The Masquelet Induced Membrane Technique With BMP and a Synthetic Scaffold Can Heal a Rat Femoral Critical Size Defect

Long bone defects can be managed by the induced membrane technique together with autologous bone graft. However, graft harvest is associated with donor site morbidity. This study investigates if a tricalcium phosphate hydroxyapatite scaffold can be used alone or in combination with bone active drugs to improve healing. Sprague Dawley rats (n=40) were randomized into four groups. (A) scaffold, (B) BMP-7, (C) BMP-7+scaffold, and (D) BMP-7+scaffold+systemic bisphosphonate at 2 weeks. Locked femoral nailing was followed by 6mm segment removal and implantation of an epoxy spacer. At 4 weeks, the spacers were removed and the defects grafted. Eleven weeks later, the bones were explanted for evaluation with radiography, manual assessment, micro-CT, histology, and Fourier Transform Infrared spectroscopy (FTIR). Isolated scaffolds (A) did not heal any defects, whereas the other treatments led to healing in 7/10 (B), 10/10 (C), and 9/10 (D) rats. Group D had greater volume of highly mineralized bone (p<0.01) and higher bone volume fraction (p<0.01) compared to all other groups. A synthetic scaffold+BMP-7 combined with a bisphosphonate improved the callus properties in a rat femoral critical size defect, compared to both BMP-7 and scaffold alone or the two combined. (c) 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:488-495, 2015.