Allograft vs Bioactive Glass-Ceramic Cages in Anterior Cervical Discectomy and Fusion: Long-Term Randomized Trial Follow-up

Study designObservational extended follow-up of a randomized controlled trial.ObjectiveTo compare mid-to long-term clinical and radiographic outcomes of allograft vs bioactive glass-ceramic (BG) cages for anterior cervical discectomy and fusion (ACDF) while preserving the original random allocation.MethodsAll patients randomized in the parent RCT underwent 1-2 level ACDF between August 2017-August 2022 (allograft n = 18; BG n = 22) were followed through August 2025. We compared patient-reported outcomes-neck disability index (NDI) and visual analogue scale (VAS)-cervical sagittal alignment, including C2-7 lordosis (CL), T1 slope, and T1 slope minus cervical lordosis (T1sCA), and CT-based subsidence using adjusted linear mixed-effects models (LMMs); fusion (Bridwell I-II) was compared between groups.ResultsAmong 40 patients, 90% had follow-up longer than 24 months with mean follow-up 53.5 ± 25.2 months. Both groups showed significant within-group improvements in all patient reported outcomes. However, at the last visit, between-group differences were non-significant for the primary endpoints: NDI (BG-allograft -0.98, 95% CI -9.17 to 7.21; P = .814) and C2-7 lordosis (BG-allograft -0.19°; P = .917). Other endpoints (VAS, T1sCA, subsidence, fusion) were likewise similar. No cage breakage or migration occurred; adverse events were minor.ConclusionOver multi-year follow-up, bioactive glass-ceramic cages provided equivalent clinical improvement and radiographic stability to allograft cages after ACDF.