i-Factor™ Bone Graft Versus Demineralized Bone Matrix for Single-Level Anterior Cervical Discectomy and Fusion: A Propensity Score-Matched Analysis

Background/Objectives: i-Factor™ Bone Graft is a composite bone substitute containing P-15 synthetic collagen fragment that has demonstrated noninferiority to local autograft in single-level anterior cervical discectomy and fusion (ACDF); however, direct head-to-head comparisons with demineralized bone matrix (DBM) using contemporary 3D-printed titanium cages are lacking. The aim of this retrospective study was to compare radiographic fusion rates, segmental stability, and clinical outcomes between i-Factor™ and DBM in single-level ACDF, with a particular focus on the early time course of fusion. Methods: A retrospective propensity score-matched cohort study was conducted in patients with single-level cervical degenerative disc disease (cervical disc herniation, cervical spondylotic radiculopathy, or cervical spondylotic myelopathy) operated between December 2021 and January 2024 at a single tertiary care hospital. Seventy-six consecutive patients undergoing single-level ACDF with 3D-printed titanium cages were matched 1:1 (i-Factor™ vs. DBM) on age, sex, and operative level. Fusion status was assessed by serial dynamic radiographs at 1, 3, 6, and 12 months and by 3D-CT at 12 months in all patients (with additional CT at earlier timepoints when plain films were equivocal), by two independent spine surgeons blinded to graft type; inter-rater agreement (Cohen’s κ) was computed. Results: Mean follow-up was 18.1 months. Fusion rates for i-Factor™ at 3, 6, and 12 months were 94.7%, 100%, and 100%, respectively, compared to 71.1%, 84.2%, and 94.7% for DBM. The differences were statistically significant at 3 months (p = 0.047) and 6 months (p = 0.012), but not at 12 months (p = 0.493). Inter-rater agreement was almost perfect (κ = 0.86–1.00). No adverse reactions or device-related complications were observed. Conclusions: In this matched cohort, i-Factor™ was associated with significantly faster fusion than DBM in single-level ACDF, with similar 12-month fusion rates. No adverse reactions were observed, although the sample size is insufficient to exclude rare complications.