Study Doubts Knee Surgery Benefits

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Ted Horowitz / Corbis

Doctors perform arthroscopic surgery on a patient's knee.

One of the most commonly used surgical procedures aimed at easing the pain of arthritis in the knee works no better than noninvasive therapy or drugs, according to a new study reported this week in the New England Journal of Medicine. At best, the study's authors say, the short-term relief reported by some surgery patients may simply be a placebo effect, and for millions of arthritis sufferers, surgery does not easy stiffness or pain any better than physical therapy or anti-inflmmatory drugs.

The same message went out to orthopedic surgeons in 2002, when a study of U.S. veterans found that patients who got arthroscopic knee surgery did not fare any better than patients who were given "sham surgery" but led to believe they had undergone a real procedure. That study, conducted by Department of Veterans Affairs (VA), prompted Medicare to drop coverage of the procedure for osteoarthritis patients. But whether it actually impacted the vast numbers of knee surgeries being done in the U.S. is debated: Some experts believe many surgeons now tweak their diagnoses on insurance forms to meet Medicare requirements (the surgery is covered for other conditions, but not osteoarthritis); others disagree. Critics also rejected the VA study findings in part because they said the study's investigators did not define their patient group carefully enough. Not all the veterans had comparable conditions; some, for example, had bow legs.

The new study, conducted by Canadian researchers, reinforces the VA findings. About 20% of the 900,000 arthroscopic knee surgeries performed annually in North America are done as treatment for osteoarthritis, according to the study's co-author Dr. Bob Litchfield, the medical director of the Fowler Kennedy Sport Medicine Clinic at London Health Sciences Centre in Ontario, Canada. But he concedes that those numbers are disputed by some of his colleagues who say the VA study did have an impact in reducing surgeries for that condition. The vast majority of all arthroscopic knee surgeries — which involve inserting a miniature scope and camera into the knee through a tiny incision, then flushing away bone chips and smoothing rough cartilage in the joint — take place in the U.S., despite Medicare limitations on reimbursement. (Canadian doctors account for about 10% of the surgeries performed, primarily because of the surgical waiting lists in Canada, which force surgeons to prioritize their procedures by importance.)

The Canadian study, which ran from 1999 to 2007 and included patients of orthopedic surgeons, rheumatologists and physiotherapists, sought to address some of the concerns raised about the 2002 report: The new study includes a better defined, but more diverse and representative, group of patients, and measured success using a carefully calibrated index that assessed patients' pain, stiffness and physical function. A group of 178 men and women from the London, Ontario, area with an average age of 60 were divided into two groups — half received knee surgery and a regimen of physical therapy and medications, as needed; the other half received only the physical therapy and medication.

The two groups were carefully balanced for age, obesity and gender, Litchfield said, and their conditions were narrowly focused on osteoarthritis. In most cases of arthritis of the knee there is some evidence of damage to the miniscus, the cartilage that cushions the knee joint, says Litchfield, but some tears are too small to show up on X-rays or MRIs prior to surgery. The study eliminated all patients with discernible miniscal tears, on the assumption that they would clearly benefit from surgery. (A separate paper published in the same issue of the New England Journal of Medicine found, however, that meniscal tears may have no impact on arthritis pain: Two-thirds of middle-aged and elderly people in the study who had a damaged meniscus reported no pain or stiffness.)

Litchfield's study found that three months after arthroscopic surgery, patients appeared to enjoy no additional benefit compared with the nonsurgical group, suggesting that the operation initially may have had a placebo effect. Both groups experienced some improvement, which Litchfield credits in part to the structured regimen of physical therapy, home exercise and diligent follow up by nurses.

"Those who take some ownership for recovery, rather than just showing up at the surgeon's office and saying, 'Fix me'" have a better outcome, Litchfield says.

The study also suggests that the age of the patient, the cause of the injury and the origin of the pain should be taken into consideration when assessing whether surgery is necessary. The procedure is appropriate in patients with arthritis but only where the osteoarthritis is not the primary cause of pain. Even in those cases, patients whose X-rays already show arthritis have the least to gain, Litchfield says. Younger patients whose X-rays show minimal arthritic changes have the most to gain.

While knee surgery is a very safe operation, there are risks that patients should consider, Litchfield says. In about five percent of cases patients may develop infections or phlebitis. The bottom line, drawing on this study, is that in patients whose X-rays show that arthritis alone is the cause of their pain, arthroscopic surgery "should be used very judiciously," Litchfield says. It remains to be seen whether orthopedic surgeons and patients who want that quick fix will heed the advice.