Joint Lubricants or Viscosupplements

Knee arthritis is among the most common causes of knee pain. When the smooth cartilage of the knee joint wears thin, pain in the joint is often the result. Treatment of knee arthritis is focused on trying to relieve pain while keeping treatments as simple as possible. The non-operative treatments of knee arthritis are focused on the reduction of pain, primarily with the use of anti-inflammatory medications, activity modifications, ambulatory aids, and cortisone injections.

Unfortunately, these treatments may not be sufficient for relieving the discomfort in all patients. When non-surgical treatments fail to provide adequate relief, a knee replacement surgery may be considered. Knowing when the timing is right to have a knee replacement can be a difficult decision to make. Joint lubrication injections are a treatment that is intended to relieve the symptoms of knee arthritis and delay the need for knee replacement surgery.

Knee injection / Getty Images

How Do Joint Supplements Work?

Viscosupplementation is an injectable medication called hyaluronan. Injectable hyaluronan is often referred to by its most commonly known brand name of "Synvisc." Other brand names of hyaluronan include Orthovisc, Euflexxa, and Supartz.

Joint lubricant shots typically administered as a series of three injections into the knee joint, each injection spaced about one week apart. Sometimes a larger does of these medications can be administered in a single injection, such is the case with Synvisc One injections.

Hyaluronan, the name of the substance in viscosupplement injections, is present in normal joint fluid and responsible for the lubricating properties of normal joint fluid. The lubricating effects of joint fluid allow for the cartilage surfaces of joints to glide upon each other in a smooth fashion. By injecting the medication into a knee joint, some people consider this a so-called joint lubrication. This is why you may hear of viscosupplements as a 'motor oil' for the knee joint. Hyaluronan has also been shown to have anti-inflammatory properties and may help protect remaining cartilage in the joint.

Does It Help?

Numerous studies have investigated the effectiveness of various viscosupplements as a treatment for knee arthritis. Studies have ranged in their results from no benefit when compared to placebo injections, to mild improvement in symptoms. However, the larger, better-designed studies seem to show very little benefit with these injections.

Initially, there was great hope that these joint lubricants would be effective for relief of knee arthritis symptoms. Smaller studies seemed to show some small benefit to patients, and therefore the injections started to become popular. Unfortunately, larger studies did not show this effect. Of particular importance, is that when studies were blinded (so that neither patients nor healthcare providers knew which treatment--viscosupplement or placebo--was in the syringe) the effects were negligible.

Should You Have Injections?

So where does this leave patients? No study has shown that joint lubrication injections are an effective treatment in a large number of patients over a long period of time. The early interest in these shots was based mostly on smaller studies that were not well designed.

On the other hand, many patients will swear these injections have helped them, and there is little downside to the injections. No study has found serious adverse side effects associated with the use of joint lubricant injections in the knee joint. When reactions to viscosupplement injections occur, they tend to be flare-ups of knee inflammation, that usually settle down within a few days.

Many insurance companies have begun to deny coverage of viscosupplement injections because of their lack of clinical effectiveness. However, if you are interested in the injections, you should discuss with your healthcare provider if they may be a reasonable treatment to try to find relief from knee arthritis.

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By Jonathan Cluett, MD
Jonathan Cluett, MD, is board-certified in orthopedic surgery. He served as assistant team physician to Chivas USA (Major League Soccer) and the United States men's and women's national soccer teams.