Viscosupplementation is a procedure that involves injecting a thick, gel-like substance (hyaluronate) into the joint. The procedure is approved for the treatment of osteoarthritis of the knee. It's also being studied as a treatment for the hip, shoulder, and ankle. Hyaluronate injections are considered treatments, not drugs. With osteoarthritis, the cartilage of a joint breaks down or wears away. There is also loss of joint lubrication, which normally makes a joint glide with ease, as synovial fluid loses its viscosity (i.e., thickness, stickiness, consistency). The loss of lubrication contributes to joint pain, stiffness, and limited mobility. Normal synovial fluid contains hyaluronic acid. Viscosupplementation was developed as a way to improve the lubrication of synovial fluid, reduce pain associated with osteoarthritis, and improve a patient's level of activity and function.

Availability of Viscosupplementation Products

In the United States, the FDA approved viscosupplementation in 1997 for osteoarthritis of the knee. The procedure had already been used in Asia and Europe for several years. Currently, there are five hyaluronic-acid based products (hyaluronates) used for viscosupplementation, which are listed below in the order the FDA approved them:

• Hyalgan (5/28/1997)

• Synvisc (8/8/1997)

• Supartz (1/24/2001)

• Orthovisc (2/5/2004)

• Euflexxa (12/3/2004)

When Is Viscosupplementation an Appropriate Treatment?

Generally speaking, as with any treatment, the result of viscosupplementation is likely better before severe damage has been done. The procedure is usually used after patients have tried and failed other treatment options.

The injections, which go directly into your knee joint, can be given in one or both knees at the same time. If there is fluid around your knee joint, your doctor can remove it at the same time as the injection using the same needle stick. Synvisc, Orthovisc, and Euflexxa are injected weekly for three weeks. Hyalgan and Supartz are injected weekly for five weeks.

Has Viscosupplementation Been Proven Effective?

Studies have tried to ascertain the effectiveness of viscosupplementation for mild or moderate osteoarthritis, compared to corticosteroid injection or NSAIDs. The results are inconclusive. At best, it was concluded that of the patients who did obtain pain relief from the procedure, most found the relief to occur eight to twelve weeks after initial treatment. Some resources pitched viscosupplementation as a way to delay joint replacement surgery. However, there has been no conclusive evidence that viscosupplementation delays or halts the disease course of osteoarthritis. The procedure is not a cure for osteoarthritis and is not approved for rheumatoid arthritis.

Important Things to Know about Viscosupplementation

There are important facts you should know about viscosupple-mentation. The benefit of viscosupplementation is a long-term effect — it starts weeks or months after injection and lasts for several months — so don't expect to notice immediate pain relief following treatment. You may have a local reaction at the injection site; applying ice should help with any minor pain or swelling.

It is recommended that you not engage in strenuous activity or unnecessary or excessive weight bearing on the leg for forty-eight hours after the injection. If you have an allergy to eggs or poultry, be sure to tell your doctor. Some, but not all, of the products used for viscosupplementation are made from rooster combs.