After joint injury and in early stages of osteoarthritis, increased amounts ofcartilage oligomeric matrix protein (COMP) fragments are released intosynovial fluid.8 COMP, which belongs to the family of thrombospondins, is currentlybeing used as a biomarker of joint destruction,9 as its concentration correlates with both the severity of the diseaseas well as with the number of affected joints. This evidence concerns the gene COMP and osteoarthritis.