Department of Mechanical Engineering, Columbia University, New York, NY, United States.
Department of Biomedical Engineering, Columbia University, New York, NY, United States.
Osteoarthritis Cartilage. 2023 Dec;31(12):1594-1601. doi: 10.1016/j.joca.2023.08.008. Epub 2023 Aug 24.
Wear of articular cartilage is not well understood. We hypothesize that cartilage wears due to fatigue failure in repetitive compression instead of reciprocating friction.
This study compares reciprocating sliding of immature bovine articular cartilage against glass in two testing configurations: (1) a stationary contact area configuration (SCA), which results in static compression, interstitial fluid depressurization, and increasing friction coefficient during reciprocating sliding, and (2) a migrating contact area configuration (MCA), which maintains pressurization and low friction while producing repetitive compressive loading in addition to reciprocating sliding. Contact pressure, sliding duration, and sliding distance were controlled to be similar between test groups.
SCA tests exhibited an average friction coefficient of μ=0.084±0.032, while MCA tests exhibited a lower average friction coefficient of μ=0.020±0.008 (p<10). Despite the lower friction, MCA cartilage samples exhibited clear surface damage with a significantly greater average surface deviation from a fitted plane after wear testing (R=0.125±0.095 mm) than cartilage samples slid in a SCA configuration (R=0.044±0.017 mm, p=0.002), which showed minimal signs of wear. Polarized light microscopy confirmed that delamination damage occurred between the superficial and middle zones of the articular cartilage in MCA samples.
The greatest wear was observed in the group with lowest friction coefficient, subjected to cyclical instead of static compression, implying that friction is not the primary driver of cartilage wear. Delamination between superficial and middle zones implies the main mode of wear is fatigue failure under cyclical compression, not fatigue or abrasion due to reciprocating frictional sliding.
关节软骨的磨损尚不清楚。我们假设软骨的磨损是由于在重复压缩而不是往复摩擦中产生的疲劳失效。
本研究比较了在两种测试配置下不成熟牛关节软骨对玻璃的往复滑动：（1）固定接触面积配置（SCA），导致静态压缩、间质液减压和往复滑动过程中摩擦系数增加，（2）迁移接触面积配置（MCA），在产生往复滑动的同时保持加压和低摩擦，并产生重复压缩载荷。控制接触压力、滑动持续时间和滑动距离在实验组之间相似。
SCA 测试的平均摩擦系数为 μ=0.084±0.032，而 MCA 测试的平均摩擦系数为 μ=0.020±0.008（p<10）。尽管摩擦系数较低，但 MCA 软骨样本显示出明显的表面损伤，磨损试验后与拟合平面的平均表面偏差明显更大（R=0.125±0.095mm），比在 SCA 配置中滑动的软骨样本（R=0.044±0.017mm，p=0.002），后者磨损迹象最小。偏光显微镜证实，在 MCA 样本的表层和中层之间发生了分层损伤。
在摩擦系数最低、承受循环而不是静态压缩的组中观察到最大磨损，这表明摩擦不是软骨磨损的主要驱动因素。表层和中层之间的分层表明主要磨损模式是周期性压缩下的疲劳失效，而不是由于往复摩擦滑动引起的疲劳或磨损。
