A Customized Distribution of the Coefficient of Friction of the Porous Coating in the Short Femoral Stem Reduces Stress Shielding

Stress shielding and aseptic loosening have been identified as adverse effects of short-stem total hip arthroplasty resulting in hardware failure. However, there is a gap in research regarding the impact of stress shielding in customized porous coatings. The purpose of this study was to optimize the distribution of the coefficients of friction in the porous coating of a metaphyseal femoral stem to minimize stress shielding. Static structural analysis of an implanted short, tapered-wedge stem with a titanium porous coating was performed with the use of Analysis System Mechanical Software under axial loading. To limit computational time, we randomly sampled only 500 of the possible combinations of coefficients of friction. Results indicate that the coefficient of friction in the distal lateral porous coating significantly affected the mid-distal medial femoral surface and lateral femoral surface. The resultant increased proximal strains resulted from an increased coefficient of friction in lateral porous coating and a reduction in the coefficient of friction in medial mid-distal coating. These findings suggest that a customized porous coating distribution may produce strain patterns that are biomechanically closer to intact bone, thereby reducing stress shielding in short femoral stems.