The effect of ovariectomy on microarchitecture,bone mineral density,and bone biomechanics of the cortical bone in rats

Objective To observe the effect of ovariectomy on bone mineral density(BMD),bone microarchitecture,and biomechanics of the femur cortical bone in rats using micro-computed tomography and 4-point bending test.Methods Twenty-four 7-month-old SD female rats were randomly divided into ovariectomized(OVX) group and sham-operated(Sham) group.After 3 and 15 weeks,6 rats of each group were killed and the middle part of left femurs was scanned using micro-CT.The right femurs were performed with 4-point bending test.Results From 3 to 15 weeks after the surgery,the inner perimeter,outer perimeter,cortical bone area,the medullary cavity area,total area,bone mineral density,maximum load,elastic modulus,and breaking strength of the rats in OVX group had no significant difference compared to those in the Sham group(P0.05).The elastic modulus of rats in the OVX group on 15 weeks after the surgery was 36% lower than that on 3 weeks(P0.05).Conclusion The micro-architecture,bone mineral density,and biomechanics of cortical bone of the middle shaft of the femur have no significant change in rats 15 weeks after ovarietomy.But the bone biomechanics decrease fast in rats of OVX group.