Composition and structure of articular cartilage - A template for tissue repair

The authors review the structure and composition of articular cartilage. Th is tissue is composed of an extensive extracellular matrix synthesized by c hondrocytes. It contains different zones with respect to depth from the art icular surface and has a regional organization around the chondrocytes. Its composition varies regionally and zonally in its collagen and proteoglycan contents and those of other matrix molecules. There is a macrofibrillar co llagen network and a microfilamentous network about which other noncollagen ous molecules are organized. Its structure and composition are reflective o f its special mechanical properties that primarily reflect its tensile stre ngth (collagens) and compressive stiffness (proteoglycan aggrecan) and cell -matrix interactions (noncollagenous proteins).