Journal of Applied and Computational Mechanics (Jul 2021)

Comparison of Functionally Graded Hip Stem Implants with ‎Various Second-Generation Titanium Alloys

  • Tawakol A. Enab,
  • Noha Fouda,
  • Ibrahim Eldesouky

DOI
https://doi.org/10.22055/jacm.2020.32964.2115
Journal volume & issue
Vol. 7, no. 3
pp. 1315 – 1323

Abstract

Read online

Total hip Arthroplasty (THA) is performed every year at a very high frequency to improve the quality of life of thousands of patients all over the globe. Nevertheless, the expected service life of such surgery remains unsuitable for patients under 50 years old. This is mainly related to stress shielding and the potential adverse tissue reaction to some of the elements of the market-dominant implant materials. In this research, functionally graded (FG) implant designs of several titanium alloys layered with hydroxyapatite (HA) are proposed to provide lower implant stiffness compared to a solid stem to approach the requirements of human bone. Moreover, TNZT (Ti35Nb7Zr5Ta), and TMZF (Ti12Mo6Zr2Fe) second-generation titanium alloys are studied as a replacement for the famous Ti6Al4V alloy to avoid the adverse tissue reactions related to aluminum and vanadium elements. The different FG models are numerically tested using a 3D finite element simulation after virtual implantation in a femur bone under the dynamic load of a patient descending stairs. In the numerical study, the variation in stress distribution and strain energy in a femur bone is assessed for different FG hip stems as well as the axial stiffness of the hip stems. Results indicated an increase in strain energy and von Mises stress in the cortical and cancellous bones using FG hip stems. Additionally, the axial stiffness is reduced for all FG hip stems relative to the commercial Ti6Al4V hip stem.

Keywords