Journal of orthopaedic trauma
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A validated canine critical-sized segmental defect model was used to compare efficacy of volumetric ratios of recombinant human bone morphogenetic protein-2 (rhBMP-2)/absorbable collagen sponge (ACS) with cancellous allograft bone or biphasic calcium phosphate ceramic granules using radiographic, biomechanical, and histologic analyses. ⋯ In this study, efficacy of the treatment correlated with the ratio of rhBMP-2/ACS to allograft. As volume of rhBMP-2/ACS decreased below a 1:1 volume ratio, the overall efficacy decreased, thus indicating a potential limit to extending rhBMP-2/ACS past a 1:1 volumetric ratio in large segmental defects. Furthermore, ceramic was found to be a successful replacement for cancellous allograft bone at a 1:1 volumetric ratio. Clinical application using graft expanders or bone void fillers with rhBMP-2 should be used carefully and requires further investigation.