MMP8 and osteonecrosis: Just like types I, II, and III collagens, it could degrade the cartilage proteoglycan, aggrecan, and involved in tissue remodeling.[15,16]MMP-8 was found to be correlated with RA and osteonecrosis of the femoral head.[17,18] Mattey et al found that bath AS disease activity index (BASDAI) was correlated with a group of clustered biomarkers consisting of MMP-8, MMP-9, hepatocyte growth factor, the chemokine, and CXCL8.