Less Is More! An Analysis of Postoperative Outcomes Comparing Low-Dose E. Coli-Derived rhBMP-2 and Mammalian rhBMP-2 in Lateral Lumbar Spinal Fusion Surgery

STUDY DESIGN: Retrospective clinical study. OBJECTIVE: Investigating the fusion effect and side effect profile between low-dose E.BMP-2 and mammalian rhBMP-2. SUMMARY OF BACKGROUND DATA: Recombinant human bone morphogenetic protein-2 (rhBMP-2) is widely used in anterior and lateral lumbar spinal fusion surgery to stimulate fusion. This study aims to evaluate the clinical and radiologic outcomes of 2 commercially available preparations of rhBMP-2, Chinese hamster ovarian cell-derived rhBMP-2 (CHO-rhBMP-2) and Escherichia coli-derived rhBMP2 (E.BMP-2). METHODS: Two groups of patients who underwent minimally invasive lumbar spinal interbody fusion surgery (between L1 and S1) with E.BMP2 and CHO-derived rhBMP-2 from 2018 to 2024 were included. Preoperative and postoperative clinical outcome scores and radiologic parameters were compared. Interval radiographs were done to assess fusion and complication rates. RESULTS: A total of 75 patients and 154 levels were involved. There was no significant difference in baseline characteristics between the 2 groups. The average dosage of rhBMP-2 was 0.50 mg per level in the E.BMP-2 group and 1.91 mg per level in the rhBMP-2 group. There was no significant difference in postoperative clinical outcome scores and segmental lordosis. Fusion rates on dynamic radiographs were 100% for both groups. Fusion rate on CT scan was 86.4% (n=19) in the E.BMP-2 group, whereas it was 78.3% (n=18) in the rhBMP-2 group. One patient from each group underwent revision surgery for symptomatic cage subsidence. CONCLUSIONS: This study demonstrates that low-dose E.BMP-2 use in lumbar spinal fusion surgery is not inferior to a traditionally available rhBMP-2. Comparable fusion rate with lower dose of bone graft further highlights its efficacy. Low-dose E.BMP-2 is thus a safe alternative osteo-inductive agent that can facilitate spinal fusion.