Knee Surgery – Placebo?

New England Journal of Medicine - Colin Badali   PubMed - Colin Badali   Cochrane - Colin Badali

Perhaps one of the most astounding examples of the placebo effect was demonstrated in a relatively famous study – “Moseley JB, O’Malley K, Petersen NJ.  A controlled trial of arthroscopic surgery for osteoarthritis of the knee. N Engl J Med. 2002″.  In this remarkable study, patients with osteoarthritis in the knee improved the same amount regardless of whether they received fake surgery, or real surgery.  “In this controlled trial involving patients with osteoarthritis in the knee, the outcomes after arthroscopic lavage or arthroscopic debridement were no better than those after a placebo procedure”.  Not only was this study published in a prestigious journal, but the results have been fully supported by a Cochrane Collaboration review (a gold standard in research review – if you’re ever seeking to fact-check a particular treatment/modality, just Google it, for ex. “cochrane review ultrasound for low-back pain” or “cochrane review acupuncture for depression”.  This might be a better way to find out about the legitimacy of a modality, rather than peruse through hundreds of studies on PubMed, which are of varying quality and relevance.

The placebo effect is an incredibly important concept in medicine.  It may be hard to believe, but it involves real and proven neurobiological mechanisms of action, when it comes to pain relief, immunosuppression, Parkinson’s disease and depression.  Brain imaging techniques have shown that placebo can have a measurable effect on physiological changes in the brain.  Changes like heart rate, blood pressure, chemical activity in the brain – in cases involving pain, depression, anxiety, fatigue, and certain Parkinson’s symptoms.

The placebo effect is part of the response to any active medical intervention or therapy.

The placebo effect indicates the enormous importance of perception and the brain’s role in physical health.  The use of placebos, however, is very controversial in medicine, as it involves the issue of practitioner-patient deception.  The placebo response may be partly due to an alteration of hormones, endocannabinoids, endogenous opioids, expectancy effects, amongst other factors.

The placebo relates very much to a patient’s expectations.  Much like the “nocebo” effect, which can lead to negative effects if a patients expects a harmful outcome, the placebo can lead to positive results if the patients expects them.

In other words, placebo effects, it is hypothesized, are produced by the self-fulfilling effects of response expectancies, in which thinking that one will feel different will lead to a patient feeling different.  According to this theory, the belief that one has received treatment can produce the effects of a real treatment.  Placebo can mimic classical conditioning, in which a placebo and an actual stimulus are used at the same time, until the placebo is associated with the effect of the actual stimulus.  Both conditioning and expectations play a role in the placebo effect – clients who think a treatment will work display a stronger placebo effect than those that don’t, as seen in certain acupuncture studies.  The mechanism behind many other therapies could be similar.

Of interest: Studies have been done demonstrating that people given sham ergogenic aids (fake sport-enhancing drugs), display improved endurance, speed, and strength.

Colin Badali, RMT, CSCS