Saravana Kumar Gurunathan, George Subin Philip
1 Department of Engineering Design, Indian Institute of Technology Madras, Chennai, India.
2 Department of Mechanical Engineering, Amal Jyothi College of Engineering, Kottayam, India.
Proc Inst Mech Eng H. 2017 Feb;231(2):149-159. doi: 10.1177/0954411916686125. Epub 2017 Jan 5.
This work proposes a methodology involving stiffness optimization for subject-specific cementless hip implant design based on finite element analysis for reducing stress-shielding effect. To assess the change in the stress-strain state of the femur and the resulting stress-shielding effect due to insertion of the implant, a finite element analysis of the resected femur with implant assembly is carried out for a clinically relevant loading condition. Selecting the von Mises stress as the criterion for discriminating regions for elastic modulus difference, a stiffness minimization method was employed by varying the elastic modulus distribution in custom implant stem. The stiffness minimization problem is formulated as material distribution problem without explicitly penalizing partial volume elements. This formulation enables designs that could be fabricated using additive manufacturing to make porous implant with varying levels of porosity. Stress-shielding effect, measured as difference between the von Mises stress in the intact and implanted femur, decreased as the elastic modulus distribution is optimized.
这项工作提出了一种方法，该方法涉及基于有限元分析的特定个体非骨水泥型髋关节植入物设计的刚度优化，以减少应力屏蔽效应。为了评估由于植入物插入导致的股骨应力应变状态的变化以及由此产生的应力屏蔽效应，针对临床相关加载条件对带有植入物组件的切除股骨进行了有限元分析。选择冯·米塞斯应力作为区分弹性模量差异区域的标准，通过改变定制植入物柄部的弹性模量分布，采用了刚度最小化方法。刚度最小化问题被表述为材料分布问题，而不明确惩罚部分体积单元。这种表述使得能够设计出可使用增材制造制造的具有不同孔隙率水平的多孔植入物。以完整股骨和植入股骨中冯·米塞斯应力的差值来衡量的应力屏蔽效应，随着弹性模量分布的优化而降低。
