Instrumented One and Two Level Posterolateral Fusions With Recombinant Human Bone Morphogenetic Protein-2 and Allograft: A Computed Tomography Study

Prospective analysis of patients fused with freeze-dried corticancellous allograft, local bone graft, and recombinant human bone morphogenetic protein (rhBMP-2) (Infuse) studied for a minimum follow-up of 24 months. To assess the fusion rates of the allograft and Infuse using plain radiographs and reconstructed computed tomography (CT) scans. Outcome measures included Oswestry Disability Index, Verbal Rating Pain Scale for back and leg pain, and SF-36 Health Survey as well as complications. The "gold standard" for arthrodesis of the lumbar spine includes the use of autogenous iliac crest bone graft. Morbidity associated with this harvest is well established. Alternatives to autogenous iliac crest bone graft harvest are being sought both to improve and match arthrodesis rate and secondarily to decrease donor site morbidity. A prospective consecutive series of 36 patients treated for lumbar acquired spinal stenosis and degenerative disc disease leading to instrumented 1 and 2 level fusions were studied. These patients were arthrodesed with rhBMP-2 and freeze-dried corticancellous allograft and limited amounts of local autogenous bone graft. Fusion by reconstructed coronal and saggittal CT analysis occurred in 97.2% of the cases. The Oswestry Disability Index, Verbal Rating Pain Scale, and SF-36 Health Survey were statistically improved (P < 0.05) from preoperative to final postoperative values. Complications were limited and unrelated to rhBMP-2 and the absorbable collagen sponge. rhBMP-2 (Infuse) at a dose of 12 mg/1.5 mg/mL combined with freeze-dried corticancellous allograft and local autogenous spinous process and lamina bone resulted in new bone formation (fusion) as determined by CT scan. In this preliminary study, fusion rates were 97.2% with consistent posterolateral bone formation. Outcomes and complications are consistent with other studies of this type.