TY - JOUR
T1 - Design optimization of functionally graded lattice infill total hip arthroplasty stem for stress shielding reduction
AU - Nomura, Jumpei
AU - Takezawa, Akihiro
AU - Zhang, Heng
AU - Kitamura, Mitsuru
N1 - Funding Information:
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was partially supported by the JST, A-Step, Seeds development type (JPMJTR192A).
Publisher Copyright:
© IMechE 2022.
PY - 2022/4
Y1 - 2022/4
N2 - 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.
AB - 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.
KW - Stress shielding
KW - additive manufacturing
KW - lattice structure
KW - stem design optimization
KW - total hip arthroplasty
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U2 - 10.1177/09544119221075140
DO - 10.1177/09544119221075140
M3 - Article
AN - SCOPUS:85124341962
SN - 0954-4119
VL - 236
SP - 515
EP - 525
JO - Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine
JF - Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine
IS - 4
ER -