Medicine rests on an uneven evidence base. Some interventions are supported by large multicentre randomised controlled trials that have a low risk of bias and are powered for hard endpoints—a high level of evidence. Others depend on retrospective observational data that provide a lower level of evidence. Yet others were theorised and consid- ered biologically or mechanistically plausible and are heirlooms of “eminence based medicine.”

Some interventions are just plain wrong and have real costs and harms, without countervailing benefits. Medical reversals may occur when well done clinical trials, systematic reviews, and meta-analyses of trials find current practice to be no better than a lesser treatment or placebo. Classic examples of reversals are anti-arrhythmic drugs for patients with recent myocardial infarction and hormone replacement therapy for menopausal women.1

The evidence base for orthopaedics compares unfavourably with other fields of medicine. Only 20% of procedures are estimated to be supported by at least one low-risk-of-bias randomised controlled trial showing that surgery is superior to a non-operative alternative.2

A similar review …