RhBMP-2 Versus Iliac Crest Bone Graft for Lumbar Spine Fusion: a Randomized, Controlled Trial in Patients over Sixty Years of Age

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.