RhBMP-2 Versus Iliac Crest Bone Graft for Lumbar Spine Fusion

Study Design. Prospective randomized controlled trial of rhBMP-2/ACS (Infuse bone graft) versus iliac crest bone graft (ICBG) for lumbar spine fusion in patients over 60 years of age. Objective. To report on clinical, radiographic, and economic outcomes, at 2-year follow-up, in patients treated by posterolateral lumbar fusion with rhBMP-2/ACS versus ICBG. Summary of Background Data. RhBMP-2/ACS is widely used off-label for posterolateral spinal fusion. Despite encouraging initial reports, outstanding issues include the need for evidence regarding safety and efficacy in an older population; and an assessment of cost-effectiveness. Methods. Patients over 60 years old were randomized to rhBMP-2/ACS (n = 50) or ICBG (n = 52). Oswestry Disability Index, Short Form-36, and numerical rating scales for back and leg pain were determined preoperatively and at 6, 12, and 24 months postoperatively. Fusion was evaluated by fine-cut computed tomography scan 2 years postoperatively by 3 reviewers. All in-patient and subsequent out-patient event costs were recorded by a dedicated hospital coder. Results. Two-year postoperative improvement in Oswestry Disability Index averaged 15.8 in the rhBMP-2/ACS group and 13.0 in the ICBG group. Mean improvement in Short Form-36 physical component score was 6.6 in the rhBMP-2/ACS group and 7.5 in the ICBG group. There were 20 complications in the ICBG group and 8 complications in the rhBMP-2/ACS group (P = 0.014). Sixteen ICBG and 10 rhBMP-2/ACS patients required additional treatment for persistent back or leg symptoms. Two rhBMP-2/ACS patients had revision procedures, 1 for nonunion. Eight patients in the ICBG group had revision procedures, 5 for nonunion. Mean fusion grade on computed tomography scan was significantly (P = 0.030) better in the rhBMP-2/ACS (4.3) compared with the ICBG group (3.8). Mean cost of the initial admission was $36,530 in the rhBMP-2/ACS group and $34,235 in the iliac crest bone graft (ICBG) group. Total cost of care over 2 years was $42,574 for the ICBG group and $40,131 for the rhBMP-2/ACS group. Conclusion. RhBMP-2/ACS is a viable ICBG replacement in older patients in terms of safety, clinical efficacy, and cost-effectiveness.