Non-avian-derived hyaluronan for the treatment of osteoarthritis of the knee

Osteoarthritis is among the leading causes of pain and reduced function in the USA, and its prevalence is increasing as the 'baby boom' generation ages. Present-day therapy is directed at the relief of pain, but the treatment armamentarium for moderate-to-severe osteoarthritis has been incomplete. Most existing treatments do not provide long-lasting effective pain relief and most also carry the risk of potentially distressing and/or dangerous systemic adverse effects. Intra-articular hyaluronan injections have significantly reduced pain for a majority of patients with osteoarthritis of the knee. Although the exact mechanism of action is not known, this treatment replaces lost endogenous hyaluronan and has direct actions on nerve endings, synovial cells and chondrocytes. This article discusses the rationale behind the development of intra-articular hyaluronan injections and describes one formulation that was the first highly purified result of a well-established extraction technique and a non-animal-derived exogenous origin.