Labos: How new data cast doubt on an old surgery

In medicine, many treatments that seem logical and plausible don’t end up working when tested in patients. That almost counterintuitive fact is what spawned the evidence-based medicine movement of the 1990s. It was only in the past 30 years that we systematically started testing whether something did work rather than simply assuming that it should work.

Case in point, surgically removing or trimming back a torn meniscus seems to make a ton of sense. But when it was ultimately tested in a randomized controlled trial, it had no benefit.

The meniscus is a crescent shaped piece of cartilage in your knee that serves as a sort of shock absorber for the joint. It can be damaged with twisting motions but can also degenerate without any acute trauma. The pain caused by meniscal tears may be hard to differentiate from arthritis pain or a torn ACL, and nothing stops both problems from existing simultaneously in the same patient.

Back in the day, meniscectomies were very common. Arthroscopic or keyhole surgeries of the knee to remove or cut away the meniscus were once one of the most common surgical procedures. A 2006 report found approximately 700,000 such surgeries were performed annually in the U.S. at a cost of about $4 billion.

Given the cost associated with this procedure, you would have thought that the surgery had been rigorously tested before being broadly applied. But for much of medical history, expert opinion and common sense ruled the day.

Only in 2013 did data suggest the surgery was ineffective. One study tested physical therapy plus surgery versus physical therapy alone in patients with a meniscal tear and osteoarthritis of the knee. Six months out, there was no difference between the groups, which suggests the surgery added little to the patients’ functional recovery (although many of the patients randomized to physical therapy alone ultimately got surgery down the road.)

Much more definitive was the FIDELITY study published in the same year. The patients in this study had meniscal tears but no arthritis, so no other pathologies were confounding their symptomatology. They were randomized to surgery or a sham surgery, the interventional equivalent of a placebo controls.

With medications, making a placebo is easy. All you need is a pill that looks, feels and tastes the same so that patients and their doctors cannot tell the difference. Surgeries are more complicated as patients obviously know if you cut into them or not. The only way for a true controlled trial is for a placebo procedure or sham surgery, where the procedure is simulated but the meniscus is left in place.

Sham surgery trials are rare but necessary because otherwise you never completely account for the placebo response. In cardiology, renal denervation was set to become a game changer in treating resistant hypertension as multiple studies showed that the procedure reduced blood pressure. But then the SIMPLICITY HTN-3 trial performed used a sham surgery control and found patient’s blood pressure just as much regardless.

The FIDELITY study proved just how potent the placebo response can be. Compared to a sham procedure, meniscus surgery conferred no benefit. Recently, the authors published their 10-year follow-up data, which confirmed no long-term benefit to the surgery. If anything, the surgical group did worse than the sham surgery group in terms of pain symptoms. An attempt to alleviate patient’s symptoms might have been making thing worse all along.

Over the past decade, the frequency of meniscectomies has been decreasing for exactly this reason. The data did not support what had been standard practice for years It made a ton of sense that when you saw a torn meniscus, you should take it out. But in fact, it’s probably better to leave it in.

Christopher Labos, Special to the Montreal Gazette

Christopher Labos is a Montreal physician. He’s the host of The Body of Evidence podcast and the author of Does Coffee Cause Cancer?

The post Labos: How new data cast doubt on an old surgery appeared first on Montreal Gazette.