Hyaluronic acid refers to the gel-like substance that is naturally occurring in the body. It can serve to act as a lubricant or shock absorber for joints. Hyaluronic acid can be extracted from rooster combs or made by bacteria in the laboratory. It has been used as a treatment for the skin and is now being applied to pain management conditions, especially to treat osteoarthritis. Hyaluronic acid is delivered as a series of 3 to 5 injections spaced one week apart and can help reduce the pain from arthritis of the knee.