Viscosupplementation with hyaluronic acid (hyaluronan or hyaluronate) entails injection of a thick, gel-like substance that relieves pain by lubricating and cushioning your knee joint. Hyaluronic acid (HA) is widely distributed throughout the body—such as in skin, cartilage, vitreous humor of the eye—and is a significant component of synovial fluid found in joints. Hyaluronan also coats each articular cartilage cell (chondrocyte) and has anti-inflammatory effects
Viscosupplementation with HA is most commonly used to treat osteoarthritis of the knee. It enables bones to move smoothly over one another and acts as a shock absorber to for joint loads. Many patients have reported pain relief and improved mobility with this treatment, but not all patients have a sufficient response to therapy. There is no evidence that shows it 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.
Viscosupplementation has been proven safe in clinical trials. When compared with cortisone injections, viscosupplementation doesn't work as quickly, but the overall beneficial results are longer-lasting because it enhances rather than restricts the body's natural process of healing.
Viscosupplementation of the Knee: Procedure Snapshot
The doctor will first disinfect the area of injury and usually 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 small space in the joint on one side of the kneecap. Usually rehabilitation exercises to improve muscle strength and mobility are prescribed after treatment.
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.
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.
- Osteoarthritis of the knee. 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.