Viscosupplementation: An understanding of the treatment, options available, potential side-effects and the long-term view

Hyaluronic acid naturally occurs in the synovial fluid of joints. In the knees, a thick gel-like liquid known as synovial fluid cushions the joint and helps absorb the shock of jogging, running, walking, twisting and turning. People suffering from knee osteoarthritis (OA) have less hyaluronic acid in their synovial fluid. That is why their joints are less ‘greased’ and are able to protect the cartilage and bone from any kind of damage or destruction. Viscosupplementationis a popular method of treating knee osteoarthritis that works by injecting hyaluronic acid (also known as hyaluronate and hyaluron) into the afflicted knee to return some kind of mobility to the joint. The main objective of adding hyaluronic acid to the joint fluid in an arthritic knee is to –

• Facilitate greater knee movement
• Reduce the patient’s pain
• Slow the progression of osteoarthritis as much as possible

Hyaluronic acid acts as a natural lubricant allowing bones to smoothly move over each other and act as a kind of shock absorber. The theory is that adding hyaluronic acid to an arthritic joint should facilitate movement and reduce a patient’s pain. Typical candidates who are recommended viscosupplementation are knee osteoarthritis patients who have failed to improve with other non-surgical treatment methods. After the injections, patients are advised to take part in a rehabilitation program that involves gentle progressive knee exercise. The main purpose of this is to develop muscle strength and improve the range of motion required for knee support.

Viscosupplement options

Several commercial preparations of hyaluronic acid are now available in the market. Each one is slightly different, but all are meant to assist people looking to treat OA signs and symptoms. Some of the options are –

1.      Hyalgan – Hyalgan was the first viscosupplement given approval by the FDA. Hyalgan is given in a course of five injections, once a week for five weeks. Common side effects reported by patients after a Hyalgan injection include itching, joint swelling, redness or pain at the injection site and a headache.

2.      Euflexxa – Euflexxa is given over three weeks as a three-dose injection (i.e. one dose per week). The average time that a patient can expect to experience pain relief with Euflexxa injections is six months. Common side effects of Euflexxa injections are skin irritation, knee swelling, joint redness and some tenderness.

3.      Orthovisc ­– Orthovisc is created from bacterial cells and not rooster combs. Thus, it is perfectly suited for OA patients who might have some kind of bird, egg or feather allergy or sensitivity. Orthovisc is available in either a three or four dose injection. Side effects include joint swelling and a rash at the injection site.

4.      Supartz – Available in a three or five dose injection. The former provides pain relief for up to six months. A longer pain relief window is provided with a greater number of injections. Common side effects are injection site pain, joint effusion, and redness at the joint.

5.      Synvisc-One ­– Synvisc-One is the sole viscosupplement administered in one dose. The FDA is of the opinion that Synvisc-One can provide six months relief after a single injection. The main side effects are joint swelling, pain and stiffness.

Major side effects 

On occasion, major side effects are possible with viscosupplement injections. Some examples are closing of the throat, hives, difficulty breathing and lip, tongue or facial swelling. This could be an adverse reaction to the injection that requires urgent medical attention. Patients are advised to talk to their doctors about how their allergies could potentially affect their viscosupplement usage.

Long-term view

Viscosupplements are a relatively new method of treatment. While the short-term effects are well documented, the long-term effects are unknown. Doctors are unsure how prolonged use of viscosupplements will affect a patient’s health over an extended period of time. Recent research on viscosupplementation has not found it to be 100% effective at improving joint function or significantly reducing pain. While some patients claim to feel better with the procedure, others do not seem to have been helped by hyaluronic acid injections. Viscosupplements might not even be able to entirely prevent the possibility of a person requiring knee replacement surgery at some point in the future. Additional research on viscosupplementation and its long term effects are ongoing and might be able to definitely answer this question once and for all.