Recombinant Bone Morphogenetic Protein-2 (rhBMP-2) in High-Risk Ankle and Hindfoot Fusions

Abstract

Background: The purpose of this study was to evaluate the effect of rhBMP-2 on bone healing in patients who undergo high-risk ankle & hindfoot fusions. Materials & Methods: Patients who underwent high-risk, elective ankle and hindfoot fusions treated with rhBMP-2 augmentation were reviewed for clinical outcomes and complications. A total of 112 fusion sites (69 patients) were reviewed for analysis. The mean age of the patients was 52 years (range, 21 to 84 years). There were 37 males (53%) and 32 females (47%). Forty-four patients (64%) were smokers and 13 patients (19%) were diabetic. A history of high-energy trauma was present in 47 (68%) patients and avascular necrosis of the talus was present in 22 patients (32%). Forty-five patients (65%) had multiple risk-factors. The exclusion criteria were peripheral vascular disease, infection, and patients who were not available for the usual follow-up protocol. Internal and/or external fixation was utilized for ankle and hindfoot fusions. Bone graft was used only for patients who had defects or malalignment. Postoperatively, nonweightbearing radiographs were taken every 2 to 4 weeks (3 views per site). When plain radiographic union was evident, a confirmatory CT scan was obtained. Results: Overall, 108 fusion sites went on to union (96% union rate) at a mean time of 11 weeks (as assessed by a CT scan) [ankle joint at 10 weeks; subtalar joint at 12.3 weeks; talonavicular joint at 12.7 weeks and calcaneocuboid joint at 10.9 weeks]. Different union times between ankle, subtalar, talonavicular, and calcaneocuboid joint were not significant ( p = 0.2571, Kruskal-Wallis Test Nonparametric ANOVA). All sites: [No graft] vs. [Autograft] vs. [Allograft]: p = 0.2421 (Kruskal-Wallis Test Nonparametric ANOVA), were not statistically significant. Complications included nonunion in 5 of 112 joints in 3 patients (4% joint nonunion rate; 4% patient nonunion rate) [subtalar joint, n = 2; talonavicular joint, n = 1; and calcaneocuboid joint, n = 1]. Two patients had wound complications and one other patient had a deep infection; all were successfully treated with local wound care, negative-pressure dressings and antibiotics. Conclusion: We believe rhBMP-2 is an effective adjunct for bone healing in patients who undergo high-risk ankle and hindfoot fusions. Low complication rates were observed in this study. Level of Evidence: IV, Retrospective Case Series