In a study of 180 patients with osteoarthritis of the knee, Houston surgeons found that those who received "sham" arthroscopic surgery reported as much pain relief and improved mobility as patients who actually underwent the procedure.

In fact, the group that did not receive surgery reported better short-term functioning compared with the other patients.

It has been unclear why arthroscopic surgery for knee osteoarthritis helps some people with the condition. Dr. Moseley and his colleagues at Baylor College of Medicine, in Houston, decided to test whether arthroscopic surgery might be associated with a placebo effect.

After 2 weeks, patients assigned to sham surgery were doing better than the true surgery patients -- probably, Dr. Moseley said, because they had been spared the trauma of surgery. After 2 years, the groups had made similar gains in walking and stair climbing, and their pain had eased to comparable degrees.

Because all patients received pain-killing drugs and none underwent physical therapy after their actual or sham surgery, Moseley credited the placebo effect for helping the sham-surgery group. "I was surprised," he said, noting that when colleagues first proposed the possibility to him, he discounted it.

While this research is not the final word on arthroscopic surgery for knee arthritis, Dr. Moseley said it does suggest it may be time for surgeons to take a closer look at it.

"We, as surgeons," he said, "may need to put our time into finding better and more effective treatments."

Annual Meeting Of The American Academy of Orthopedic Surgeons San Francisco March 1, 2001