Comparison of Outcomes After Anterior Cervical Discectomy and Fusion Using Bioactive Glass-Ceramic Spacer-7 (NOVOMAX-FUSION) and an Allograft Spacer: A Retrospective, Case-Matched, Multicenter Study

The bioactive glass-ceramic spacer (BGS)-7, a biosynthetic intervertebral fusion material introduced in 2014, has not been the subject of comparative clinical studies on anterior cervical discectomy and fusion (ACDF) surgery. This study, for the first time, aims to compare the radiological and clinical outcomes of the renewed BGS-7, released in 2019, with those of an allograft spacer. The comparison includes a finite element analysis of the biomechanical properties of each implant, adding a novel dimension to the research. We prospectively followed up on 29 patients who underwent ACDF using BGS-7 as the experimental group. To select a control group for comparison, 253 patients with level 1 ACDF with an allograft spacer between 2012 and 2022 were selected from our hospital. Using propensity score matching, 27 and 54 patients in the BGS-7 and allograft groups, respectively, were selected. The average subsidence length was 1.02 +/- 1.44 mm per level in the BGS-7 group and 2.27 +/- 2.25 mm per level in the allograft group. Subsidence was observed in 14 of 54 patients (25.9%) in the allograft group and one of 27 patients (3.7%) in the BGS-7 group (p = 0.016). In the allograft group, 16 of the 54 patients (29.6%) monitored for 6 months achieved satisfactory fusion outcomes with grades 4 and 5. Thirty-eight of 54 patients (70.4%) followed up for > 1 year in the allograft group achieved adequate fusion outcomes with grades 4 and 5. In the BGS-7 group, 17 of the 27 patients (63.0%) monitored for 6 months achieved satisfactory fusion results with grades 4 and 5. Twenty-three of the 27 patients (85.2%) followed up for > 1 year obtained adequate fusion outcomes with grades 4 and 5. There was a significant difference in the fusion rates between the two groups at 6 months (p = 0.008). BGS-7 is a reliable instrument for ACDF with no instances of instrumental failure. The BGS-7 group had positive clinical outcomes after surgery without any untoward events, and an early fusion rate with the creation of a bone bridge was noted during the 6-month follow-up period. Our findings not only indicate the safety of BGS-7 but also its practicality as a substitute for allografts in ACDF, instilling confidence in its application.