人密质骨动态力学性能及莫电效应

THE DYNAMIC MECHANICAL PROPERTIES ANDSTRAIN-GENERATED POTENTIALS OFHUMAN CORTICAL BONE

本实验建立起用Ｈｏｐｋｉｎｓｏｎ压杆技术，测量骨动态力学性能及骨应变源电动势的实验方法，对新鲜人股骨密质进行测试。①低应变率下（２ｘ１０－３／ｓ）骨弹性模量值为１３．６ＧＰａ，与高应变率（６ｘ１０２／ｓ）下骨弹性模量值１８．３ＧＰａ之间差别显著，表明骨是一种粘弹性材料。②结合骨断面扫描电镜图象，讨论了静、动载荷下骨创伤发生的机制，证实骨单位粘合线处是密质骨力学性能薄弱点，骨单位断裂前发生骨板相对滑动。③湿骨试件应变源电动势（ＳＧＰｓ）峰值较干骨试件大，且时相滞后于骨应变时相约４４μｓ，干骨试件ＳＧＰｓ无明显滞后。④提出压电效应和流动电动势分别是干、湿骨试件ＳＧＰｓ产生的机制。实验结果为新型骨生物材料研制，临床骨伤病电刺激疗法的应用，以及骨折愈合质量的评价等，提供了理论依据。

Dynamic mechanical properties and strain-generated potentials( SGPs ) of human femoral bone specimens were measured with splitHopkinson bar technique. Strain gauges ( EX-220-1AA ) and silver el-ectrodes of size 2mm were placed at the mid-section of thespecimens. The data acquisition system, a personal computer with atransient A/D converter, collects data points in a rate of two to fivetimes per microsecond. Each specimen was tested under stepwise-incr-eased jmpact load until fail. All the data collection and reductionwere performed by computers or computer controlled equipments. Thestatic mechanical properties were also measured in an Instron 1186testing machine, for comparing with the dynamic ones. The surfacemorphological structure at fracture site was obser ed.The Young's elastic modulus of fresh human cortical bones chan-ged significantly from 13.6GPa to 18.3GPa for low and high strainrates. The osseous lamellae of Haversion canal slid by each other un-der impact load and break along the cementing line. The time delayof SGPs vs. the strain was about 440 s in fresh cortical bone, and notime delay in dry one. The peak value of-SGP changes due to theimpack speed might reach a maximum Value of-1000mV in fresh bonespecimens and 350mV in dry one before fail. We concluded that SGPsin fresh and dry cortical bones were generated by two different mech-anisms of piezoelectric effect and streaming potential.