Design optimization of functionally graded lattice infill total hip arthroplasty stem for stress shielding reduction

Jumpei Nomura, Akihiro Takezawa*, Heng Zhang, Mitsuru Kitamura

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Reducing stress shielding of stem-inserted femurs in total hip arthroplasty caused by the high stiffness of the stem is an emerging medical engineering issue. In this study, a numerical design optimization methodology lattice infill stem was developed to realize a stem, balancing the low stiffness and strength requirements. Two pairs of models and loading conditions were introduced for the stress shielding and strength criteria. The objective function was set as the weighted sum of the criteria. Its effective density distribution was optimized by handling the representative size of the lattice as a design variable, assuming that the so-called body-centered cubic lattice was the base shape of the lattice. In the optimization, the approximated model of the lattice was handled as a solid material with the effective physical properties of the lattice derived by the homogenization method. After optimization, the detailed lattice stem geometry was modeled based on the obtained optimal lattice distribution, and the actual performance was numerically evaluated. The developed stem increased the stress applied to the remaining femur by 32.4% compared with the conventional stem.

Original languageEnglish
Pages (from-to)515-525
Number of pages11
JournalProceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine
Volume236
Issue number4
DOIs
Publication statusPublished - 2022 Apr

Keywords

  • Stress shielding
  • additive manufacturing
  • lattice structure
  • stem design optimization
  • total hip arthroplasty

ASJC Scopus subject areas

  • Mechanical Engineering

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