Experimental Study On Bone Defect Repairment In Rabbit Radius With Antigen-extracted Xenogenic Cancellous Bone Combined With Vascularized Periosteal Flap

Objective: The purpose of this study was to investigate the efficacy of bone defect repairment in the rabbit radius with antigen-extracted xenogenic cancellous bone combined with vascularized periosteal flap.Materials and Methods: One and a half centimeters long defects were modeled in the bilateral radialis midpiece of 60 Zelanian rabbits. One side defects of the 30 animals were Group A implanting with antigen-extracted xenogenic cancellous bone combined with vascularized periosteal flaps and the other side defects were Group B simply implanting with antigen-extracted xenogenic cancellous bone. One side defects of the left30 animals were Group C simply implanting with the vascularized periosteal flaps while neither the vascularized periosteal flaps nor the antigen-extracted xenogenic cancellous bone was implanted in the other side defects of Group D. Following surgery, before the 60 animals were sacrificed by air embolism in groups of 20 after 4, 10, and 16 weeks,respectively, anteroposterior radiographs were taken. Specimens harvested from the tissue of defects after macroscopic observation at different time stages were sectioned at 0.5 cm and stained using Hematoxylin-Eosin for microscopic observation and biomechanical test was performed for the four groups. Radiological scores and histological scores were got according to Lane-Sandhu’s X-ray grading standard and Lane-Sandhu’s histological grading standard. The averages of radiological scores, histological scores and the maximum pressure load/displacement ratios between Group A and Group B, Group A and Group C, Group A and Group D were compared with paired t tests and 0.05 was the significance level.Results: The macroscopic observation, radiological examination and microscopic histological observation after 4, 10, and 16 weeks following surgery showed the osteogenesis, remodeling of new bone and degradation of antigen-extracted xenogenic cancellous bone in Group A was better than that in Group B. The radiological scores and histological scores were significantly higher in Group A than those in Group B after 4, 10,and 16 weeks following surgery(P<0.05). Biomechanical test showed that the maximum pressure load/displacement ratios in Group A were significantly higher than those in Group B after 4, 10, and 16 weeks following surgery(P<0.05). Specimens were not harvested from the tissue of defects as well as radiological scores were not performed in Group C and Group D because the radiological examination and macroscopic observation of the bonedefect areas in them presented filling by fibrous tissue, no new bone formation and absorption of bone ends at 4 weeks after surgery, filling by scar tissue,little callus formation and atrophy of bone ends at 10 weeks after surgery, filling by scar tissue,cone-shaped osteogenesis, closed medullary cavity, sacralization with ulna and nonunion of bone ends at 16 weeks after surgery.Conclusions: This study demonstrated the efficacy of bone defect repairment in the rabbit radius with antigen-extracted xenogenic cancellous bone combined with vascularized periosteal flap was superior to repairment simply with antigen-extracted xenogenic cancellous bone and the new bone had better biological structure and function.