新型骨质疏松大鼠骨生物力学测试方法：股骨干骺端弯曲试验

A novel biomechanical testing protocol for osteoporosis in rats： femur metaphysis bending test

目的建立一种新的骨生物力学测试方法用以评价去卵巢骨质疏松大鼠股骨干骺端生物力学的变化。方法20只5月龄雌性SD大鼠随机分为去卵巢组和假手术组。术后12周，对全部大鼠进行股骨骨密度和股骨远端骨组织计量学测定。所有大鼠取一侧股骨行中段三点弯曲试验，另一侧股骨行干骺端弯陆试验，测定生物力学指标（最大载荷、屈服载荷、刚度）。对各生物力学指标和骨密度及骨组织计量学指标行Pearson相关分析。结果去卵巢组股骨骨密度、骨组织计量学指标（骨小梁面积百分比、骨小梁数量、骨小梁厚度）和生物力学参数（最大载荷、屈服载荷、刚度）较假手术组均明显降低。在股骨干骺端弯曲试验中，两组最大载荷和屈服载荷的差值明显大于三点弯曲试验所得的相应差值。Pearson相关分析显示骨生物力学各参数与骨密度、骨组织计量学指标均呈正相关，且股骨干骺端弯曲试验的生物力学参数与骨密度、骨组织计量学指标的相关性明显强于股骨干三点弯曲试验。结论建立了新型骨质疏松大鼠骨生物力学测试方法，即股骨干骺端弯曲试验，可用来评估去卵巢骨质疏松大鼠股骨干骺端生物力学性能，与股骨干三点弯曲试验相比，其敏感度更高，与骨密度和骨组织计量学参数的相关性更强。

Objective To establish a new biomechanical test for evaluating biomechanical proper- ties of femoral metaphysis in ovariectomized rats. Methods Twenty-five-month-old female Sprague-Dawley rats were randomly divided into ovariectomized （OVX） group and the sham-operated （Sham） group （n=10）. Twelve weeks after operation, femur BMD and histomorphometry of distal femur were detected. Furthermore, femur biomechanical parameters were determined by diaphysis three-point bending test and a new designed metaphysis bending test. The relationships between the biomechanical parameters and BMD or bone histomorphometry were assessed with Pearson correlations. Results The femur BMD, bone histomorphometrical indexes （%Th.Ar, Tb.N,Tb.Th）, and biomechanical parameters （maximum load, yield load and stiffness） of OVX group significantly decreased compared with Sham group. In metaphysis bending test, the mean differ- ence of the maximum load （Fmax）, yield load （Fy） between group OVX and Sham were significant higher than that in diaphysis three-point bending test. Positive correlations between biomechanical parameters and femur BMD or bone histomorphometry indexes were observed in both the diaphysis bending and metaphysis bending test. The biomechanical parameters in the metaphysis bending test showed stronger correlations with BMD and bone. Conclusion Femur metaphysis bending test could be used to evaluate the biomechanical properties of osteoporosis. When compared with diaphysis bending test, femur metaphysis bending test is more sensitive in evaluating the change of biomechanical properties of femur in osteoporotic rats.