Hyaluronic acid occurs naturally in body tissues and fluids.
It is secreted by cells in synovial membranes and, in healthy synovial joints, maintains viscosity of synovial fluid and supports lubricating and shock-absorbing properties of the cartilage. In osteoarthritis, synovial fluid is decreased in viscosity and elasticity. Sodium hyaluronate and hylan G-F 20 replace diseased synovial fluid. Hyaluronic acid is metabolized by hyaluronidase in synovium. Hypersensivity to hyaluronan.