Cartilage is a dense connective tissue that functions to withstand and distribute load (1 ). Articular cartilage lines the ends of long bones and distributes loads across the joints. It consists of a dense collagenous matrix (primarily collagen type II, with smaller amounts of other collagens, including types I, V, VI, IX, and XI), embedded in a high concentration of aggregating proteoglycan, aggrecan. The collagen provides tensile properties, and the proteoglycans confer compressive properties and resiliency. There is a sparse population of a single cell type, the chondrocyte, distributed throughout the tissue. These cells synthesize and maintain the cartilaginous matrix in a regulated fashion that involves breakdown of matrix components, release of proteolytic products from the tissue, and synthesis and incorporation of new components into the matrix.
