股骨下端松质骨横向与纵向应力松弛特性

Horizontal and vertical stress relaxation characteristics of the distal femoral cancellous bone

背景:以往的研究多以一个标本加工成二个或多个试样进行实验,且标本多以纵向取样进行应力松弛实验。目的:比较股骨下端松质骨横向和纵向取样的拉伸应力松弛特性,为临床提供股骨下端松质骨的生物力学参数。方法:正常国人男性尸体股骨标本10个,左右侧各5个,年龄20～30岁,死亡后1h内解剖尸体取出左、右侧股骨,以生理盐水浸湿的沙布包裹标本,置于-20℃冰箱内保存。实验前取出标本,在常温下解冻,每个标本加工成长20mm,宽20mm,高20mm的试样。先对10个试样进行纵向应力松弛实验,之后待试样恢复24h后再对10个标本进行横向应力松弛实验。应力松弛实验的应变增加速度为0.5%/s,设定实验时间为7200s,采集100个实验数据。结果与结论:股骨下端松质骨纵向试样7200s应力松弛量为0.58MPa,横向试样7200s应力松弛量为0.72MPa。应力松弛曲线是以对数关系变化的。股骨下端松质骨横向7200s应力松弛量大于纵向。结果可以看出三参数模型建立的股骨下端松质骨的应力松弛方程能很好的反映股骨下端松质骨的应力松弛特性。

BACKGROUND：Previous studies mostly have two or more samples for experiments,and the longitudinal stress relaxation experiments are preferred.OBJECTIVE：To compare the horizontal and vertical tensile stress relaxation of the distal femoral cancellous bone,and to provide the biomechanical parameters of the distal femoral cancellous bone.METHODS：Ten femur samples from normal male corpses,aged 20-30 years,were selected,5 for each side.The femoral samples were taken out from the corpses within 1 hour after autopsy.The right femoral samples were covered with saline-soaked gauze,saved in-20 ℃ refrigerator.Before experiment,the samples were taken to be thawed in room temperature and made into specimens of 20 mm×20 mm×20 mm.Firstly,longitudinal stress relaxation experiments were performed in 10 specimens,and 24 hours later,horizontal stress relaxation experiments were performed in these 10 specimens.Strain acceleration was 0.5%/s,experimental time was set to 7 200 s,and 100 experimental data were collected.RESULTS AND CONCLUSION：The longitudinal and horizontal stress relaxation was 0.58 MPa and 0.72 MPa at 7 200 s,respectively.The stress relaxation curve changed based on the relation of logarithm.The longitudinal creep strain at 7 200 s was lower than the horizontal one.The stress relaxation equation of the distal femur cancellous bone based on the three-parameter model can well reflect the stress relaxation properties of the distal femur cancellous bone.