Repair of Large Segmental Bone Defect using Vascularized Small Corticocancellous Bone in Rabbit Femur

Background Although free-vascularized long-bone transfer is useful for reconstruction of a large segmental bone defect, it is limited by availability of transplantable bone, meticulous microsurgical technique, and donor-site morbidities. Hence, easier, readily available, and safer surgical procedures are warranted. This study evaluated the effects of vascularized small corticocancellous bone grafting for reconstruction of a large segmental rabbit femur defect. Methods A 1.5 cm defect was created in the femurs of 40 New Zealand white rabbits and divided into a control group (n = 10, bone defect without graft), group A (n = 10, bone defect filled with morselized autogenous bone), group B (n = 10, bone defect grafted with a vascularized small corticocancellous bone and morselized autogenous bone), and group C (n = 10, bone defect grafted with a vascularized small corticocancellous bone). Simple radiographs were taken postoperatively, and bone healing ability was scored using Taira's radiologic scale. Histologic examinations were scored using Emery's histologic scale. The expression of osteogenesis-related growth factors (BMP-2, -4, and -7, VEGF, and RANKL) was analyzed. Results Radiologically, group B showed superior biological efficacy in bone formation and consolidation over the other groups. Histologically, the defect in group B was filled with more abundant mature bone than the other groups. Group B showed higher gene expression of BMP-2, -4, and -7, and VEGF. Conclusions The grafting of the morselized autogenous bone (MSB) combined with the vascularized small corticocancellous bone is more effective than that of the MSB alone for repairing a large segmental bone defect.