血管柄付同種骨移植の実験的研究 第２報 放射線学的検討

Abstract

To study the healing mechanism of vascularized bone allograft, we performed experimental studies on genetically defined rats.In this paper, we mainly report our experimental model for vascularized bone allograft transplantation, which applies to the reconstruction of large bone defects, excluding joints, using radiological assessment in evaluating the viability of bone graft in this experimental model.The model employed in this study, was a vascularized tibiofibula from one genetically defined rat transplanted in an orthotopic, same limb, although the knee joint was removed to another genetically defined rat.Under anesthesia, the right tibiofibula was isolated with the femoral vascular bundle of a donor rat. The femoral artery and vein were dissected free from the groin to the popliteal fossa, keeping the saphenous artery and vein intact. The musculature just around the tibiofibula was also kept intact, so as not to damage the main vascular bundles in the lower leg during dissection. The knee joint was disarticulated and the joint surface was completely removed. The distal diaphysis was transected just proximal to the tibiofibula synostosis.In the recipient rat, the right lower limb including the knee joint, approximately 20mm in length, was removed to prepare a recipient bed, keeping the surrouding soft tissue intact. Donor tibiofibula with its vascular bundle was transferred orthotopically. First, the bone was fixed to the recipient bone using an intramedullary Kirschner wire. Next, the graft femoral vessels were microsurgically anastomosed end-to-end to the host popliteal vessels individually.As a control, we also made a non-vascularized bone allograft model. Soft tissues including periosteum around the graft bone were removed and grafted in the same way as the vascularized bone allograft model.Cyclosporin A (10mg/kg/day) was used for immunosuppression of the allograft.For methods of postoperative assessment, we used soft X-ray and bone scintigraphy.A positive scintiscan within the first week following surgery indicated the viability of the bone allograft under immunosupression in vascularized bone allograft.Callus formation from bone allograft on the second to third postoperative week also indicated the viability of bone allograft under immunosupression in vascularized bone allograft.The healing process of vascularized bone allograft from the osteosynthesis could be observed as a model of a segmental massive bone graft.Vascularity of grafted bone and it's rejection can be monitored using bone scintigraphy and soft X-ray.For these reasons, the model presented in this study should be useful for experimental studies on vascularized bone allograft transplantation to study the healing mechanism of the segmental massive bone graft, excluding joints.