Operating theatre – camera, lights and action

Sham knee surgery suggests one of the most common orthopaedic procedures could be unnecessary. Adam Jenney reports.

A surgeon inserts an arthroscope into a patient's knee joint. The instrument is used to view inside the joint via a video screen. – SPL Creative / Getty

One of the most common orthopaedic procedures – keyhole surgery to repair part of the knee joint – could be unnecessary in many cases, a recent study suggests.

Finnish orthopaedic surgeon Raine Sihvonen, from the University of Tampere, and his colleagues devised an unusual experiment. They recruited doctors to pretend to operate creating a “surgical placebo”. The researchers then compared recovery rates between those who had the real operation and those who went through the sham procedure.

Their findings, published in the New England Journal of Medicine, suggest many people could avoid surgery altogether for ordinary wear and tear.

Peter Choong, head of orthopaedics at St Vincent’s hospital in Melbourne and professor of surgery at the University of Melbourne, says the research calls into question whether the operation is appropriate for degenerative tears in patients who have had symptoms for 10 months or more.

“The research is a valuable contribution. But what is not clear is whether a concerted physiotherapy program … would have drawn a difference,” Choong said. “It would also have been interesting to know if the consumption of over-the-counter painkillers was the same for the two groups in the short term.”

Keyhole knee surgery for osteoarthritis is not a panacea and several
trials have questioned its effectiveness.

While the surgery may have been a sham, the complaint that was being investigated is not. The medial meniscus is a half-moon-shaped band of cartilage in the knee joint that acts a shock absorber. Through age and injury, it can fray or tear with painful, debilitating consequences.

Repairing the meniscus used to involve cutting the knee open and pulling the bones apart – a major operation. These days, with an arthroscope – a tiny tube-mounted camera – to guide the surgeon through small incisions, repairing ragged cartilage is a relatively minor procedure. It is now performed 700,000 times a year in the US alone at an estimated cost of US$4 billion.

But keyhole knee surgery in many cases, such as osteoarthritis, is not a panacea and several trials have questioned its effectiveness. Sihvonen was inspired to take a closer look.

He and his team took 160 adults aged between 35 and 65 diagnosed with meniscal degeneration. All went to the operating theatre where the surgeon performed an arthroscopy, which involved making a tiny incision, injecting some fluid, and inserting the tube-mounted camera into the knee. This confirmed that 146 of the 160 patients had meniscal tears. Then the play-acting began with 70 chosen at random for keyhole surgery and 76 for the sham.

Arthroscopic view of meniscus
An arthroscopic view of a tear in the medial meniscus of the knee. The cartilage reduces friction and acts as a shock absorber. – SPL Creative / Getty

But the sham operation had to look like the real thing and the result was pure theatre. The surgeon manipulated the leg as if for the true operation and took the same amount of time. Most patients were conscious since they received only a spinal anaesthetic, so it had to sound like a real operation too. The doctors used instruments such as the cartilage shaver inserted into the knee with no blade. Only the operating room staff knew which cases were genuine and which were fake.

The deception went on during recovery. All patients were given the same post-operative instructions and care but none of the clinical assessors or researchers who followed up the patients for 12 months knew which patients had received real versus sham surgery. Both groups had the same incision on their knee as a result of the initial arthroscopy, so there was no give-away to the patient or after-surgery carer.

Remarkably, at the end of that period both groups showed considerable improvement. There was no significant difference in pain or function between the operated or sham after 12 months as measured by responses to several questionnaires. However, Choong points out that the study showed some benefits of the operation in the shorter term. “There appeared to be symptom-relief in the first three months following the arthroscopy that was better than in sham controls,” he said.

So why had both groups improved so much after a year? Had the manipulation itself, even without the surgery, been enough to cause an improvement?

“Unfortunately, we do not know the exact value for the effect of different factors responsible for the overall treatment effect with both groups,” Sihvonen told COSMOS. But he dismissed the idea that the fluid introduced with the arthroscope could have improved the condition by flushing out the wound.

“That is, in our opinion, a poor explanation as there is previous evidence that it does not have an effect,” he said.

Sihvonen suggested that other factors at play could be the natural improvement of the disease – people just got better – or, in his view most likely, a psychological effect. Having gone through anaesthesia and apparent surgery they felt as if they had done something and should recover.

The study should make patients and their doctors think long and hard about the necessity for even minimal invasive surgery on degenerative knee disease and instead consider physiotherapy. Choong suggests, however, that the surgery may be of greatest value to patients with acute traumatic injuries – a group not included in the study. In these cases, a procedure to remove loose bodies and repair tears or blockages to the knee’s movement could be beneficial, he said.

Nevertheless, the study “highlights the need to improve the selection of patients if arthroscopic surgery is to be considered”, Choong says.

Latest Stories
MoreMore Articles