Arabnejad Khanoki Sajad, Pasini Damiano
Mechanical Engineering Department, McGill University, Montreal, Quebec, Canada.
J Biomech Eng. 2012 Mar;134(3):031004. doi: 10.1115/1.4006115.
Revision surgeries of total hip arthroplasty are often caused by a deficient structural compatibility of the implant. Two main culprits, among others, are bone-implant interface instability and bone resorption. To address these issues, in this paper we propose a novel type of implant, which, in contrast to current hip replacement implants made of either a fully solid or a foam material, consists of a lattice microstructure with nonhomogeneous distribution of material properties. A methodology based on multiscale mechanics and design optimization is introduced to synthesize a graded cellular implant that can minimize concurrently bone resorption and implant interface failure. The procedure is applied to the design of a 2D left implanted femur with optimized gradients of relative density. To assess the manufacturability of the graded cellular microstructure, a proof-of-concept is fabricated by using rapid prototyping. The results from the analysis are used to compare the optimized cellular implant with a fully dense titanium implant and a homogeneous foam implant with a relative density of 50%. The bone resorption and the maximum value of interface stress of the cellular implant are found to be over 70% and 50% less than the titanium implant while being 53% and 65% less than the foam implant.
全髋关节置换术的翻修手术通常是由植入物结构兼容性不足引起的。其中两个主要原因是骨-植入物界面不稳定和骨吸收。为了解决这些问题，在本文中我们提出了一种新型植入物，与目前由全固态或泡沫材料制成的髋关节置换植入物不同，它由具有非均匀材料特性分布的晶格微结构组成。引入了一种基于多尺度力学和设计优化的方法来合成一种渐变多孔植入物，该植入物可以同时最小化骨吸收和植入物界面失效。该方法应用于具有优化相对密度梯度的二维左植入股骨的设计。为了评估渐变多孔微结构的可制造性，通过快速成型制作了一个概念验证模型。分析结果用于将优化后的多孔植入物与全致密钛植入物以及相对密度为50%的均匀泡沫植入物进行比较。发现多孔植入物的骨吸收和界面应力最大值比钛植入物分别减少了70%以上和50%，比泡沫植入物分别减少了53%和65%。
