Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, 76100, Israel.
Adv Mater. 2021 May;33(18):e2005513. doi: 10.1002/adma.202005513. Epub 2021 Mar 24.
Healthy articular cartilage, covering the ends of bones in major joints such as hips and knees, presents the most efficiently-lubricated surface known in nature, with friction coefficients as low as 0.001 up to physiologically high pressures. Such low friction is indeed essential for its well-being. It minimizes wear-and-tear and hence the cartilage degradation associated with osteoarthritis, the most common joint disease, and, by reducing shear stress on the mechanotransductive, cartilage-embedded chondrocytes (the only cell type in the cartilage), it regulates their function to maintain homeostasis. Understanding the origins of such low friction of the articular cartilage, therefore, is of major importance in order to alleviate disease symptoms, and slow or even reverse its breakdown. This progress report considers the relation between frictional behavior and the cellular mechanical environment in the cartilage, then reviews the mechanism of lubrication in the joints, in particular focusing on boundary lubrication. Following recent advances based on hydration lubrication, a proposed synergy between different molecular components of the synovial joints, acting together in enabling the low friction, has been proposed. Additionally, recent development of natural and bio-inspired lubricants is reviewed.
健康的关节软骨覆盖在髋关节和膝关节等主要关节的骨端，呈现出自然界中最有效的润滑表面，其摩擦系数低至 0.001，可承受生理上的高压力。如此低的摩擦力对于其健康确实至关重要。它最大限度地减少了磨损，从而减少了与骨关节炎（最常见的关节疾病）相关的软骨退化，并且通过减少对机械转导、嵌入软骨的软骨细胞（软骨中唯一的细胞类型）的剪切应力，它调节其功能以维持体内平衡。因此，了解关节软骨如此低摩擦的起源对于缓解疾病症状、减缓甚至逆转其退化非常重要。本进展报告考虑了摩擦行为与软骨细胞力学环境之间的关系，然后回顾了关节中的润滑机制，特别是关注边界润滑。基于水合润滑的最新进展，提出了滑液关节中不同分子成分之间协同作用的假说，共同实现低摩擦。此外，还回顾了天然和仿生润滑剂的最新发展。
