TIMP1 and osteoarthritis: In conclusion, the results of our studies suggest that medial plica and pannus-like tissue may play roles in the process of cartilage degradation in OA knee by producing ECM-degrading enzymes during inflammation and that the imbalance between TIMP and MMP levels in these tissues increases protease activity in the medial compartment and this may also contribute to cartilage breakdown and progression of osteoarthritis.