Intraarticular hyaluronan injections in the treatment of osteoarthritis: state-of-the-art review.

Viscosupplementation (restoring the rheological properties of a tissue matrix) by injection of hyaluronan into the joints has been in use for 2 decades, mostly for osteoarthritis (OA) of the knee, using doses of 20-25 mg of hyaluronan of 500,000 to 2,500,000 M(r), in sequences of 2 to 10 weekly injections. Pain relief appears in a few days, progresses over a few weeks, and often lasts several months. Some data suggest the benefit can last 6 months to one year. Tolerance is universally reported as very good. Those responding to hyaluronan are 65-80%, compared to 30-35% responding to control. Compared to local steroid injections, the effect of hyaluronan appears significantly more lasting. More highly viscoelastic preparations of hyaluronan can be expected to make this therapy even more attractive.