Invasiveness may explain its potency

Friday, August 11th, 2017

You can call it one hell of a placebo:

The guy’s desperate. The pain in his knee has made it impossible to play basketball or walk down stairs. In search of a cure, he makes a journey to a healing place, where he’ll undergo a fasting rite, don ceremonial garb, ingest mind-altering substances and be anointed with liquids before a masked healer takes him through a physical ritual intended to vanquish his pain.

Seen through different eyes, the process of modern surgery may look more more spiritual than scientific, said orthopedic surgeon Stuart Green, a professor at the University of California, Irvine. Our hypothetical patient is undergoing arthroscopic knee surgery, and the rituals he’ll participate in — fasting, wearing a hospital gown, undergoing anesthesia, having his surgical site prepared with an iodine solution, and giving himself over to a masked surgeon — foster an expectation that the procedure will provide relief, Green said.

These expectations matter, and we know they matter because of a bizarre research technique called sham surgery. In these fake operations, patients are led to believe that they are having a real surgical procedure — they’re taken through all the regular pre- and post- surgical rituals, from fasting to anesthesia to incisions made in their skin to look like the genuine operation occurred — but the doctor does not actually perform the surgery. If the patient is awake during the “procedure,” the doctor mimics the sounds and sensations of the true surgery, and the patient may be shown a video of someone else’s procedure as if it were his own.

Sham surgeries may sound unethical, but they’re done with participants’ consent and in pursuit of an important question: Does the surgical procedure under consideration really work? In a surprising number of cases, the answer is no.

A 2014 review of 53 trials that compared elective surgical procedures to placebos found that sham surgeries provided some benefit in 74 percent of the trials and worked as well as the real deal in about half.1 Consider the middle-aged guy going in for surgery to treat his knee pain. Arthroscopic knee surgery has been a common orthopedic procedure in the United States, with about 692,000 of them performed in 2010,2 but the procedure has proven no better than a sham when done to address degenerative wear and tear, particularly on the meniscus.3

Meniscus repair is only one commonly performed orthopedic surgery that has failed to produce better results than a sham surgery. A back operation called vertebroplasty (done to treat compression fractures in the spine) and something called intradiscal electrothermal therapy, a “minimally invasive” treatment for herniated disks and low back pain, have also produced study results that suggest they may be no more effective than a sham at reducing pain in the long term.

Such findings show that these procedures don’t work as promised, but they also indicate that there’s something powerful about believing that you’re having surgery and that it will fix what ails you. Green hypothesizes that a surgery’s placebo effect is proportional to the elaborateness of the rituals surrounding it, the surgeon’s expressed confidence and enthusiasm for the procedure, and a patient’s belief that it will help.

Weirdly enough, surgery’s invasiveness may explain some of its potency. Studies have shown that invasive procedures produce a stronger placebo effect than non-invasive ones, said researcher Jonas Bloch Thorlund of the University of Southern Denmark. A pill can provoke a placebo effect, but an injection produces an even stronger one. Cutting into someone appears to be more powerful still.

Comments

  1. Jim says:

    I have post-polio syndrome and fall frequently. I have twice had knee operations to repair damage from falls. In both cases the resulting improvement in walking was excellent. After one fall I could hardly walk due to the damage done by the fall. After repairing damaged cartilage I returned to normal function.

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