Efficacy of two different demineralised bone matrix grafts to promote bone healing in a critical-size-defect: a radiological, histological and histomorphometric study in rat femurs

Abstract

The aim of the study was to compare two different demineralised bone matrices used clinically regarding their ability to induce bone healing in a critical-size-defect rat model. We stabilised 4 mm femur defects with a custom-made plate and filled them either with demineralised bone matrix (DBM) or DBX (DBX Putty®). Bone morphogenetic protein 2 (BMP-2)-loaded collagen and an empty defect served as controls. The outcome was followed after 21 and 42 days by radiology (Faxitron; microCT) and histology. Defect healing did not occur in any animal from the empty control, DBM or DBX group. Residuals of the implanted material were still found after six weeks, but only limited callus formation was visible. In contrast, the BMP-2 control demonstrated enhanced formation of callus tissue and undisturbed healing. After 21 days, 11 out of 16 and after 42 days, 7 out of 8 BMP-2-treated animals showed complete defect bridging by cancellous bone tissue. Demineralised bone grafts were not capable of defect reconstruction; only BMP-2 was able to provide sufficient stimulus to induce uneventful bridging under the specific experimental conditions.