Fusion Sequence and Risk Factors for Pseudarthrosis in Multilevel Anterior Cervical Discectomy and Fusion

Anterior cervical discectomy and fusion (ACDF) is commonly used to treat cervical myelopathy, radiculopathy, and deformity but is associated with complications, including pseudarthrosis, which is particularly frequent in multilevel surgeries. This study aims to compare the fusion rates and mean fusion times across levels in 2-level and 3-level ACDF procedures, while also identifying risk factors associated with pseudarthrosis.

This retrospective study included 119 patients who underwent 2-level or 3-level ACDF with a minimum follow-up of 2 years. Fusion was assessed by measuring angular and linear interspinous motion on dynamic radiographs at 1.5, 3, 6, 12, and 24 months. Patient demographics, cage characteristics, and surgical methods were analyzed to identify risk factors for pseudarthrosis using Kaplan-Meier estimates and Cox proportional hazards regression.

The cumulative fusion rate over 24 months was 73.1% in the 2-level group and 57.7% in the 3-level group, with a shorter median fusion time in 2-level ACDF (13.81 months) compared with 3-level ACDF (18.35 months, P = .049). In the 3-level ACDF group, the middle level fused the fastest (2.71 months), followed by the cranial and caudal levels (7.96 months vs 18.12 months, P < .001). Polyetheretherketone cage usage (hazard ratios = 2.309, P = .052) and 2-level or 3-level ACDF (hazard ratios = 2.008, P = .041) were associated with increased pseudarthrosis risk.

Multilevel ACDF procedures, particularly at the caudal levels, demonstrate lower fusion rates and longer fusion times. Polyetheretherketone cages may pose a higher pseudarthrosis risk in multilevel ACDF. These findings underscore the importance of selecting appropriate materials and techniques in multilevel ACDF to improve fusion outcomes. Further studies are warranted to optimize fusion strategies, especially for caudal levels in multilevel ACDF.