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 6 mm 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.
Keywords: BMP-7; Masquelet; bisphosphonate; critical size defect; induced membrane.
© 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.