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. Concomitant use with other intra-articular injectables. Use with caution in severely inflamed knee joints, when lymphatic or venous stasis exists in treatment leg, during lactation, and in those allergic to avian proteins, feathers and egg products. Safety and efficacy may be altered by dilutional effects. Safety and efficacy have not been determined during pregnancy or in children.