Robust optimization of anisotropic porous hip implants for stress-shielding mitigation

Li, Zeyang, Huang, Xuanxuan, Yuan, Hang, Wu, Zhangming ORCID: https://orcid.org/0000-0001-7100-3282 and Ding, Ziyun 2026. Robust optimization of anisotropic porous hip implants for stress-shielding mitigation. International Journal of Mechanical Sciences 325 , 111852. 10.1016/j.ijmecsci.2026.111852

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Abstract

Stress shielding after total hip arthroplasty (THA) is driven by the stiffness mismatch between femoral stems and surrounding bone, which can promote bone resorption and compromise long-term fixation. Porous stems can reduce global stiffness, but many existing designs mainly tune density and provide limited control over directional stiffness, bone-remodeling response, and surgical variability. Here, we present a robust optimization framework for anisotropic porous hip implants based on Varied-shape Voronoi Tessellation (VSVT). The framework assigns programmable relative density, anisotropy ratio, and material orientation, and couples structural compliance with a bone-remodeling objective under uncertainty in the caput-collum-diaphyseal (CCD) angle. In the numerical femur-implant model, the anisotropic robust optimization maintained a comparable expected compliance to the conventional compliance-based baseline, while reducing the expected normalized bone-remodeling mass by 98.9%, from 87.8 to 1.0. Under CCD-angle uncertainty, the same design narrowed the 95% confidence interval of remodeling mass from [75.6, 100.2] to [0.0, 5.8], indicating substantially improved robustness against surgical-angle variation. These results show that programmable anisotropy and robustness control can be integrated into a single porous-implant design workflow, providing a mechanics-based reference for industrial implant design and future clinical translation.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Schools > Engineering
Publisher:	Elsevier BV
ISSN:	0020-7403
Date of First Compliant Deposit:	6 July 2026
Date of Acceptance:	22 June 2026
Last Modified:	06 Jul 2026 13:00
URI:	https://orca.cardiff.ac.uk/id/eprint/187930

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