THE OSTEOINDUCTIVE PROPERTIES OF PARTIALLY DEMINERALIZED BONE-MATRIX

The objective of this study was to provide the experimental basis for the use of partially demineralised bone matrix (PDBM) in a hospital bo ne bank as an alternative to allogeneic bone. Thirty cortical defects 0.6 cm in diameter in the tibia of 18 merino sheep were filled with al logeneic and autogenic cancellous bone, PDBM, and the hydroxyapatite c eramics Pyrost and Bio-Oss. The extent of new bone formation was ascer tained by way of fluorescent-optical, microradiographical and histolog ical examination. While, after a period of 6 weeks, implantation of au togenic cancellous bone and PDBM resulted in the virtually complete br idging of the defect, the new bone formation following implantation of hydroxyapatite ceramics showed no significant difference from the con trols. The effect of different sterilisation techniques on the osteoin ductive properties of PDBM was examined in a similar way. The evaluati on of 44 cortical defects showed excellent new bone formation for PDBM sterilised with ethylene oxide, gamma irradiation and ethyl alcohol. In a third series, 5-cm-long diaphyseal defects in the left tibia of 2 5 merino sheep were stabilised by medullary nailing and filled with PD BM, varying in form and size. It was shown that transplantation of PDB M with a particle size of 750 mu m resulted in the bridging of the def ect within 20 weeks, while larger transplants were predominantly resor bed. The addition of small amounts of bone marrow enhanced new bone fo rmation significantly. We conclude that sterilised PDBM, which can eas ily be provided by hospital bone banks, represents an alternative to u ntreated allogeneic bone.