Equal proportion of patients implanted with allograft and polyetheretherketone had nonunion. However, there were markedly more nonunion than fused levels with allograft and more fused than nonunion levels with polyetheretherketone ( P = .023). The reoperation rate was 24.4% and mostly due to nonunion. There were no reoperations within 90 days of the primary surgery.The nonunion rate for 4-level and 5-level ACDF may be higher than previously reported. Symptomatic nonunion remains a major reason for reoperation after multilevel ACDF. Baseline characteristics that negatively affect fusion may be obviated by careful patient selection.