The Placebo effect is a curious phenomenon if I've ever looked upon one. Trials have shown people often react to a placebo in nearly the identical manner as an actual drug.
A placebo is an inert substance that has no effect on your body. Placebos such as sugar pills are often used in medical research as controls against the effects of experimental drugs.
The phenomenon however of patients believing to get an actual drug and still improve despite receiving no active substance at all, has become quite a strange phenomenon.
Even more strangely this phenomenon has been shown to work with surgical procedures. Sham surgeries have been shown to produce results that are equal to surgery, even though no actual surgery has been carried out.
In one such study (Mosely et al., 2002) comparing arthroscopic knee surgery with placebo sham surgery. Patients received either the real surgical treatment, or arthroscopic lavage only, or a simulated surgery. Keeping things blind as always neither the patient or the physicians who evaluated them for 24 months after the surgery knew which group they were in.
The results were measured subjectively by patient reports of pain and level of function of the afflicted knee. They also carried more objective tests of walking and stair climbing.
I guess the strangest result of this experiment was from the patient's reports. There were no reported differences between the 3 groups. Each group reported less pain and improved function of the knee. More significantly the sham surgery group, when measured objectively by the physicians, measured better at their given tasks like climbing stairs than the surgery groups.
The authors cautioned "The great potential for a placebo effect with surgery" and that "health care researchers should not underestimate the placebo effect, regardless of its mechanism"
Wow, I'd have to agree. It does beg's the question, why do the invasive surgery in the first place?
Mosely Et Al 2002 - https://www.ncbi.nlm.nih.gov/pubmed/12110735