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. Patients with osteoarthritis (OA) of the knee have lower levels of hyaluronic acid in their synovial fluid. (3) Therefore, their joints are less “greased” and less able to protect the bones and cartilage from damage and destruction. Viscosupplementation, a relatively new but increasingly 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 affected joint.

Viscosupplement Options

The 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.) (6) Today, five viscosupplements are available. Each one is slightly different, but each one is 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 will 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). Unlike all other viscosupplements, 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 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, swelling, and effusion (fluid build-up) around 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. Studies show this viscosupplement can 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 build-up 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. If, after having an injection of a viscosupplement, you begin experiencing closing of the throat, difficulty breathing, hives, or swelling of the lips, tongue, or face, contact your doctor’s office immediately. You may be having a more serious reaction to the injection and need medical attention. 

People with diagnosed egg, bird, poultry, or feather allergies should avoid using most viscosupplement injections, unless tested and approved by your doctor. The hyaluronic acid in these medicines is most often derived from rooster comb, the fleshy crown on top of a rooster’s head. This is true of all viscosupplements with one exception: Orthovisc (high-molecular-weight hyaluronan). This viscosupplement is derived from bacteria and may be a safer option for people with allergies. Euflexxa may also be a safe option for people with egg allergies. Talk with your doctor about your allergies and how this might affect your use of viscosupplements (4).

The Long-term Picture

Viscosupplements are new to the treatment scene—we know how they work in the short-term, but their effectives over longer periods of time is not yet known. Specifically, doctors are uncertain how the use of viscosupplements over a long period of a person’s life will affect the person’s health. (2) Research is also not clear on how viscosupplementation affects the long-term trajectory of OA of the knee. While it does provide some comfort and pain relief for some patients with mild to moderate OA, it may not prevent or even delay the likelihood a patient will need knee-replacement surgery at a later point in their life.