A Multicenter, Prospective, Single-arm Evaluation of Fusion Using a Rigorous 5-Factor Scale in Patients Undergoing 2- or 3-Level ACDF Supplemented with a Lineage-Committed Cellular Bone Matrix

Study Design. Prospective, observational multicenter clinical study. Objective. Evaluated cervical spine fusion using a 5-factor scale following multi-level ACDF. Secondary assessments included patient-reported outcome measures for pain and function and complications. Summary of Background Data. Multi-level cervical degenerative spine disease causes pain, instability, and neurological impairment often requiring ACDF. Autologous bone poses harvesting challenges requiring consideration of alternatives such as allogenic and synthetic grafts. ViviGen® cellular bone matrix, containing osteoblasts, osteocytes and bone lining cells, exhibits osteogenic potential making it an option for bone fusion. Evaluating bone fusion from imaging remains a challenge, with no scientific consensus on assessment criteria. Methods. 95 patients with 2- or 3-level ACDF enrolled between July 2016 and July 2018 in a multi-center, prospective study. Follow-up occurred at 6 weeks as well as 3, 6, 12, and optionally at 24 months. Standard ACDF approach was followed with interbody allograft spacer supplemented with ViviGen® cellular bone matrix and cervical plating. Statistical analysis included chi-square, t-test, and ANOVA tests. Results. 5-factor successful fusion rates ranged from 63.8% to 77.6% for the C3-C4 to C6-C7 levels (73.0% overall). Single factor-based successful fusion ranged from 72.4% to 99.5% with bridging bone endplate to endplate present at 80.1% of levels at last follow-up based on independent assessment. CT analysis of a subset of patients identified 96% of levels fused. NDI, SF12 PCS, and VAS scores all improved significantly ( P <0.05) during the follow-up period. Complications were limited and manageable. Only translational motion ≤1.25 mm correlated positively with a clinical outcome (SF12-PCS) on univariate analysis. Conclusion. This study demonstrated favorable fusion outcomes after 2- or 3-level ACDF procedures using a lineage-committed cellular matrix using a rigorous 5-factor scale. Postoperative patient-reported outcomes showed significant improvement in pain and function. Consensus for fusion criteria assessing true bone graft efficacy is needed.