The efficacy of rhBMP-2 for posterolateral lumbar fusion in smokers.

Study Design: Retrospective review of prospectively collected data, as part of an IRB-approved, FDA-regulated, randomized, nonblinded IDE trial of rhBMP-2 matrix for lumbar spinal fusion.

Objectives: The purpose of this study is to examine the influence of smoking on fusion rate and outcome in a large series of patients treated with an rhBMP-2 matrix (AMPLIFY) or iliac crest bone graft as part of a randomized IDE trial for single-level lumbar fusion.

Summary Of Background Data: Preclinical studies suggest that bone morphogenetic proteins (BMPs) are able to reverse the negative influence of nicotine on fusion healing in animal models. It remains unclear if a similar benefit will be seen in humans, and if so, what formulation and amount of BMP will be required to achieve that improvement.

Methods: We reviewed the clinical and radiographic records of 148 patients who underwent single-level instrumented lumbar fusion at three spine centers as part of an ongoing FDA-regulated IDE trial. Clinical outcome measures included Oswestry Disability Index, SF-36, back, and leg pain scores. Radiographic measures were plain radiographs with flexion-extension views and fine cut computed tomography scans with sagittal and coronal reconstruction. Fusion success was determined by independent radiologist readings.

Results: At 2 years postoperatively, solid fusion was demonstrated in all 55 nonsmokers in the rhBMP-2 group (100%). Successful fusion was seen in 20 of 21 smokers in the rhBMP-2 group (95.2%). Fusion was achieved in 48 of 51 nonsmokers in the iliac crest bone graft (ICBG) group (94.1%), but only 16 of 21 smokers (76.2%) in the ICBG group.

Conclusions: The results of this study suggest that rhBMP-2 may enhance fusion rate in cigarette smokers undergoing single-level instrumented posterolateral lumbar fusion. Despite the improvement in fusion rate with rhBMP-2, clinical outcomes measures were still adversely affected in smokers.