Sodium hyaluronate injections are an accepted form of treatment for osteoarthritis affecting the knee. More recent evidence supports its use for osteoarthritis affecting the shoulder, hip, base of the thumb, and ankle.
Sodium hyaluronate is injected by the physician directly into the joint, where it may help supplement the joint’s natural synovial fluid, leading to pain relief and improved functioning in the joint. This treatment is also called viscosupplementation to describe its proposed mechanism of action.
Treatment includes 3 to 5 shots into the joint over 3 to 5 weeks. Examples of sodium hyaluronate preparations include Hyalgan, Supartz, Synvisc, Euflexxa, and Orthovisc.
The joint needs to undergo sterile preparation before administering the medication. Anesthesia of the skin using lidocaine is recommended since the needle required to inject the viscosupplement is a fairly large bore needle.
In addition, it is important that either ultrasound or fluoroscopy be used to administer the viscosupplement into proper location. Examples of injection of the drug into the fat pad of the knee causing a severe inflammatory react6ion are not uncommon when an imaging modality is not used.
After an injection, some people may experience pain or swelling. The use of certain viscosupplements such as Synvisc have been associated with “pseudoseptic” reactions. These consist of marked swelling and pain accompanied by low grade fever. The fluid that is aspirated from the joint has a high white cell count. It is suspected that at least some of these reactions are due to inadvertent fat pad injections.
Doctors use sodium hyaluronate (hyaluronic acid) to treat osteoarthritis that has not improved with other more conservative measures such as analgesics (pain relievers like acetaminophen), non-steroidal anti-inflammatory drugs (NSAIDs), steroid injections, and physical therapy.
Results of some studies have shown that hyaluronan injections have improved the symptoms of osteoarthritis and joint function in some people. Results in other studies have been inconclusive about the effectiveness of hyaluronan injections. The consensus among practicing physicians is that hyaluronan injections are helpful.
Hyaluronan injections may cause pain or swelling. Since hyaluronans are often derived from bird products, it is important to tell your physician if you are allergic to birds, feathers, or egg products.
Series of sodium hyaluronan injections can be repeated as often as every six months.
