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, which was requested and funded by HHS' Centers for Disease Control and Prevention, 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.
"Millions of Americans seek relief from the pain and reduced mobility caused by osteoarthritis of the knee," said AHRQ Director Carolyn M. Clancy, M.D. "However, they should work with their clinicians to decide the best course of treatment for them based on what has and has not been proven to work."
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.