Hyaluronan Injections for Knee Osteoarthritis

10 Things You Should Know About Hyaluronan

Doctor examining patient's knee
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Hyaluronan injections are a treatment option for osteoarthritis of the knee. Osteoarthritis is a degenerative joint disease which primarily affects cartilage. The ends of the two bones in a normal joint are covered with cartilage, allowing the bones to glide over one another. Cartilage also serves as a shock absorber.

In osteoarthritis, as cartilage wears away, synovial fluid changes and loses its ability to lubricate the joint. Pain, stiffness, and limited range of motion for the affected joint are the result of the deterioration. The treatment which injects hyaluronan into the knee, known as viscosupplementation, is an effort to improve the lubrication of the knee, reduce pain, and improve range of motion. Here are 10 things you should know about hyaluronan injections.

1 - There are currently five hyaluronates approved by the U.S. Food and Drug Administration.

Hyaluronan injections are considered treatments or therapies rather than drugs. Viscosupplementation for osteoarthritis has been studied since the 1970s. In 1997, the first two hyaluronates were approved by the FDA and three more have since been FDA-approved. The list of available hyaluronan injections follows along with their approval dates:

  • Hyalgan - May 28, 1997
  • Synvisc - August 8, 1997
  • Supartz - January 24, 2001
  • Orthovisc - February 5, 2004
  • Euflexxa - December 3, 2004
  • Synvisc-One - February 26, 2009

2 - Hyaluronan is usually not a first line treatment for knee osteoarthritis.

Typically, hyaluronan injections (also sometimes called viscosupplements) are recommended for patients who have not found adequate pain relief from more conservative treatment options:

Although hyaluronan injections are not usually recommended before trying other treatment options, the best result usually occurs if the patient is in the early stages of osteoarthritis. Patients in the later stages of osteoarthritis, who may be waiting for knee replacement surgery, are considered good candidates for hyaluronan injections so they hopefully can get some relief while waiting.

3 - The treatment course for the five types of hyaluronan injections varies.

A complete course of treatment with Synvisc, Orthovisc, or Euflexxa requires three separate knee injections given one week apart. Both Hyalgan and Supartz require five separate injections given one week apart. The injections are given by a doctor or orthopedic surgeon in their office. One or both knees can be injected at the same time. The addition of Synvisc-One to the roster in 2009 made the injections more convenient, requiring just one rather than multiple injections.

4 - How well hyaluronan injections work has been debated.

Clinical studies have concluded that hyaluronan injections can decrease pain and improve function in patients with mild to moderate osteoarthritis of the knee. While some critics balk at that conclusion and suggest the studies were flawed in some way, other doctors believe there is no definitive answer to whether hyaluronan injections are more effective than corticosteroid injections or oral medications. There is no evidence that suggests hyaluronan injections affect the underlying disease course. It is clear that the injections are not a cure.

5 - Among patients who were helped by hyaluronan injections, when pain relief occurred was variable.

The most significant pain relief occurred 8 to 12 weeks after the first injection for most patients. Studies have shown that Synvisc and Hyalgan provide pain relief from knee osteoarthritis for up to six months, with some patients getting relief for an even longer duration. Supartz was shown in studies to provide pain relief for up to 4 1/2 months after the fifth injection.

Patients may be able to repeat the course of treatment with hyaluronan injections. For example, a patient who has experienced up to six months of pain relief from Synvisc but has had pain return may be a candidate for another course of Synvisc injections.

6 - To minimize potential side effects, after an injection patients should avoid strenuous activities for 48 hours.

The most common side effects around the injected joint, which are usually mild, include:

  • temporary injection site pain
  • swelling
  • redness and warmth
  • itching
  • bruising

7 - Hyaluronan injections are only FDA-approved for osteoarthritis of the knee.

Some day, viscosupplementation may be used to treat other joints affected by osteoarthritis. Hyaluronan injections for the shoulder, hip, and ankle are being studied.

8 - The patient does not have to stop other medications they are taking when getting hyaluronan injections.

There should be no adverse interaction with other pain medications or anti-inflammatory medications that a patient is taking.

9 - Both Medicare and private insurance reimburse the cost of medical devices and procedures which are deemed medically necessary.

Currently, Medicare will cover hyaluronan injections for the knee only. Medicare also requires x-ray evidence of the knee osteoarthritis. Medicare will only cover hyaluronan injections if given no sooner than every six months. Private insurance may have different rules so it is always best to check. Always check for Medicare updates too.

10 - There are important safety factors to consider before using hyaluronan injections.

Patients wishing to try Synvisc, who are allergic to bird products (i.e., feathers, eggs or poultry), should talk to their doctor. Patients should also make their doctor aware of legs which are swollen or infected. Also, hyaluronan injections have not been tested in children, pregnant women, or nursing mothers.

View Article Sources
  • What Is Viscosupplementation? Cleveland Clinic. 7/28/2007.
  • Recommendation for the Medical Management of Osteoarthritis of the Hip and Knee. American College of Rheumatology. 7/26/2007.