The "placebo" response in osteoarthritis and its implications for clinical practice.

Many observations support a major biological effect from the way in which people interpret the meaning of each component of their medical experience and the context in which this occurs. A recent systematic review of randomised controlled trials in osteoarthritis has demonstrated that the effect size of "placebo" is substantial and is usually greater than that obtained from the specific effect of an individual treatment. In the context of a randomised controlled trial, such a large placebo or "meaning" response is considered a nuisance, but in the context of clinical practice the optimisation of such meaning and contextual responses, through enhanced "care", could greatly benefit people who suffer from osteoarthritis.