Articular cartilage biomechanics: theoretical models, material properties, and biosynthetic response.

Articular cartilage has unique material properties that enable the cartilage to perform its physiological functions over a lifetime and under a wide range of loading conditions. Numerous studies have investigated the relationship between cartilage properties and composition/structure. For cartilage transplantation and regeneration, it is necessary to know how cartilage maintains its functionality and how cartilage responds to the ever-changing mechanical environment. In this review, we discuss theoretical and experimental studies on the behavior of articular cartilage to load. In the first part, the composition and structure of articular cartilage is presented. In the second part, theoretical models of the mechanical behavior of cartilage, experimental methods for the determination of cartilage properties, and material properties for normal, pathologic, and repair cartilage are summarized. In the third part, the relationship between mechanical loading of the cells and their corresponding biological responses are discussed. The goal for treating joint degeneration in the future lies in cartilage regeneration rather than prosthetic replacement. In order to achieve this goal, it has to be understood how structure and function, metabolic and biochemical properties, and biomechanical performance of articular cartilage can be restored.