Intra-articular hyaluronans in knee osteoarthritis: rationale and practical considerations.

Intra-articular hyaluronans are used to treat pain associated with osteoarthritis of the knee. Many controlled clinical studies have demonstrated their efficacy for this indication. The rationale for the use of hyaluronans therapeutically is based on observations that hyaluronic acid is an important component of the synovial fluid acting as a cushion and lubricant for the joint and also serving as a major component of the extracellular matrix of the cartilage, helping to enhance the ability of cartilage to resist shear and maintain a resiliency to compression. While intra-articular hyaluronans are indicated at this time only for the treatment of pain in osteoarthritis of the knee, there are data to suggest that they may also be useful in treating degenerative disease of other articular joints, as well as have an impact on disease progression. The mechanisms by which hyaluronans mediate their clinical benefit seem to be multifactorial and biologically related, in contrast to the notion that they provide only viscous fluid replacement. The safety profile of intra-articular hyaluronans is very favorable and, because they are used as a local therapy, there are no known drug interactions-an advantage for patients receiving treatment for comorbid conditions. Some adverse effects, such as pseudosepsis, have been associated with cross-linked hyaluronan agents and do not appear to be class related.