Arthroscopic surgery is no better than conservative treatment for people with knee osteoarthritis. This was shown in a 2002 clinical trial, and now a new trial has produced the same result. Will it change anything? Will people be told that surgery provides no advantage over drug treatment and physical therapy? Are there any exceptions?

These are just a few of the questions raised by two studies published in The New England Journal of Medicine. The backstory for their findings are the advances in fiberoptics and instrumentation that have made knee procedures much easier and safer to perform than an open-incision operation. And advances in imaging, specifically MRI scans, can mislead doctors into seeing a tear in the knee cartilage as reason enough to perform surgery for someone with knee pain. Add the lack of any requirement for scientific proof that an operation is effective before it becomes widespread. And what Americans get as a result is a lot of unnecessary knee surgery.

Sometimes referred to as “keyhole surgery,” arthroscopic surgery involves a small incision in the knee, which is inflated with fluid under pressure with a pump. This allows the surgeon to work through an arthroscope, flushing out material (lavage), such as cartilage fragments, and scraping the rough surfaces of the arthritic knee joint to remove debris (debridement).

The new trial randomly assigned 178 men and women to receive the operation or conservative treatment alone. All were treated at a sport medicine clinic at the University of Western Ontario, Canada; all had moderate-to-severe osteoarthritis of the knee. All, including those assigned to surgery, received 12 weeks of physical therapy, drug therapy advice, and were free to try any other non-surgical treatments, such as lubricant or steroid injections.

At two years of follow-up, the Canadian researchers concluded, “The people assigned to arthroscopic surgery were no more likely to improve with respect to physical function, pain, or health-related quality of life than were those assigned to the control group [no surgery].” The Canadian Institutes of Health Research funded this trial.

Its findings should settle a controversy that followed a 2002 American trial that also found knee surgery offered no advantage over the usual non-surgical care. Although many people experienced symptom relief after knee surgery, some orthopedic surgeons had long suspected that the operation did not work. In one of a few clinical trials to show that surgery can have a placebo effect, researchers at the Veterans Affairs Medical Center, Houston, TX, randomly assigned 165 men with knee arthritis to receive either knee surgery or a sham procedure.

Those assigned to the sham procedure were taken to the operating room, lightly sedated and given an incision similar to the one made during arthroscopic surgery. This allowed all participants to remain unaware of their actual treatment until two years later—after they had had their symptoms and knee function regularly assessed. Those given the sham procedure had the same level of pain relief and physical function as those given surgery. Whether this study led to a decline in knee surgery is unknown because there is no national system for keeping track.

Predictably, many orthopedic surgeons rejected the 2002 findings, charging that the trial was flawed. For example, only one surgeon had performed all the operations and the participants were all men who were older than the typical knee surgery patient. The Canadian trial was designed specifically to overcome these and other criticisms.

MRI of the Knee

Another study published in the same issue of The New England Journal of Medicine found that a tear in the knee cartilage is present on a MRI scan of most middle-aged and elderly people who have no knee symptoms. This finding has major implications because doctors often order magnetic resonance imaging for people with knee pain of unknown cause. And when a tear in the knee cartilage (meniscus) is found, it is often assumed to be the cause, especially in people with knee osteoarthritis. Repair of the meniscus, which is the small portion of the cartilage that helps stabilize the knee, is a common reason for arthroscopic knee surgery. (About 80% of the people in the Canadian trial had degenerative meniscal tears.)

The MRI study participants were living in Framingham, Massachusetts, when they were randomly selected from census data and random-digit telephone dialing. MRI scans were performed on the right knee of 991 male and female participants. All were asked to fill out questionnaires about possible knee symptoms. Of the participants who reported “knee pain, aching or stiffness on most days,” 63% had meniscal tears on the MRI. Of those who reported no knee problems, 60% showed meniscal tears on the MRI.

In an editorial that accompanied this MRI study and the Canadian trial, Robert G. Marx, MD, observed that the latter had excluded people with large meniscal tears from participation because there still is a role for knee surgery for this injury. In a telephone interview, Dr. Marx, an orthopedic surgeon at New York City’s Hospital for Special Surgery, was asked how a “large” meniscal tear is determined and how the consumer would know whether it is large enough to warrant surgery. “It’s not so simple,” he responded. “It is determined by the surgeon who takes all variables into consideration, such as the patient’s history, the physical exam, the x-ray and the MRI before recommending surgery.”

A co-author of the Canadian trial, Brian G. Feagan, MD, University of Western Ontario, strongly disagreed with Dr. Marx’s diagnostic advice but was in total agreement that large meniscal tears require surgery. “Large meniscal tears are not difficult to diagnose with a physical examination because the patient will have substantial locking of the knee,” said Dr. Feagan in a telephone interview. “It is usually seen in younger people with sports injuries and you you don’t need an MRI scan. No one would deny that surgery is effective for people with locking of the knee due to a large meniscal tear, but the vast majority of people do not have large tears, they get meniscal tearing, which is actually meniscal degeneration.”

Referring to the MRI study, which was published along with his arthroscopic surgery trial, Dr. Feagan emphasized, “That study showed that there is no correlation between those small tears seen on an MRI scan and clinical symptoms, so it doesn’t make sense to repair them because they don’t cause any symptoms in the first place.”

Asked for the take-home message of his study, Dr. Feagan replied, “The majority of the patients with mild to moderate osteoarthritis of the knee will do reasonably well with drug therapy and physiotherapy. And total knee joint replacement is excellent for people with severe disease.”

Maryann Napoli, Center for Medical Consumers ©

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