Department of Mechanical Engineering, Indian Institute of Technology Kharagpur, Kharagpur, India.
Int J Numer Method Biomed Eng. 2023 Jun;39(6):e3709. doi: 10.1002/cnm.3709. Epub 2023 Apr 23.
The functionally graded porous metal-backed (FGPMB) acetabular component has the potential to minimize strain-shielding induced bone resorption, caused by stiffness mismatch of implant and host bone. This study is aimed at a novel design of FGPMB acetabular component, which is based on numerical investigations of the mechanical behavior of acetabular components with regard to common failure scenarios, considering various daily activities and implant-bone interface conditions. Both radial and polar functional gradations were implemented, and the effects of the polar gradation exponent on the failure criteria were evaluated. The relationships between porosity and orthotropic mechanical properties of a tetrahedron-based unit cell were obtained using a numerical homogenization method. Strain-shielding in cancellous bone was relatively lesser for the FGPMB than solid metal-backing. Few nodes around the rim were susceptible to implant-bone interfacial debonding, irrespective of the polar gradation exponent. Although the most favorable bone remodeling predictions were obtained for a polar gradation exponent of 0.1, a sudden change in the porosity was observed near the rim of FGPMB. Bone remodeling patterns were similar for polar gradation exponent of 5.0 and solid metal-backing. Moreover, the volumetric wear was maximum and minimum for polar gradation exponents of 0.1 and 5, respectively. Furthermore, the micromotions of different polar gradation exponents were within a range (20-40 μm) that might facilitate bone ingrowth. Considering common failure mechanisms, the FGPMB having polar gradation exponents in the range of 0.1-0.5 appeared to be a viable alternative to the solid acetabular component, within which a gradation exponent of 0.25 seemed the most appropriate design parameter.
具有梯度多孔金属背衬（FGPMB）的髋臼部件具有降低因植入物与宿主骨之间的刚度不匹配而导致的应变屏蔽引起的骨吸收的潜力。本研究旨在设计一种新型的 FGPMB 髋臼部件，该设计基于对髋臼部件在常见失效情况下的力学行为的数值研究，考虑了各种日常活动和植入物-骨界面条件。实施了径向和极向功能梯度，并评估了极向梯度指数对失效准则的影响。使用数值均匀化方法获得了基于四面体单元的孔隙率与各向异性力学性能之间的关系。与实体金属背衬相比，FGPMB 中的松质骨应变屏蔽程度较低。无论极向梯度指数如何，边缘周围的少数节点都容易发生植入物-骨界面脱粘。尽管对于极向梯度指数为 0.1 时获得了最有利的骨重塑预测，但在 FGPMB 的边缘附近观察到了孔隙率的突然变化。对于极向梯度指数为 5.0 和实体金属背衬，骨重塑模式相似。此外，对于极向梯度指数为 0.1 和 5，体积磨损分别最大和最小。此外，不同极向梯度指数的微动在（20-40μm）范围内，这可能有利于骨长入。考虑到常见的失效机制，具有 0.1-0.5 范围内极向梯度指数的 FGPMB 似乎是实体髋臼部件的可行替代品，其中梯度指数为 0.25 似乎是最合适的设计参数。
