What Is Viscosupplementation?
Hyaluronic acid is a naturally occurring substance present in the synovial fluid of your joints. In your knees, synovial fluid, a thick gel-like liquid, helps cushion your joint and absorb the shock of walking, running, twisting, and turning. People with osteoarthritis (OA) of the knee have lower levels of hyaluronic acid in their synovial fluid. Therefore, their joints are less “greased” and less able to protect the bones and cartilage from damage and destruction. Viscosupplementation, a popular treatment for OA of the knee, injects hyaluronic acid (also called hyaluron and hyaluronate) into the affected knee in order to hopefully return some mobility to the joint.
The U.S. Food and Drug Administration (FDA) first approved prescription viscosupplements in 1997, to treat mild to moderate OA of the knee. (The FDA has not approved viscosupplementation for treatment of OA in any other joint in the body.) There are several viscosupplements available today. Each one is slightly different, but they’re all designed to help people looking to treat the signs and symptoms of OA find relief.
The viscosupplement options include:
Euflexxa (sodium hyaluronate)
Euflexxa is given as a three-dose injection over three weeks (one injection per week). The average patient may experience relief from a series of Euflexxa injections for six months. The most common side effects of a Euflexxa injection are pain at injection site, skin irritation at injection site, swelling of the knee, and tenderness around the joint.
Hyalgan (sodium hyaluronate)
Hyalgan was the first viscosupplement approved by the FDA in 1997. This viscosupplement is given as a series of five injections, once per week for five weeks. The most common side effects of a Hyalgan injection include pain at the injection site, itching, swelling around the joint, redness or bruising at the injection site, and headache.
Orthovisc (high-molecular-weight hyaluronan)
Orthovisc is derived from bacterial cells, not rooster combs. This makes it an ideal option for OA patients with sensitivities or allergies to birds or chickens, eggs, and feathers. Orthovisc is available as a three- or four-dose injection. The most common side effects of an injection of Orthovisc include swelling around the joint and a rash or bruise at the injection site.
Supartz (sodium hyaluronate)
This viscosupplement is given as a three- or five-dose injection. A three-dose injection series provides relief for up to six months. A greater number of injections may provide a longer window of pain relief. The most common side effects of a Supartz injection include pain, effusion (swelling in the joint), redness and bruising at the joint, and injection site pain.
Synvisc-One (hylan G-F 20)
Synvisc-One is the only viscosupplement approved as a one-dose injection. The FDA indicates that this viscosupplement is designed to provide up to six months of OA relief after just one injection. The most common side effects of a Synvisc-One injection include swelling around the affected joint and pain and stiffness in the joint.
Synvisc (hylan G-F 20)
Unlike Synvisc-One, Synvisc requires three injections of hyaluronic acid. The effects of the injection can last as long as six months. The side effects of Synvisc are similar to the side effects of Synvisc-One — pain, swelling, and fluid buildup around the affected joint.
The More Serious Side Effects of Viscosupplements
Typical side effects of viscosupplement injections are mild — redness, swelling, skin irritation at the injection site — but serious side effects are possible. Contact your doctor’s office immediately if you begin experiencing any of the following side effects:
- closing of the throat
- difficulty breathing
- swelling of the lips, tongue, or face
You may be having a more serious reaction to the injection and need medical attention.
Talk with your doctor about your allergies and how this might affect your use of viscosupplements.
The Long-Term Picture
Viscosupplements are new to the treatment scene. We know how they work in the short term, but their effectiveness over longer periods of time isn’t yet known. Specifically, doctors are uncertain how the use of viscosupplements over the course of a person’s life will affect health. Research is also not clear on how viscosupplementation affects the long-term trajectory of OA of the knee. While it does provide comfort and pain relief for some people with mild to moderate OA, it may not prevent or even delay the likelihood that a patient will need knee replacement surgery at a later point in their life.