αBSM failed as a carrier of rhBMP-2 to enhance bone consolidation in a sheep model of distraction osteogenesis

Purpose: One of the problems associated with callus distraction is a long time period needed for consolidation of the newly formed bone. The goal of this study was to determine whether percutaneous injections of rhBMP 2 in alpha BSM would enhance bone consolidation. Methods: A unilateral tibial osteotomy combined with external stabilization was performed in 20 adult sheep. After a latency of four days, distraction was conducted for 20 days. Sheep were divided into three groups: group 1 received rhBMP-2/alpha BSM injections at day 23 and 30, group 2 buffer/alpha BSM injections at day 23 and 30 and group 3 did not receive any injection. The radiographs and in-vivo torsional stiffness measurements were obtained weekly during the following 50 days. Post-mortem bone densitometry (DXA) and mechanical testing were performed. Results: In-vivo stiffness assessments, DXA values and the maximum torsional moment of the sheep tibia treated with two rhBMP-2 injections were not significantly greater than those of both control groups. Conclusions: Presented application of rhBMP-2 in alpha BSM failed to enhance bone consolidation in distraction osteogenesis.