防腐与PMMA人工股骨近端标本的轴向生物力学差异

目的比较防腐与聚甲基丙烯酸甲酯（PMMA）人工股骨标本之间的生物力学特性的差异。方法选择单足站立位受力模型,在Instron-8874液压伺服力学实验测试机上对各标本（防腐与PMMA人工股骨）行预加载处理5次,消除股骨松弛、蠕变等时间效应影响后,开始对各标本进行正式实验,每个标本测试5次,各次测试之间应间隔20min,待应变仪上的数值变化小于3με时再记录数据。施加在模型上的总载荷为1200N,以100N分级增量方式加载,实验机压头下降速度为10mm/min。观察防腐与PMMA人工股骨标本近端的载荷-应变关系、股骨头的载荷-位移关系和股骨头的轴向刚度。结果防腐与PM-MA人工股骨标本在2倍于人体体质量的载荷下的载荷-应变关系都基本呈线性变化;在载荷为1200N时,PMMA人工股骨标本的位移明显大于防腐股骨标本的位移（P〈0.01）;防腐股骨标本的轴向刚度大于PMMA人工股骨标本（P〈0.01）。结论在进行轴向生物力学实验研究中,往往需要大量的股骨标本,在股骨标本获得日益困难的情况下,PMMA人工股骨标本在一定程度上可以替代防腐股骨标本进行轴向生物力学研究。

Axial biomechanical difference between embalmed and PMMA proximal femur

Objective To compare the biomechanical difference between embalmed and poly （methyl） methacrylate（PMMA） femur. Methods The mechanic force model of single -foot standing was selected, and the Instron -8874 hydraulic servo mechanical testing machine tested specimens （embalmed and PMMA femur） were preloaded on 5 times. The specimen tests were started after eliminated the time effects of relaxation and creep, each specimen tested 5 times, every test should be set at an interval of 20 minutes, recorded data when changing the values of strain gauge was less than 3 με. Under the total loading of 1 200 N, with 100 N multi-step incremental cycling loading, the speed of testing machine was controlled 10 mm/min. The relation between load and strain, load- displacement and axial direction rigidity of femur head were observed. Results The load exhibited linear change with strain under 2 times of body weight loading in embalmed and artificial specimens;The displacement of artificial specimens was greater than that in embalmed specimens（P 0.01）, but the axial rigidity of embalmed femur specimens was larger than that in artificial femur specimens（P 0.01）. Conclusion Experimental study on the biomechanics often requires a lot of femoral specimens,but difficulty of obtaining fresh femur specimens is increasing, thus PMMA femur specimens can replace the embalmed femur specimens to a certain degree in biomechanics experiment.