Prospective Randomized Outcomes Comparing rhBMP-2 to Autograft with Cortical Bone Dowels in Lumbar Spine Fusions

· (a - Medtronic Sofamor Danek)

PURPOSE:
In this study, we compared 24 month clinical and radiographic outcomes of recombinant human bone morphogenetic protein-2 (rhBMP-2) to those of iliac crest autograft when used with cortical allograft bone dowels in lumbar fusions.

MATERIALS AND METHODS:
All patients underwent single level, stand-alone anterior lumbar discectomy and interbody fusion (ALIF) procedures using threaded cortical allograft dowels (MD II Bone Dowels, Regeneration Technologies). Forty six patients from five investigational sites were randomized into two groups: 1) a control group receiving autogenous iliac crest bone graft, and 2) an rhBMP-2 group receiving rhBMP-2 on a collagen sponge carrier (InFUSE™ Bone Graft, Medtronic Sofamor Danek). Clinical outcomes were assessed using Oswestry disability, SF-36, neurologic status, work status and back and leg pain questionnaires. Interbody fusion was evaluated with plain radiographs and CT scans. RESULTS: The mean operative time in the rhBMP-2 group (108 minutes) was less than that for the control group (114 minutes). The average blood loss in the rhBMP-2 group was 124 ccs as compared to 245 ccs in the control group (p*=0.026). The average hospital stay was similar in both groups (3.4 days for rhBMP-2 vs. 3.7 days for control). At 6 months postoperatively, 90.5% of patients in the rhBMP-2 group showed evidence of interbody fusion as compared to 65.0% in the control group (p*=0.067). At 12 months, all patients (100%) in the rhBMP-2 group were fused as compared to 89.5% of control patients. The mean Oswestry disability scores revealed marked improvement from preoperative values through 24 months for both study groups. However, the rhBMP-2 group consistently realized more rapid clinical improvement postoperatively. While there was no iliac crest donor site pain in the rhBMP-2 group, evidence of this pain persisted in approximately 40% of patients in the control (autograft) group at 24 months.

CONCLUSION:
Results of this study reveal several improvements in ALIF procedures with bone dowels provided by the use of rhBMP-2 as a replacement for iliac crest autograft. Trends in average OR time, blood loss, and hospital stay demonstrate improved surgical and hospital efficiencies. Postoperatively, patients receiving rhBMP-2 showed improved clinical and radiographic outcomes.