Healthy knees contain a substance called hyaluronan that lubricates the joint and acts as a shock absorber between the bones of the knee. As you get older, the chemicals in hyaluronic acid begin breaking down, and levels of hyaluronic acid decrease. Lower levels of the natural lubricant limit joint motion and eventually cause pain and stiffness in the joint. Osteoarthritis is a degenerative disease and will continue to progress without intervention.
Viscosupplementation with hyaluronic acid involves the injection of a thick, gel-like substance directly into the knee joint. The gel relieves pain by lubricating and cushioning the knee joint. Hyaluronic acid (HA) is widely distributed throughout the body and is a significant component of synovial fluid found in joints. Viscosupplementation with HA is most commonly used to treat osteoarthritis of the knee. It enables bones to move smoothly over one another, reducing friction and inflammation caused from bones rubbing against each other. Most patients experience pain relief and improved mobility soon after the injection. There is no evidence, however, showing that viscosupplementation reverses the arthritic process or re-grows cartilage.
Viscosupplementation does not interfere with other medications you may be taking for osteoarthritis and can provide pain relief for up to 6 months. It is typically used in patients who do not respond well to treatment with exercise, weight loss, pain relievers, or physical therapy. When compared with cortisone injections, viscosupplementation does not work as quickly. However, the overall beneficial results are longer-lasting due to the enhancement of the body's natural process of healing.
Traditional treatment for knee osteoarthritis has primarily been to mask the pain with drugs (eg, NSAIDS or cortisone), weight loss, exercise, and physical therapy. Patients who achieve insufficient pain relief and mobility from these treatments are candidates for viscosupplementation. The goals of viscosupplementaton are to temporarily promote better knee mobility, reduce pain, and possibly slow osteoarthritis progression. Three to five injections given a week apart can provide up to 6 months of pain relief.
Viscosupplementation of the Knee: Procedure Snapshot
The doctor will first disinfect the area and administer a local anesthetic. The patient is usually lying on their back with the knee straight or slightly bent (20 to 30 degrees). The doctor will then inject a small amount of hyaluronic acid into the space in the joint on one side of the kneecap.
This same-day procedure takes several minutes to complete. There may be mild discomfort afterward and typical injection site reactions include local redness, swelling and bruising of joint. Usually rehabilitation exercises to improve muscle strength and mobility are prescribed after treatment.
Adverse effects associated with viscosupplementation are infrequent and usually mild—most commonly, injection site pain, swelling, stiffness, skin warmth and redness, and infection. In rare instances an injection may cause inflammation of a nearby bursa.