Bioactive glass-ceramic spacer alone versus spacer augmented with ABM/P-15 in single-level ACDF: a retrospective cohort study comparison of fusion rates and clinical outcomes

Abstract

Purpose Achieving early fusion is a critical goal when selecting graft material for anterior cervical discectomy and fusion (ACDF). As bioactive glass-ceramic (BGC-7) cages demonstrate favorable osteoconductive properties, their fusion potential may be enhanced through augmentation with osteoinductive materials. We hypothesized that the synergistic combination of BGC-7 with anorganic bone mineral enhanced with P-15 peptide (ABM/P-15) would lead to optimized fusion outcomes. Methods This retrospective cohort study analyzed 96 patients who underwent single-level ACDF. Fifty-five patients received a BGC-7 cage packed with ABM/P-15 (IF Group), and 41 received a BGC-7 cage alone (NO Group). Fusion was assessed using both computed tomography (CT)-based Bridwell grading and dynamic radiography at 6- and 12-months post operation. Clinical outcomes were evaluated using Visual Analog Scale score, Japanese Orthopedic Association scores, and Short Form-36. In the IF group, absorbable bone hemostat was applied to seal both cage apertures after ABM/P-15 placement to prevent graft migration during impaction. Results The IF group demonstrated significantly higher fusion rates at 6 months (65.5% vs. 41.5%, p = 0.024), with a trend approaching statistical significance at 12 months (92.7% vs. 78.0%, p = 0.067). Multivariate analysis identified ABM/P-15 as an independent predictor of fusion (odds ratio (OR) = 3.93, 95% confidence interval (CI): 1.03-14.95, p = 0.044) after adjusting for smoking, diabetes, hypertension, age, and sex. The IF group demonstrated significantly higher segmental stability based on interspinous motion analysis at 6 months (69.1% vs. 46.3%, p = 0.035), with a trend approaching statistical significance at 12 months (92.7% vs. 78.0%, p = 0.067). Additionally, topographical analysis revealed that fusion was significantly enhanced in the central zone of the cage where the ABM/P-15 was applied. Clinical scores showed meaningful improvement but without significant differences between the two groups. No cases of iatrogenic heterotopic ossification were observed in either group, and no statistically significant differences in the incidence of other serious complications were observed. Conclusion ABM/P-15 augmentation in BGC-7 cages accelerates early fusion progression, with a trend toward higher final fusion rates in single-level ACDF. Multivariate analysis further suggested ABM/P-15 as an independent predictor of fusion. A favorable safety profile, including zero incidence of cage subsidence and heterotopic ossification, supports this combination as a beneficial approach in cervical fusion surgery especially for patients at higher risk of nonunion.