The Ottawa ankle rules can reduce unnecessary radiographs in patients with ankle injury; two controlled before and after trials showed benefit—they reduced radiographs by 26% and 28%, with no adverse consequences.1 The rules have been described as “a safe, cost effective, and reliable approach to assessing injured ankles with impressive consistency.”2 Given this, surely all staff in all emergency departments should be using these rules. This is not the case, however—surveys have shown variable uptake. Furthermore, even when the rules are promoted within a service with a carefully developed implementation plan, as described by Bessen and colleagues in the linked quality improvement report (doi:10.1136/bmj.b3056), the effect seems modest.3 Why should this be?

Recognition of the problems of implementation is not new—it is hard enough for drugs with proved efficacy, yet alone complex interventions such as the Ottawa ankle rules. Although we need evidence to tell us which interventions work and should be widely implemented, we also need evidence on what can effectively enable wide implementation.4 This is the focus …