Viscotherapy

Hyaluronate ("hye-al-you-ROE-nate") is obtained from rooster combs. Hyaluronic acid is a natural sugar of the glycosaminoglycan family that allows cartilage to hold water. Water accounts for 75 percent of normal cartilage weight and gives cartilage its elasticity and distensiblity.

In osteoarthritis, joints have less hyaluronic acid. In addition, joints may have excess synovial fluid with lower viscosity. Viscosupplementation is the injection of hyaluronan into the joint to give back its normal lubricating and shock-absorbing function and to promote the joint’s ability to produce more hyaluronan.

Currently several preparations are available for use in the United States:

• Hyalgan (sodium hyaluronate): five injections one week apart
• Synvisc (Hylan G-F 20): three injections one week apart
• Orthovisc: three injections, one week apart

Knee pain when injection is given is common. A flare-up of arthritis in the joint one to two days after the injection may occur.

Any time fluid is removed from the joint or injected, a small risk of infection ("septic arthritis") occurs. There are rare reports of "crystal arthritis" called pseudogout, caused by a calcium crystal released in the joint after viscosupplementation injections.

Rare reports of headaches, itching, hives, rashes, facial flushing and shortness of breath have been reported. Their association with the injection of hyaluran into the joint is questionable.

Improvement in joint pain and mobility occurs in about three out of four patients. (About 50 percent of patients injected with a placebo improve too).

Response may last over a year and can be repeated if the initial series leads to some prolonged improvement. Pain relief is comparable to a steroid injection (cortisone shot) but typically sustained over a long period of time. One may experience improvement within days of the first injection or improvement may take up to six weeks after the injections are completed.

Patients who have not responded to NSAIDs or who cannot tolerate them are good candidates, as are patients who have failed to improve with local steroid injections.

Patients with numerous other health problems or those who would not consider a total knee replacement are candidates.

Viscosupplementation is expensive. The total cost for a series of injections is $800 to $1,200 on average.

After an injection we usually ask that you avoid strenuous activity or prolonged (more than one hour) activity for the next 48 hours. Call your doctor if you experience a fever or any acute pain or swelling after an injection.