Moussa Ahmed, Rahman Shakurur, Xu Manman, Tanzer Michael, Pasini Damiano
Department of Mechanical Engineering, McGill University, Montreal, Quebec, H3A0C3, Canada.
Division of Orthopaedics, Department of Surgery, McGill University, Jo Miller Orthopaedic Research Laboratory, Montreal, Quebec, H3G1A4, Canada.
J Mech Behav Biomed Mater. 2020 May;105:103705. doi: 10.1016/j.jmbbm.2020.103705. Epub 2020 Feb 24.
Aseptic loosening and mechanical failure of acetabular reinforcement components are among the main causes of their reduced service life. Current acetabular implants typically feature a structural solid layer that provides load bearing capacity, coated with a foam of uniform porosity to reduce stress shielding and implant loosening. This paper presents an alternative concept for a 3D printed cage that consists of a multifunctional fully porous layer with graded attributes that integrate both structural function and bone in-growth properties. The design comprises a hemispherical cup affixed to a superior flange with architecture featuring an optimally graded porosity. The methodology here presented combines an upscaling mechanics scheme of lattice materials with density-based topology optimization, and includes additive manufacturing constraints and bone ingrowth requirements in the problem formulation. The numerical results indicate a 21.4% reduction in the maximum contact stress on the bone surface, and a 26% decrease in the bone-implant interface peak micromotion, values that are indicative of enhanced bone ingrowth and implant long-term stability.
髋臼强化部件的无菌性松动和机械故障是其使用寿命缩短的主要原因。当前的髋臼植入物通常具有一个提供承载能力的结构实体层，表面涂覆有孔隙率均匀的泡沫，以减少应力遮挡和植入物松动。本文提出了一种用于3D打印髋臼杯的替代概念，该髋臼杯由具有渐变属性的多功能全多孔层组成，兼具结构功能和骨长入特性。该设计包括一个固定在上部凸缘上的半球形杯，其结构具有最佳渐变孔隙率。本文提出的方法将晶格材料的放大力学方案与基于密度的拓扑优化相结合，并在问题公式中纳入了增材制造约束和骨长入要求。数值结果表明，骨表面的最大接触应力降低了21.4%，骨-植入物界面的峰值微动降低了26%，这些数值表明骨长入和植入物长期稳定性得到了增强。
