Biological Study Of Bone Healing Of Canine Iliopectineal Crest At Persistent Osteogenic-promoting Stress

Objectives:To explore the characteristic and mechanism of bone healing of canine iliopectineal crest at persistent osteogenic-promoting stress. Methods:Animal models of 25 adult mixed breed dogs were established by transverse osteotomy at bilateral iliopectineal crest,which were fixed with ATMFS anterior column connector and steel plate respectively. The animals were examined at 2,4,6,8,and 12 weeks by X-ray,macropathological observation and biomechanical test. Tetracin fluorescent labeling,HE staining,Masson triad colour staining,in situ hybridization and immunohistochemical method were performed and histological image analysis were applied. Osteocalcin and Cbfαl mRNA expression were examined by RT-PCR. Results:Mechanical property of ATMFS side was superior to steel plate side and there was significant difference of the rates of bone porosity and integrated optical density(IOD)of new bone formation after 4 weeks. The alinement of collagen typeⅠand osteoblast was consistent with the orientation of cortical bone,trabecular bone and stress. Image analysis showed IOD of tetracycline fluorescence labeling and expression of osteocalcin and bone sialoprotein had significant deviation at 4-8 weeks. There was significant difference of collagen typeⅠat 6-12 weeks. According to result of RT-PCR,the expression of Cbfα1 and osteocalcin mRNA was different significantly at 4-6 and 4-8. Conclusion:Anatomical fixation and persistent osteogenic stress can stimulate earlier bone healing. This is closely correlated with early differentiation of osteoblast and synthesis of collagen along the line of stress.