BRIDGING OF LARGE DIAPHYSEAL BONE DEFECTS BY PARTIALLY DEMINERALIZED BONE-MATRIX

The problems arising from the transplantation of autogenic and allogen ic bone have significantly limited the use of these methods. Hence, th ere is an ever increasing demand for suitable transplant materials tha t could be readily available to orthopaedic surgeons throughout the co untry. Although the advantages of demineralized bone matrix over allog enic cancellous bone have been shown in numerous experimental studies, its broad clinical application has so far been limited. The purpose o f this study was to investigate the osteogenic properties of partially demineralized bone matrix in clinically relevant and realistic condit ions. Tibial defects 5 cm in length in 24 merino sheep were bridged by way of medullary nailing and filled with various preparations of bone matrix. Cortical bone displaying poor vascularization and rotation in stability of the osteosynthesis ensured extremely difficult testing co nditions for the transplant. Postoperatively, the extent of new bone f ormation was evaluated by means of regular X-ray examinations over a p eriod of 12-20 weeks. In addition, histological, fluorescent-optical a nd microradiographic examinations of the final specimen were carried o ut. Good new bone formation regularly followed the transplantation of partially demineralized bone matrix with a particle size of 750 mum. C omplete bridging of the defect was achieved when small amounts of bone marrow were added. The use of bone matrix with a smaller or larger pa rticle size did not influence the rate of new bone formation perceptib ly.