Mechanical behaviour investigation of PEEK coated titanium alloys for hip arthroplasty using finite element analysis

Abstract

The poor mechanical strength of CP-Ti and the toxic properties of Ti6Al4V due to aluminum and vanadium contents stand out as essential issues to consider while using for total hip arthroplasty (THA). In this concern, the current study focused on investigating the stress-deformation and fatigue behaviour of three different titanium alloy stems (Ti6Al4V, Ti6Al7Nb, and Ti6Al4V ELI) with alumina ceramic femoral head and PEEK coatings using finite element analysis. The stress-deformation and fatigue behaviours were examined with and without PEEK coatings for estimating their feasibility in reducing stress-shielding effects considering knee bend gait activity for average 75 wt standard loading conditions. The fatigue behaviours were investigated using Goodman's mean stress fatigue theory by numerically analyzing employed materials' S-N (alternating stress-life cycles) curves. It was observed from the investigation that the Ti6Al7Nb stem with alumina ceramic femoral head employing PEEK coatings performed superior to other studied material combinations as it showed the lowest equivalent von-mises stresses (265.12 MPa) and the highest factor of safety (2.2895). The investigation showed that all the studied material combinations could survive for at least 10 million cycles according to their S-N curves data and respective yield strengths. Further, the employment of PEEK coatings showed their feasibility in reducing stress-shielding effects compared to bare hip implant models with a considerable increase in factor of safety.