Aggrecan is a proteoglycan, and it possesses a core protein with covalently attached sulfated glycosaminoglycan (GAG) chains. Within the extracellular matrix aggrecan occurs only in the form of proteoglycan aggregates. The GAG chains provide aggrecan with its high anionic charge whereas aggregation endows it with a large size. Both the charge and size properties are essential for normal aggrecan function and hence articular cartilage function[1]. As a structural proteoglycan, aggrecan appears to be important in mediating chondrocyte-chondrocyte and chondrocyte-matrix interactions[2]. Aggrecan can be metabolized by several members of the ADAMTS family possess some degree of aggrecanolytic activity in vitro, including ADAMTS-5. It cleaves human aggrecan to produce the fragments found in synovial fluid and cartilage[3].