Article Citation

Stiell IG, Greenberg GH, McKnight RD, Nair RC, et al. Decision rules for the use of radiography in acute ankle injuries. Refinement and prospective validation. JAMA. 1993 Mar 3;269(9):1127-32. PMID 8433468

What we already know about the topic: Patients presenting with ankle injuries is a common occurrence in the emergency department, but less than 15% have a significant fracture. Despite a relatively low incidence, many patients receive xrays. In 1992, a group of physicians in Ottawa developed a clinical decision rule to aide the use of xray in ankle injuries using a number of clinical variables with 100% sensitivity for malleolar and midfoot fractures. However, the clinical decision rule needed to be prospectively validated and refined.

Why this study is important: This study was developed to validate and refine the previously defined clinical decision rules for radiographic imaging in ankle injuries.

Brief overview of the study: This study was performed prospectively and in two stages at emergency departments in two university hospitals. The first stage was a validation and refinement of the original rule and the second stage was a validation of the refined rule. The first stage used the original clinical decision rule for 1032 patients and was found to have sensitivities of 100% for detecting malleolar fractures and 98% for midfoot fractures. The rules were further refined and found that 2 variables (age 55 years or greater and cuboid tenderness) were unnecessary and that all clinically significant fractures could be identified without them. This new refined rule was validated in the second stage of the study and was found to have 100% sensitivity for malleolar and midfoot fractures. The study also demonstrated that application of the refined rule would have led to the relative reduction in xrays of 34% for ankle injuries and 30% for foot injuries. The refined rule is what we know today as the Ottawa ankle rules:

An ankle xray series is only necessary if there is pain near the malleoli and any of these findings:

-Bone tenderness at the posterior 6cm edge of the lateral or medial malleolus

-Inability to bear weight both immediately and in the emergency department (4 steps)

A foot xray series is only necessary if there is pain in the midfoot and any of these findings:

-Bone tenderness at the base of the 5th metatarsal

-Bone tenderness at the navicular

-Inability to bear weight both immediately and in the emergency department (4 steps)

Limitations: This rule should be used with caution in patients with multiple painful injuries, altered mental status, paraplegia or bone disease. While fairly uncommon, the Ottawa ankle rules do not assess for talus fractures and critics have argued that high velocity trauma and forced hyperextension injuries (mechanisms common in talus fractures) be exclusion criteria for the rules. While these rules have been validated, many physicians still do not use this rule. This barrier to use may be related to fear of litigation or patient expectations.

Take Home points: The Ottawa ankle rules are commonly used rule for ankle and midfoot injuries and have been validated by multiple followup studies with similar high sensitivities. These rules have also been validated in children older than 2 years of age. In addition, the Ottawa ankle rules have the potential to decrease xrays which could lead to savings of millions of dollars ($5 million in this study) and decrease patient wait times.

SOURCES:

Stiell IG, et al. A study to develop clinical decision rules for the use of radiography in acute ankle injuries. Ann Emerg Med. 1992 Apr;21(4):384-90.

Bachmann LM, Kolb E, Koller MT, Steurer J, ter Riet G. Accuracy of Ottawa ankle rules to exclude fractures of the ankle and mid-foot: systematic review. BMJ. 2003;326(7386):417.

Plint AC, et al. Validation of the Ottawa Ankle Rules in children with ankle injuries. Acad Emerg Med. 1999 Oct;6(10:1005-9.