AN ULTRASTRUCTURE INVESTIGATION OF OSTEOPORO-SIS FRACTURE HEALING IN OVARIECTOMIZED RAT

AN ULTRASTRUCTURE INVESTIGATION OF OSTEOPORO-SIS FRACTURE HEALING IN OVARIECTOMIZED RAT

Objective To elucidate the influence of osteoporosis on the fracture healing in ovariectomized rat. Methods 24 females 8-month-old SD rats were divided randomly into two groups.12 were sham-operated(Sham)and 12 were bilaterally ovariectomized(OVX) 3 months later.The femoral fracture model were made in both groups,the healing process was observed by transmission electron microscopy(TEM) on d3,d7,d14,d21,d28,and d42 after making fracture in control groups(Sham) and the osteoporosis group(OVX).Results According to the TEM findings,the types of fracture healing cells,their ultrastructure changes and functional states were almost identical in both groups till d21 after making fracture.In OVX group,the calcified cartilage was not resorbed and replaced by new woven bone,a lot of necrosis chondrocytes were found being embedded in a calcified chondroid matrix on d28;after this period,osteoclastic bone resorption become severe gra-dually accompanied by osteocytic osteolysis during d28 to d42 of fracture healing. Conclusion Osteoporosis greatly affect the fracture healing in the later period of healing proess.It demonstrated as endochondral bone formation delayed and increased osteoclastic bone resorption which was made even more severed by osteocytic osteolysis during the period of bone callus remodelling.