Outcomes/Effectiveness Research

Evidence of benefit is lacking for many common ways of treating osteoarthritis of the knee

A new scientific review released today by the agency for Healthcare Research and Quality (AHRQ) concludes that evidence of benefit is lacking for many common ways of treating osteoarthritis of the knee, including popular dietary supplement ingredients, a common surgical procedure, and injected preparations.

The review found that glucosamine and chondroitin, over-the-counter dietary supplement ingredients that are used widely because of their purported benefits to relieve knee pain caused by osteoarthritis and improve physical functioning, appear to be no more effective than placebos. A placebo is a harmless substance given to selected patients in a clinical trial that looks like the real drug or injection being studied, but which has no medical effect.

The review also failed to find convincing evidence of benefit from arthroscopic surgery to clean the knee joint with or without removal of debris and loose cartilage. Published studies generally report that injections with hyaluronan preparations (substances that are intended to improve lubrication of the knee joint) improve scores on patient questionnaires used to measure pain and function. However, the evidence is uncertain because of variation in study quality and difficulty determining whether changes in scores translate into real clinical improvements for patients. Osteoarthritis is a widespread, costly disease that wears away the cartilage cushioning the knee joint, causing pain and reducing mobility.

Arthritic diseases, which include osteoarthritis, affect an estimated 46 million people in the United States, and at age 64 and older, one in 10 Americans is estimated to have osteoarthritis of the knee. Osteoarthritis and related arthritic conditions cost more than $81 billion a year in medical care, lost wages, and other expenses.

The authors, who were led by David J. Samson, M.S., associate director of the AHRQ-supported Blue Cross and Blue Shield Association Evidence-based Practice Center in Chicago, reviewed findings from 53 randomized clinical trials of glucosamine, chrondroitin, and injections with hyaluronan preparations and 23 studies of arthroscopy.

The review, which was requested and funded by the Centers for Disease Control and Prevention, scrutinized individual studies concerned with these treatments' effects as well as meta-analyses that analyzed the combined evidence of groups of studies.

According to the authors, better quality randomized clinical trials are needed to clarify whether these treatments are beneficial. However, given the aging of the population and increasing prevalence of obesity—both risk factors for osteoarthritis of the knee—research on new approaches to prevention and treatment of osteoarthritis of the knee should be a high priority.

A copy of Treatment of Primary and Secondary Osteoarthritis of the Knee (AHRQ Publication No. 07-E012) is available from the AHRQ Publications Clearinghouse. The report is also available on AHRQ's Web site at http://www.ahrq.gov/clinic/tp/oakneetp.htm.

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