Ottawa ankle rules reduce the rate of referral for ankle radiography [Classics Series]

1. The Ottawa ankle rules significantly reduced referral for ankle, but not foot, radiography in the emergency department.

2. Patients without fractures spent less time in the emergency department if not referred for radiography without an increased rate of missed fractures.

Original Date of Publication: September 1995

This study summary is an excerpt from the book 2 Minute Medicine’s The Classics in Medicine: Summaries of the Landmark Trials, 2e (The Classics Series).

Study Rundown: Ankle and foot injuries are some of the most common complaints evaluated in the emergency department. While relatively few patients sustain a fracture related to their injury, it has long been standard practice to perform plain radiography of the ankle and/or foot on virtually all patients. This, along with unreliable findings made through history taking and physical examination defined the need for decision rules on the use of radiography for acute ankle injuries. The Ottawa ankle rules (Table I) were designed to allow physicians to rapidly identify patients with a negligible risk of fracture based on the assessment of weight-bearing ability and areas of bone tenderness. These decision rules have subsequently been validated and are highly sensitive in identifying fractures.

In the large multicenter trial conducted by Stiell and colleagues, rates of referral for ankle and foot injuries were compared before and after the introduction of the Ottawa ankle rules. The results of this study showed that implementation of the Ottawa ankle rules significantly reduced referral for ankle radiography. Patients without fractures also spent less time in the emergency department if they were not referred for radiography without an increased rate of missed fractures.

Please click to read study in BMJ

In-Depth [non-randomized controlled trial]: This study was conducted across 8 emergency departments in Canada. All adult patients seen at a participating study site with an ankle injury during the 12 month control (before) or intervention (after) periods were included. Before the start of the intervention period, the Ottawa ankle rules were introduced by means of a 1 hour lecture and supported by handouts, pocket cards and posters in each emergency department. The decision to order radiography was left to the discretion of the treating physician. Treating physicians included emergency and family physicians as well as housestaff. Referral for radiography was determined through radiology reports. As part of the intervention, patients deemed to be without fracture were followed up by telephone after 10 days if they did not receive any radiography. Patients that were seen during the first 7 days of each month and received radiography were also followed up.

A total of 12 777 eligible patients (median age 32, range 18-101; 53% men) were seen in a participating emergency department for treatment of an ankle injury. Patients evaluated during the pre-intervention (n = 6288) and intervention (n = 6489) periods did not significantly differ with respect to any baseline patient characteristics. During the pre-intervention period, 82.8% of patients were referred for ankle radiography compared to 60.9% during the intervention period (p < 0.001), corresponding to a relative reduction of 26.4%. For 4.9% of cases, radiography was unnecessarily performed according to the Ottawa ankle rules, where only 0.5% of these cases were the result of patient insistence. The proportion of patients referred for ankle imaging was significantly less at all 8 participating hospitals and across all physician subgroups. For foot imaging, however, significant reductions in referral were noted at only 3 of the 8 study sites. Among patients without fracture, those that were not referred for radiography spent less time in the emergency department compared to patients that underwent imaging studies (p < 0.001). Of the 2033 patients comprising the follow up group, 10 (0.5%) had a fracture diagnosed after discharge despite no repeat injury, 7 of which had not received radiography (n = 1301). It should be noted, however, that the Ottawa ankle rules were correctly applied in only 1 of the 7 patients from the latter follow-up group. A cost minimization analysis also showed that the mean total expense for patients who had no radiography was less than those who had radiography (p < 0.001).

Table I. Ottawa ankle rules.

Stiell I, Wells G, Laupacis A, Brison R, Verbeek R, Vandemheen K, et al. Multicentre trial to introduce the Ottawa ankle rules for use of radiography in acute ankle injuries. BMJ. 1995 Sep;311(7005):594-7.

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