Comparable Fusion Response, but Increased Inflammatory Response, with Escherichia coli-Derived Recombinant Human Bone...

Background/Objectives: This retrospective study aimed to evaluate the radiologic outcomes and changes in biochemical inflammatory markers following posterior lumbar interbody fusion (PLIF) with Escherichia coli-derived recombinant human bone morphogenetic protein-2 (E.BMP-2), compared with conventional autologous bone grafting. Methods: The study included 112 patients undergoing single- or two-level PLIF for degenerative lumbar disease between 2022 and 2023, divided into E.BMP-2 (n = 50) and Control (n = 62) groups. Radiological outcomes, including Bridwell grading system and adjacent vertebral body (VB) changes, and changes in biochemical inflammatory markers-white blood cell (WBC) count, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and neutrophil count-were assessed. Clinical outcomes were also evaluated. Multivariate regression and propensity-score-matched analyses, and linear mixed-effects models were applied. Results: Fusion rates were comparable between the groups (90.8% vs. 96.7%; p = 0.466); adjusted analyses showed no independent association between E.BMP-2 use and fusion outcomes. The E.BMP-2 group demonstrated a higher prevalence of adjacent VB changes (78.5% vs. 54.3%; p = 0.001), and higher postoperative inflammatory markers including CRP levels on postoperative day 7 and at 1 month, along with increased neutrophil levels on postoperative day 4 (CRP day 7: 31.7 ± 26.4 mg/L vs. 18.7 ± 14.4 mg/L, p = 0.014; CRP 1 month: 7.2 ± 13.0 mg/L vs. 2.7 ± 3.8 mg/L, p = 0.022; neutrophil count day 4: 64.4 ± 10.6% vs. 60.6 ± 8.7%, p = 0.039). However, no significant differences in clinical outcomes, as assessed by VAS scores, were observed according to adjacent VB changes or inflammatory markers. Postoperative fever and infection rates were similar between groups. Conclusions: E.BMP-2 use in PLIF demonstrated fusion rates comparable to those of autografts, without demonstrated superiority. No significant differences in clinical outcomes were identified. Further large-scale prospective studies are needed to clarify its clinical role and optimal dosing.