OBJECTIVETo investigate the mechanism of the repair of the necrotic tubular bone with pedicled vascular periosteum grafting in rabbits.

METHODSTwenty mature New Zealand rabbits aged 8 months were randomly divided into test and control groups by placebo-controlled protocol. A segment of radius measuring 1.2 cm in length with pedicled vascular periosteum of the rabbits in the test group was obtained from the middle distal part of the bone, and boiled for 30 minutes. The cooled bone was then re-grafted and wrapped with vascularized periosteum and immobilized, while those in the control group, no periosteal grafting was done. X-ray examinations of the bones were carried out at 2, 4, 6, 8 approximately 10 post operation weeks (POWs). Meanwhile 4-5 rabbits were sacrificed for the harvesting of the radius on both sides for histological examination.

RESULTSIt was revealed by X-ray and histological study that the periosteal hyperplasia could be observed 2-4 weeks after operation in the test group. The sign of union of the fracture and the formation and reconstitution of the trabeculae could be observed 6-8 weeks after operation. The reconstitution of reticulated bone, the formation of the lamellar bone and new haversian system could be observed during 8-10 POW. The structure of the new formed bones became more mature and the fracture healed at 12 POW. In contrast, there was no changes in the necrotic bones in the control group at 2 POW and no signs of fracture healing at 4-6 POW, and the defect of the bones could be observed at 8 POW. The necrotic bones were totally dissolved and absorbed, and the bone defects could be observed clearly filled with fibrotic tissues at 12 POW.

CONCLUSIONThe necrotic bones could be replaced by regeneration of new bone originated from the pedicled vascular periosteum, so that the necrotic tubular bones could be repaired. But the necrotic bones in the control group were eventually absorbed, resulting in bone defects.