SF is a thin, stringy fluid present in the cavities of synovial joints. It can reduce friction between the articular cartilage and other tissues in joints, to lubricate and cushion them during movement. SF may be classified into normal, noninflammatory, inflammatory, septic, and hemorrhagic, with each group associated with certain diagnoses. Regular SF analysis is commonly performed to determine the cause of acute arthritis. SF contains a large number of proteins originating from synovial tissue, cartilage, and serum. Synovial fluid potentially contains markers for early diagnosis and disease progression in degenerative joint diseases such as osteoarthritis.
