Recombinant human BMP-2 increases the incidence and rate of healing in complex ankle arthrodesis

Abstract

Background: Although its FDA-approved applications are limited, the pro-osteogenic benefits of recombinant human BMP-2 (rhBMP-2) administration have been shown in off-label surgical applications. However, the effects of rhBMP-2 on ankle fusions are insufficiently addressed in the literature, which fails to include a case-control study of adequate sample size to evaluate the efficacy of rhBMP-2 treatment. Questions/purposes: In this study we asked whether rhBMP-2 treatment (1) would increase the rate of successful ankle fusion in complex patients (patients with comorbidities associated with poor surgical healing) compared with a control group of patients undergoing ankle fusion who did not receive rhBMP-2; (2) would reduce total time wearing a frame when compared with the control group; (3) would result in a difference in the percentage of bone bridging between the group treated with rhBMP-2 and the control group, as determined by CT scans 3 months after surgery; and (4) would encounter an equal rate of complications different from untreated patients. Methods: A retrospective chart study was performed on 82 patients who, because of a host of comorbidities associated with poor healing, required a complex ankle arthrodesis with the Ilizarov technique. The first 40 patients did not receive rhBMP-2, whereas the subsequent 42 patients received intraoperative rhBMP-2. Time wearing the frame was determined by chart review; decision to remove the frame was made by the surgeon based on quantitative bone bridging measured using a CT scan taken 3 months after fusion. Results: Patients treated with rhBMP-2 were more likely to obtain fusion after the initial surgery (93% versus 53%, p < 0.001; OR, 11.76; 95% CI, 3.12-44.41), spent less total time wearing the frame (124 versus 161 days, p < 0.01), and showed more bone bridging on CT scans (48% versus 32%, p < 0.05). All patients with greater than 30% bone bridging observed on CT scans 3 months postoperatively achieved successful union without further intervention. Conclusions: Our findings suggest that rhBMP-2 is a beneficial adjunct for selected groups of patients undergoing complex ankle arthrodesis. CT is a promising modality in the assessment of bone healing in ankle fusion. A proper randomized controlled trial remains necessary to fully describe the efficacy of rhBMP-2 in accelerating bone healing. Level of Evidence: Level III, therapeutic study. See the Instructions for Authors for a complete description of levels of evidence. © 2013 The Association of Bone and Joint Surgeons®.