摘要
目的研究骨水泥假体柄与股骨界面应力传递的力学模型。方法将股骨、骨水泥,假体柄视为线弹性和各项同性材料结合的同心圆柱体。建立包含热效应时的轴对称界面应力传递模型,获得了股骨、骨水泥和假体柄轴向应力以及假体柄/骨水泥、骨水泥/股骨界面剪切应力随轴向位置的分布。结果界面失效是假体柄/骨水泥/股骨结构的主要失效形式,且存在热效应时,界面更可能产生混合的而不是存剪切的失效形式;由于骨水泥具有较高的热膨胀系数,热效应的存在具有加速界面失效从而加剧应力遮盖效应的趋势;在较高热残余温差下,运用钴铬合金比Ti-6Al-4V合金假体柄材料更容易导致界面和股骨的失效。结论在骨水泥,假体柄承受压缩应力的状态下,应用弹性力学的基本方程,获得了假体柄,骨水泥,股骨轴向应力以及界面剪切应力随轴向位置的分布。界面失效是假体柄,骨水泥,骨结构承载的主要失效形式。热残余温差的存在,加速了假体柄、骨水泥和股骨界面的失效,加速了假体柄的松动,加剧了股骨应力遮盖效应。这主要是骨水泥具有较高的热膨胀系数所致。由于Ti-6Al-4V(钛合金)材料的弹性模量和热膨胀系数比钴铬合金小,在一定程度上缓和了界面和股骨的失效。这与临床所见一致。
Objective To study the modeling stress transfer at the interface of cemented prosthesis and femur. Methods assuming that the prosthesis, the cement and the femur are concentric cylinders made of linear elastic and isotropic materials. The axisymmetrie interracial stress transfer model considering thermal effect is established, distribution of axial stress of the prosthesis, the cement and the femur, distribution of the interfacial shear stress at the prosthesis-cement interface and at the cement-femur interface in axial direction is obtained. Results Interracial failure is the main failure form of prosthesis-cement-femur structure under the external load. Under the effect of residual thermal stress,it＇ s more likely to produce the mixed failure form but not the pure shear failure form. Since the cement has a relatively high thermal expansion coefficient, the existence of thermal effect accelerates the interfacial failure and then aggravates the stress shielding effect. Under a relatively high thermal residual temperature difference, the cobaltchromium alloy prosthesis material is more likely to lead to the interfacial and femur failure than the Ti-6Al-4V alloy prosthesis material. Conclusion When the prosthesis bears the compress stress, assuming that the prosthesis, the cement and the femur are concentric cylinders made of linear elastic and isotropic material, by using the basic equations of axisymmetric elastic mechanics, the distribution of axial stress of the prosthesis, the cement and the femur, the interracial shear stress at the prosthesis-cement interface and at the cement-femur interface in axial direction were obtained. Interfacial failure is the main failure form of prosthesis-cement-femur structure under the external load. The existence of thermal residual temperature difference accelerates the failure and the destroy of the prosthesis-cement interface and the cement-femur interface, accelerates the relaxation of the prosthesis, aggravates stress shielding effect of the femur. The main reason for this is that the cement has a relatively high thermal expansion coefficient. The elastic modulus and the thermal expansion coefficient of Ti-6Al-4V material are smaller than that of cobalt-chromium alloy material. The existence of thermal effect decreases the efficiency of interfacial stress transfer, but to a certain degree it alleviates the failure of the interface and the femur,which is unanimous with the clinical findings.
出处
《透析与人工器官》
2009年第1期6-11,共6页
Chinese Journal of Dialysis and Artificial Organs
关键词
股骨
骨水泥假体柄
应力分析
femur
cemented prosthesis
interfacial stress analysis
