WEDNESDAY, Sept. 10 (HealthDay News) -- Arthroscopic surgery to relieve osteoarthritis of the knee, a widely practiced procedure, proves no better than medicine and physical therapy alone, new research shows.

This is the second major study to call into question the benefits of the surgery, and it may well influence how patients are treated.

"There's going to be a swing in practice," said Dr. Brian Feagan, co-author of a study in the Sept. 11 issue of the New England Journal of Medicine (NEJM).

Fortunately, there are still considerable options available for the 27 million people in the United States who suffer from the condition.

"In this trial, both groups had optimized medical therapy, and both groups did not do too badly," added Feagan, director of Robarts Clinical Trials at the Robarts Research Institute at The University of Western Ontario in London, Ontario, Canada. "For severe disease, total joint replacement is a very effective form of therapy. This study de-emphasizes the middle step of arthroscopic surgery."

Other experts, however, say it would be a mistake to dismiss arthroscopy all together for arthritis.

"Arthroscopic surgery does not work well for patients with arthritis, but it does work well in certain select patients who do have arthritis but who also have another problem like torn meniscus [the area where the major bones of the leg connect]," said Dr. Robert Marx, author of an accompanying editorial and an orthopedic surgeon at New York City's Hospital for Special Surgery. "The classic example would be a patient saying their knee was hurting for five years, but three months ago, they stepped off a curb, and since then, it's been killing them. It's a different pain from the arthritis. . . . If we put it all together, there's a good chance with surgery, but we do need to temper their expectations."

"There's definitely still a role for arthroscopic treatment in arthritic knees, but it's really specific," said Dr. Robert Reeve, an assistant professor of surgery at Texas A&M Health Science Center College of Medicine and director of the Division of Sports Medicine at Scott & White in Temple. "I think it's still useful for major meniscal tears but . . . [there is] good evidence that it's not very effective for arthritis or minor degenerative tears. There's still a role for arthroscopy in treating arthritic knees if there's a significant meniscus tear and the symptoms are consistent with that tear. The symptoms have to match the MRI."

"If patients have severe arthritis that fails nonoperative treatment, then they may benefit from a total knee replacement rather than arthroscopic surgery, Marx added.

Since its debut some three decades ago, arthroscopic surgery has evolved from an experimental procedure to a mainstream practice without undergoing rigorous evaluation, Feagan noted.

The minimally invasive procedure involves inserting small instruments, including an arthroscope, into the knee through tiny incisions. Surgeons then "scrape" the joints to remove cartilage and smooth the surfaces of the joints.

In 2002, a study also published in the NEJM found similar results, but the orthopedic community remained unswayed.

"It really didn't change practice that much," Feagan said. "That's why this second [study] was really important."

This randomized, controlled trial involved 178 patients, average age 60. Half were randomized to receive arthroscopic surgery along with medical and physical therapy, the other half to medical and physical therapy alone. All had moderate-to-severe osteoarthritis of the knee.

After two years, both groups' scores on a measure of arthritis severity were about the same, with individuals in both groups experiencing improvement in symptoms.

A second study also published in the same journal issue, found that meniscal tears are common in the general population and may not, in fact, be responsible for painful symptoms.

The U.S. and Swedish authors suggested that meniscal tears detected on MRI may actually confuse matters and lead to unnecessary therapy. Further complicating matters is the fact that meniscal tears are also often associated with osteoarthritis of the knee.

• More News on Knee Injuries and Disorders
• More News on Osteoarthritis

Related MedlinePlus Pages:

• Knee Injuries and Disorders
• Osteoarthritis