June 2010 Newsletter

Archived Newsletters

Viscosupplementation
By Dr. Stephen A. Hunt

Viscosupplementation is one of the many non-operative procedures that have emerged for the treatment of arthritis. This procedure consists of one or more injections of Hyaluronic Acid (a major component of normal joint fluid) into an arthritic joint. Hyaluronic Acid is a protein that is manufactured by cells in the lining of the joint, called synovial cells. However, in arthritic joints, the concentration of Hyaluronic Acid can be as low as 33-50% of the normal concentration.

Hyaluronic Acid helps joints function normally by providing shock absorbency, joint lubrication, and keeping cartilage well hydrated and nourished. When there is not enough of this substance in a joint, it can significantly impair the joint’s ability to maintain normal function.

Injections of Hyaluronic Acid work by several mechanisms. First, the injections attempt to restore a normal concentration of Hyaluronic Acid to the joint (think a car engine that is low on oil). This boost of lubrication is a temporary effect (lasting a few weeks). Second, the injections stimulate synovial cells to increase the natural production of Hyaluronic Acid (a more lasting effect). Finally, by a little understood mechanism, the injection of Hyaluronic Acid into a joint exerts an anti-inflammatory effect. Additionally, there is recent research that suggests it may help by providing pain relief and protecting cartilage.

There are currently five brands of Hyaluronic Acid injection on the market: Synvisc, Hyalgan, Supartz, Orthovisc, and Euflexxa. All of these have industry-sponsored studies that suggest advantages of one over another, but I am not aware of any truly unbiased clinical trials that demonstrate a clear superiority of one specific brand. The brands differ based on how they are engineered (four being from birds and one from bacteria) and the size of the injections. The number of injections can vary from 1 to 5 during one-week intervals.

The indications for viscosupplementation are mild to moderate arthritis of the knee. It can also be used for multiple joint pain, for example the hip AND knee. Additionally, there are several clinical and basic science trials that suggest viscosupplementation may be helpful for cartilage injuries that are traumatic in nature, such as in an ACL injury in the knee. More evidence is needed before it will be justified to widely use this procedure for these indications.

Viscosupplementation is a relatively safe, non-operative way of treating an arthritic knee. Complications such as infection are extremely rare, but some people have developed an allergic reaction to the injections, which may present like an infection.

Large studies evaluating the effectiveness of viscosupplementation for arthritis of the knee have demonstrated beneficial short-term (3-6 months) outcomes for pain and function versus oral anti-inflammatory medication or steroid injection. In patients with severe arthritis, the beneficial effects are not as significant.

In summary, viscosupplementation provides an alternative treatment for arthritis. You should discuss it with your physician to see if you are a good candidate. Additionally, you may want to check with your insurance, as the injections can be quite costly under certain plans.

REFERENCES:
Strauss, EJ et al. Hyaluronic Acid viscosupplementation and osteoarthritis. Am J Sports Med 2009: 37 (8): 1636-44.