“Researchers at Baylor College of Medicine, for example, recently studied the outcome of arthroscopic knee surgery on patients with painful, worn-out knees who were given one of two types of arthroscopic surgery—either scraping out the knee joint or washing it out. Their results were then compared to patients who had unknowingly received a “pretend” surgery where doctors made tiny incisions in the knee as if to insert their surgical instruments, then did nothing.
Two years later, patients who underwent the pretend surgery reported equal improvement in pain relief and knee function as those patients who had received an actual surgery. The brain expected the imaginary surgery to improve the knee, and it did.”
amazing... that's the most extreme version of the power of the "placebo effect" I've heard or read... (the placebo effect is often misunderstood, as if it didn't teach us anything of importance...)