Rubin P J, Rakotomanana R L, Leyvraz P F, Zysset P K, Curnier A, Heegaard J H
DP-LGM Ecole Polytechnique Fédérale de Lausanne, Ecublens, Switzerland.
J Biomech. 1993 Jun;26(6):725-39. doi: 10.1016/0021-9290(93)90035-d.
A numerical model of a femoral total hip component based on the finite element method is developed to evaluate the relative micromotions at the bone-implant interface and the stress distribution in the femoral bone. The interface is modelled as unilateral contact involving Coulomb's dry friction between the bone and the implant. In addition, the model includes inhomogeneity, anisotropy as well as plasticity of both cortical and spongious bones. An automatic data processor coupled to a three-dimensional mesh generator is designed to extract cortical bone geometry and inhomogeneous distribution of trabecular bone density from data obtained with quantitative computed tomography (QCT). A preliminary application is conducted to evaluate the mechanical behaviour of an existing bone-prosthesis structure for two typical loadings: a load simulating the single leg stance and a load simulating the stair climbing stance. The obtained results are subdivided in two parts. Firstly, the characterization of stress transfer and micromotions at the bone-stem interface. The peak value of the shear micromotions reaches 600 microns in the proximal medial region with a friction coefficient equal to 0.6. An analysis of the influence of the friction coefficient reveals that the shear and distractive micromotions as well as the shear and normal stresses depend strongly on this coefficient. Secondly, the representation of stresses in the femoral bone. Determination of complementary invariants such as the hydrostatic pressure, the deviatoric stress and anisotropic stresses brings additional insights in the evaluation of the stress field in the femoral bone.
基于有限元方法开发了一种股骨全髋关节组件的数值模型，以评估骨-植入物界面处的相对微动以及股骨中的应力分布。该界面被建模为涉及骨与植入物之间库仑干摩擦的单侧接触。此外，该模型还包括皮质骨和松质骨的不均匀性、各向异性以及塑性。设计了一个与三维网格生成器耦合的自动数据处理器，用于从定量计算机断层扫描（QCT）获得的数据中提取皮质骨几何形状和小梁骨密度的不均匀分布。针对两种典型载荷：模拟单腿站立的载荷和模拟爬楼梯姿势的载荷，进行了初步应用以评估现有骨-假体结构的力学行为。所得结果分为两部分。首先，是骨-柄界面处应力传递和微动的特征。在近端内侧区域，当摩擦系数等于0.6时，剪切微动的峰值达到600微米。对摩擦系数影响的分析表明，剪切和拉伸微动以及剪切和法向应力强烈依赖于该系数。其次，是股骨中的应力表示。诸如静水压力、偏应力和各向异性应力等互补不变量的确定为评估股骨中的应力场带来了更多见解。
