In vivo sliding distance on the metal‐on‐polyethylene total hip arthroplasty articulation using patient‐specific gait analysis

Metal‐on‐polyethylene (MoP) is the most commonly used bearing surface in primary total hip arthroplasty (THA). Polyethylene wear debris remains a major concern. Studies investigating the wear performance based on patient‐specific in vivo kinematics and component orientation remains largely lacking. The primary goal of this study was to identify patterns of the distribution of sliding distance and cross‐shear ratio among THA patients. A validated approach combining dual fluoroscopic imaging system and computed‐tomography was utilized to quantify in vivo gait kinematics and component orientations in 48 total hips. The distribution of accumulated sliding distance and cross‐shear ratio over the polyethylene bearing surface was calculated and analyzed using principal component analysis (PCA). Strong patient‐specific variation in sliding distance and cross‐shear ratio was observed. PCA detected two principal components (PCs) of the sliding distance that together contribute to 94.8% of the total variation. PCA detected four PCs that together contribute to 86% of the total variation of the cross‐shear ratio. Regression analysis identified a positive association between cross‐shear magnitude and axial and frontal range of motion (RoM). Increased cup inclination, stem anteversion, and reduced cup anteversion may lead to superiorly distributed high cross‐shear region, potentially accelerating wear. Our study investigated, in vivo sliding distance and cross‐shear pattern using a comprehensive patient‐specific dataset and detected several wear indicators under in vivo conditions. These findings provided useful reference values that may help to assess wear in MoP THA patients.