[Osteoinduction with the dog tibial defect model]

The objectives of this study were to investigate the osteoinductive effect of demineralized bone matrix powder and of cancellous bone in a comparative experiment in a standardized dog defect model. 16 adult shepard dogs were divided into two test subgroups. One group underwent application of demineralized bone matrix (DBM) into the defect. The second group had their defects treated with autogenous cancellous bone (ACG) only. The progress of bone formation was observed for twelve weeks. The excised tibiae were examined by correlating serial X-rays with histologic sections stained with Giemsa and fluorescent labels. In this experiment no osteoinductive effect of demineralized bone powder could be demonstrated. The amount and localisation of bone regeneration in the matrix group seemed to be spontaneous, corresponding to the radiological and histological parameters. In the group of cancellous bone grafts, the defect (length 30 mm) was bridged by incorporation of the graft and graft mediated bone formation within twelve weeks. Disturbing factors such as instability, infection, insufficient vascularity, and cellular immune response to the graft were excluded in this model. The failure of the osteoinductive implants in our experiment compared with the good results obtained in rodents limits their value also in clinical situations. As long as there is no explanation for this failure, this technique should not be used in a clinical situation.