| Research Abstract |
The purpose of this study is to investigate effects of forced passive joint movement or joint immobilization on the experimental heterotopic ossification which is induced by bone morphogenetic protein implanted in murine quadriceps muscle. The crude bone morphogenetic protein was extracted from the bovine cortical bone as a fraction of 4M-GuHClsoluble, 0.5M-GuHCl insoluble and water insoluble. The total amount of protein powder weighed up to 1647mg after lyophilization. This protein showed active and stable new bone formation in murine muscle by implantation. Ten milligram of protein powder was implanted in murine quadriceps muscle and each mouse was devided into three groups. The first movement/immobilized group were imposed passive movement on the knee and the hip joint for 20 minutes with CPM machine and then immobilized from the hip through the ankle with plaster cast everyday. The second group was only immobilized as same. The third group was kept under free movement. Three weeks after implantation, the new bone formation was confirmed in all of murine thigh muscle with softex film. The new bone was sampled out and sintered at 1000℃. The ash weight was 2.95mg in the 1st group, 1.98mg in the 2nd, and 2.12mg in the 3rd. The 1st group showed higher bone formation than the other groups. Pathohistologically, myotube cells appeared around the protein powder at the early stage of implantation in each group, which seems to be dedifferentiation of surroundings mesenchymal tissue. Fourteen days of implantation, the 1st group tended to show small hemorrhage and vascular proliferation in the surrounding fibrous tissue compared with other groups. In the next, early phase (first 7days), intermediate phase (2nd 7days) and late phase (3rd 7days) of passive movement was applied on the movement /immobilized group, but there was no difference of new bone formation among these three groups.
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