Finite Element Analysis of Porous Titanium Alloy Hip Stem to Evaluate the Biomechanical Performance During Walking and Stair Climbing

Abstract

Despite the success of cementless hip stem, stress shielding still presents a serious problem leading to bone resorption. Stems incorporating porous cellular structures represent a promising solution. Therefore, this study validates the finite element models of titanium (Ti) alloy (Ti-6Al-4V) porous stem and effective porous stems. Several effective porous stems with strut thicknesses 0.33 mm -1.25 mm (18% - 90% porosity) under different loading conditions were analyzed. The results of finite element models revealed that changing the load type and porosity affect stress shielding. Climbing loads yield the maximum stress levels while walking loads result in the lowest stresses in the stems. Furthermore, the point load results in the maximum stress shielding and micromotions (−19% to 18%, 40 µm to 703 µm), as compared to walking (−17.5% to 3%, 35 µm to 242 µm) and climbing loads (−7% to 1.6%, 30 µm to 221 µm). Finally, effective porous stems of strut thickness 0.87 mm exhibit the lowest stress shielding signals (<5%) under all loading conditions.