Complex Allogratf Bone Grafts For Large Segmental Bone Defect Repair

PurposesTo investigate the effect of free autologous periosteal and vascular endothelial growth factor compound with allogeneic bone on the treatment of rabbit radius defects.Materials and MethodsFive New Zealand white rabbits, weighing2.5-3kg, were sacrificed by ear vein air embolism. Bilateral ulnar bone were havested with segment length of about40mm, and then they were cut into3segments,each12mm. Except soft tissue and marrow, after surface-demineralized they were deep-frozen in-80℃for two weeks and unfrozen for future use.Another sixty New Zealand white rabbits, weighing is2.5-3kg, were anesthetized by sumianxin injection(0.15ml/kg), after removing the hair and disinfecing the bilateral arms, bone defect of1.2cm was wade in the bilateral middle radial shaft. Then the standby allogeneic bone was placed in the bone defects. Finally vascular endothelial growth factor and free autologous periosteal were applicated locally alone or in combination. The rabbits were divided into4Groups. Group1(control Group):allogeneic bone; Group2:bone allograft and free allograft periosteum compound; Group3:bone allograft and VEGF compound; Group4: allograft bone with VEGF and free autologous periosteal compound. The results were assessed by gross observation, X-ray observations, biomechanical analysis and histological observation(HE staining) after4weeksn8weeks、12weeks. Results1. gross observation:after4weeks、8weeks、12weeks,bone callus in bone defect of Group4is more obvieous than Group1,2and3. Group3is better than Group2and1, and Group2is better than Group1. After4and8weeks, callus of Group4was significantly more than1,2and3, and the new bones were found in the bone defect area.2. X-ray examination:X ray display after4and8weeks, Bony callus in Group4was more than Group1,2and3. Group3was better than Group1and2. There was only a small amount of new bone formation in bone defect in Group1. After4weeks, some soft tissue filled in it. Still a nonunion in8weeks,after12weeks both4Groups To be healed, callus bone defects are significantly more than the host bone, part of the medullary cavity is unobstructed. The radiographic score after statistical analysis display that after4weeks, the mean of radiographic healing score of Group4is higher than Group1,2,3; Group3is higher than Group1,2; Group2is higher than Group1(p<0.05); after8weeks, Group4is higher than Group1,2,3; Group3is higher than Group1,2; Group2is higher than Group1(p<0.05); after12weeks, The healing effect of Group4is best(p<0.05), followed by Group2and3(p>0.05); Group1is the last.3.histological examination:after4and12weeks, the preparation of bone mass in Group4is more than Group1,2,3, followed by Group2and3(p>0.05); Group1is the last one(p<0.05). After8weeks, Histological healing score increases gradually in the four Groups.4.Biomechanical testing:after four weeks, the three point bending stress of Group4is significant higher than Group1,2,3, followed by Group2and3(p<0.05); Group1is the las t(p<0.05); after8weeks, the three point bending stress of the4Groups Increases gradually; after12weeks, the four Groups have no significant difference.(p>0.05)Conclusion1.Both VEGF and free autologous periosteal play an important role in bone defect healing process.2. Local applicated exogenous VEGF and free autologous periosteal compound of allograft bone, can obviously promote the healing of bone defects, increase the callus formation. But the two composite application is more effective to the large segmental bone defect healling.