Type II collagen is composed of a triple helix of three identical α chains. These molecules associate to form a fibril that is stabilized by intermolecular crosslinks1. Damage to the fibrillar meshwork, made up of primarily type II collagen (z 90–95%), maybe a critical event in the pathology of many arthritides, due in part to the very slow rate of collagen turnover within the cartilage2.

Type II collagen and aggrecan (a large, aggregating proteoglycan) are the two major components of the extracellular matrix of cartilage. The collagen, which is present in a fibrillar form, provides tensile strength whereas the aggrecan is responsible for compressive stiffness of cartilage3-5. Early damage to type II collagen is predominantly pericellular/ territorial suggests that in the majority of cases collagen damage was mediated by the chondrocyte.