Wear behavior and material performance optimization of articular cartilage under cross-shear motion

BackgroundWith population aging and an increase in sports injuries, articular cartilage wear has become increasingly severe, significantly impairing patients' quality of life. Cross-shear motion is a common loading pattern in daily joint activities, yet its effects on cartilage and counterpart materials remain insufficiently investigated.ObjectiveTo investigate the wear behavior and underlying mechanisms of articular cartilage under cross-shear motion, and to compare the wear resistance of different artificial joint materials, so as to propose material optimization strategies suitable for this motion pattern.MethodsFresh bovine knee femoral cartilage was used to simulate the human cartilage environment under various cross-shear conditions and loading regimes. Stepwise loading, microhardness testing, cartilage compression deformation measurements, and surface wettability tests were performed to systematically analyze the tribological characteristics and wear mechanisms of each material. The evaluated materials included CoCrMo, ultra-high molecular weight polyethylene, and polyether-ether-ketone (PEEK).ResultsCross-shear motion significantly increased wear in all materials. CoCrMo exhibited the largest increase (ΔK = 230.51 ± 25.67%), while PEEK showed the smallest increase in wear rate (138.37%). No significant linear correlation was found between material hardness and cross-shear wear rate (r = -0.32, p > 0.05). In terms of dynamic wettability, PEEK performed best, with a hysteresis angle 38.46% lower than that of natural cartilage, and its energy dissipation parameters were close to those of natural cartilage, indicating the best cartilage compatibility.ConclusionUnder cross-shear conditions, PEEK demonstrates the best overall wear resistance and biomechanical compatibility, suggesting its potential as a promising material for joint repair. The wear mechanisms revealed in this study provide experimental evidence and reference for performance optimization and clinical selection of artificial joint materials.