Design of orthopedic implants made of porous metallic materials using additive manufacturing technologies

使用增材制造技术设计由多孔金属材料制成的骨科植入物

• 批准号: RGPIN-2017-05958
• 负责人: Nuño, Natalia
• 金额: $ 1.82万
• 依托单位: École de technologie supérieure
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=680441
• 关键词: Design; orthopedic; implants; made; porous

Long-term survivorship of orthopedic implants remains a challenge as patients are becoming younger and more active. One factor compromising the longevity of the implant is bone resorption believed to be due to stress shielding. Bone is a living tissue and reacts to its mechanical stimuli. When bone is removed to be replaced by an artificial implant, a redistribution of the stresses within the bone occurs. This stress shielding phenomenon occurs because of the large difference in rigidity between the metallic implant and the surrounding bone. The bone is thus stress shielded, consequently the bone is resorbed and its density decreased, eventually leading to failure of the arthroplasty. New materials are needed to mimic the natural bone to reduce the stress shielding phenomenon.****Nowadays, additive manufacturing technologies make possible complex, well-controlled porous materials such as metals with high porosity (50-80%) having material properties tailored to the desired need. Such new materials can be used to design implants with reduced stiffness to diminish the stress shielding. Furthermore, they allow for good osteointegration within the porosity (cell growth through the implant for appropriate stability). Infinity of structures at the mesoscale can be fabricated, thus infinity of mechanical properties can be designed. The implant can be functionally graded by having regions of high porosity and other regions with less porosity or no porosity. Finally, customized implants adapted to each patient can be manufactured.****The aim of this research program is to design and model new porous metallic materials obtained using additive manufacturing technologies for orthopedic applications. Numerical modeling is widely used to predict the mechanical behavior of implants of total joint replacements. Accurate prediction can be obtained because of the homogeneity of the solid material. However, for highly porous metallic materials, the mechanical behavior is not predicted accurately since the structure at the mesoscale is made of slender struts and voids. The nominal dimensions at the mesoscale are of the order of hundreds of microns. As an example for an implant, strut diameters are approximately 500 microns and pores 800 microns. The discrepancy between nominal and actual (manufactured) dimensions becomes important for highly porous materials. As a result, the mechanical behavior predicted with finite element models differ importantly from experimental data. Finite element analysis is essential to study the overall (at the macroscale) and local (at the mesoscale) mechanical behavior of porous materials to design implants, before mechanical testing and pre-clinical testing. This research program will develop numerical tools to predict the porous metallic materials using experiments to validate the numerical model.******

骨科植入物的长期生存率仍然是一个挑战，因为患者越来越年轻，越来越活跃。影响种植体寿命的一个因素是骨吸收，据信是由于应力遮挡。骨是一种活组织，对机械刺激有反应。当骨被移除以被人工植入物替代时，骨内的应力发生重新分布。这种应力遮挡现象的发生是因为金属植入物和周围骨之间的刚度差异很大。因此，骨被应力屏蔽，因此骨被再吸收并且其密度降低，最终导致关节成形术失败。需要新的材料来模拟天然骨，以减少应力屏蔽现象。如今，增材制造技术使复杂的、控制良好的多孔材料成为可能，例如具有高孔隙率（50-80%）的金属，其具有根据所需需求定制的材料特性。这种新材料可用于设计刚度降低的植入物，以减少应力屏蔽。此外，它们允许孔隙内的良好骨整合（通过植入物的细胞生长以获得适当的稳定性）。可以在介观尺度上制造无限多的结构，从而可以设计无限多的力学性能。植入物可以通过具有高孔隙率的区域和具有较少孔隙率或没有孔隙率的其他区域而在功能上分级。最后，可以制造适合每个患者的定制植入物。*该研究计划的目的是设计和建模使用增材制造技术获得的新型多孔金属材料，用于骨科应用。数值模拟被广泛用于预测全关节置换术中植入物的力学行为。由于固体材料的均匀性，可以获得准确的预测。然而，对于高度多孔的金属材料，由于细观尺度的结构是由细长的支柱和空隙组成的，因此不能准确地预测其力学行为。中尺度的标称尺寸为数百微米的量级。作为植入物的一个例子，支柱直径约为500微米，孔约为800微米。对于高度多孔的材料，标称尺寸和实际（制造）尺寸之间的差异变得很重要。因此，有限元模型预测的力学行为与实验数据有很大的不同。在机械测试和临床前测试之前，有限元分析对于研究多孔材料的整体（宏观尺度）和局部（中尺度）力学行为以设计植入物至关重要。该研究计划将开发数值工具，使用实验来验证数值模型，以预测多孔金属材料。*