生物力学因素对大鼠激素性股骨头坏死的作用

Role of Biomechanics in Femoral Head Necrosis

目的:通过对使用激素后不同时段大鼠股骨头生物力学性质的测定,探究激素性股骨头坏死的发病机理。方法:4月龄健康Wistar大鼠随机分成实验组与对照组造模,实验组形成股骨头坏死超负重模型,对照组生理状态下正常负重。分别于2、4、6、8周处死,取右侧股骨头标本,于EnduraTEC ELF3200生物力学材料动态力学性能测试系统行压力测定,计算样本纵向最大位移、刚度、压缩过程能量吸收等生物力学参数。结果:实验组中各个时期股骨头骨小梁宽度、刚度低于同期对照组,最大形变、压缩能量吸收均高于同期对照组(P<0.05),随超负重时间延长,骨质疏松程度增加。结论:随着激素注射和超负重时间的延长,骨质疏松、骨细胞凋亡明显;在激素条件下,负重增加骨小梁的断裂,降低股骨头的生物力学性质,成为引起激素性股骨头坏死塌陷的直接外部因素。

Objective To study the etiology of the glucocorticoid induced necrosis of the femoral head through observation of the characteristics of biomechanics. Methods Forty healthy 4-month Wistar rats were divided into two groups randomLy, 20 in models and 20 in control. After the buttock injection of dexamethasone 20mg/kg weakly for 8 weeks, the model group was established to run on the running machine at a speed of 1 km/ h for 30 minutes twice a week, forming the hyper-weight model, and at the same time, the control group was not, only with the physiological weight. Both groups were killed at a time interval of 2 w, 4 w, 6 w and 8 w. The left legs were taken for biomechanics teat on the EnduraTEC ELF 3 200, to make the deflection-load curve with Origin 7.0, and the stiffness was calculated and analyzed. The right legs were made into sections for the HE coloration. Results At different time intervals the width and stiffness of bone trabeculae in the model group were lower than those in the control on the stiffness, but higher on the deflection and energy absorbed. Osteoporosis was also getting severe. Conclusion In the model of glucocorticoid-induced osteonecrosis of the femoral head, osteoporosis, necrosis of the osteocyte and cartilage, and rebuilding of the cartilage got significant, with the usage of the glucocorticoid and the prolonging of the hyper-weight time; with the effect of the glucocorticoid, weight can increase the breaking down of the trabeculae, decrease the biomechanical characteristics, which can be considered as direct reason of the necrosis of the femoral head.