NEW YORK (Reuters Health) - New research suggests that the minimally invasive procedures commonly used to treat knee arthritis may have no real effect on patients' pain and mobility.

Investigators found that the procedures--arthroscopic debridement and arthroscopic lavage--were no better than a "sham" operation in relieving knee arthritis symptoms among 180 patients.

That's not to say that patients didn't feel better after arthroscopic surgery--they just didn't feel any better than those who got so-called placebo surgery, the study's lead author told Reuters Health.

"Patients do feel better, but this (study) would suggest it's the placebo effect," said Dr. Nelda P. Wray of Baylor College of Medicine in Houston, Texas.

According to Wray, the findings question whether the risk--albeit small--and the not-so-small cost of the two procedures are worth it.

She and her colleagues report their findings in the July 11th issue of The New England Journal of Medicine.

Osteoarthritis occurs when the cartilage that cushions joints breaks down, often leading to pain, swelling and loss of mobility. An estimated 12% of Americans aged 65 and older have osteoarthritis of the knee. When drugs and other measures such as exercise fail to work, patients are commonly referred for arthroscopic lavage or debridement. About 650,000 such procedures are performed in the US every year, at a cost of about $5,000 per procedure.

The belief has been that, because the procedures remove loose cartilage and other "debris" that mark arthritic joints, they may improve patients' pain and functioning. Lavage involves flushing the knee joint with fluid, while debridement goes further--along with lavage, damaged tissue fragments are trimmed and the area is smoothed. Both are performed through small incisions, using fiber optics to allow surgeons to view the inside of the joint.

But whether such debris clean-up truly helps patients has been unclear. For one, Wray said, experts don't really know where the pain of osteoarthritis comes from. She noted that some people with severe joint damage don't have serious pain, while others with mild joint degeneration do.

So Wray's team looked at the possibility that patients who have improved after knee lavage or debridement owe the benefits to the placebo effect--a psychological lift that helps patients feel better physically.

Study patients underwent either lavage, debridement or a placebo procedure, in which the surgeon made tiny, skin-deep incisions around the knee but did nothing inside the joint. The researchers found that "at no point" over the next 2 years did patients who received the actual surgery report less pain or better functioning than the sham-surgery patients did.

Wray noted that there are ethical concerns in using sham procedures in studies, the central issues being whether patients are fully informed that they may have a placebo surgery that will not benefit them, and whether the procedure risk is "as low as possible"--both of which, according to Wray, were assured in this study.

Moreover, the researcher said it now looks like arthroscopic lavage and debridement for arthritis may be placebo procedures themselves.

Wray suggests that the medical field needs to "reconsider" whether the risks of the procedures--including the relatively low odds of infection or blood clots--and the "billions" spent on them annually in the US are worthwhile.

An accompanying editorial also doubts the benefits of lavage and debridement. Drs. David T. Felson and Joseph Buckwalter write that while removing debris from the arthritic knee "may sound appealing," it seems that "larger forces" like muscle weakness, instability and obesity are more important in how knee-arthritis patients fare.

Felson, of Boston University in Massachusetts, and Buckwalter, of the University of Iowa in Iowa City, note that in past research with no "sham treatment," patients who had lavage or debridement did report greater improvement in knee pain than untreated patients.

But, they write, "it...seems clear that sham controls are needed" to accurately judge the two procedures.

SOURCE: The New England Journal of Medicine 2002;347:81-88, 132-133.

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