Ottawa Ankle Rule in the Evaluation for Fractures in Blunt Ankle Injuries

Summary:

The Ottawa Ankle Rule can be used in the evaluation of ankle injuries to identify patients who have a low likelihood of fracture. This obviates the need for obtaining ankle radiographs in certain patients, reducing cost, resource utilization, radiation exposure, and potentially, emergency department length of stay.

Interpretation:

A patient presenting with ankle injury needs ankle radiographs only if there is pain near the malleoli and any of the following findings are true:

Inability to bear weight both immediately and in the emergency department (four steps)
Bone tenderness at the posterior edge or tip of either malleolus

A patient presenting with ankle injury needs foot radiographs only if there is pain in the midfoot and any of the following findings are true:

Inability to bear weight both immediately and in the emergency department (four steps)
Bone tenderness at the navicular or the base of the fifth metatarsal

Additional Clinical Considerations:

The Ottawa ankle rule is an excellent screening tool for patients with ankle injuries. It has very high sensitivity (100% in initial studies and 97.6% in subsequent meta-analysis), and is therefore unlikely to miss clinically significant ankle and midfoot injuries. It has been studied in both adult and pediatric patients.

The Ottawa ankle rule is well validated and has been shown to limit the number of radiographs obtained for ankle injuries. However, there is some reluctance to use it due to ease and speed of obtaining radiographs, patient expectations, and clinician fears over missed fractures and possible litigation.

Author: Dylan Kellogg, MD
Editors: Anthony J. Busti, MD, PharmD, FNLA, FAHA
Last Updated: August 2015

Landmark or Original Studies

Stiell IG, Greenberg GH, McKnight RD, Nair RC, McDowell I, Worthington JR. A study to develop clinical decision rules for the use of radiography in acute ankle injuries. Ann Emerg Med. 1992 April;21:384-90. PubMed

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Level of Evidence	1b
Study Design	Prospective, Derivation Study
Sample Size	n = 155 in pilot study n = 750 in the main study
Population	Adult patients with blunt ankle injuries presenting to two Canadian tertiary care hospital emergency departments
Inclusion Criteria	All adult patients presenting with acute blunt ankle injury
Exclusion Criteria	Age less than 18, pregnancy, isolated skin injuries, injury more than 10 days earlier, return visit for same ankle injury
Interventions	Thirty-two standardized clinical variables were assess and recorded before radiography. All patients received radiographs.
Primary Endpoint	Develop decision rules that will predict fractures in patients with ankle injuries, thereby assisting clinicians in being more selective in their use of radiography.
Results	70 significant malleolar fractures were identified in 689 ankle radiographic series. All were among people who had pain near the malleoli, age 55 or greater, localized bony tenderness along the posterior edge or tip of either malleolus, or inability to bear weight (for at least 4 steps) both immediately after the injury and in the ED. 32 significant midfoot fractures were identified on 230 foot radiographic series. All were found among patients with pain in the midfoot and bony tenderness at the base of the fifth metatarsal, the cuboid, or the navicular.
Conclusions	Use of these decision rules was 100% sensitive for both ankle and foot fractures. The ankle criteria for 40.1% specific and could have potentially decreased radiographic utilization by 36%, while the foot criteria for 24.7% specific and could have decreased radiographic utilization by 21.3%.
Location	Two tertiary care hospitals in Ottawa, Canada
Funding	Not reported
Comments	Authors define clinically insignificant fractures as avulsion of 3mm or less because these fractures are typically not treated with plaster immobilization.

Stiell IG, Greenberg GH, McKnight RD, Nair RC, McDowell I, Reardon M, Stewart JP, Maloney J. Decision rules for the use of radiography in acute ankle injuries: refinement and prospective validation. JAMA. 1993 Mar 3;269(9):1127-32. PubMed

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Study Design	Two prospective stages: 1) Validation and refinement of original rules; 2) Validation of refined rules
Sample Size	n = 1032 in the first stage n = 453 in the second stage
Population	Adult patients with blunt ankle injuries presenting to two Canadian tertiary care hospital emergency departments. The two stages were conducted on different groups of patients.
Inclusion Criteria	All adult patients presenting with acute blunt ankle injury who presented when one of 21 designated emergency physicians were on duty.
Exclusion Criteria	Age less than 18, pregnancy, isolated skin injuries, referral from outside hospital with radiographs, injury more than 10 days earlier, return visit for same ankle injury.
Interventions	15 variables assessed in stage 1, 6 in stage 2, prior to radiography. All patients received radiographs subsequently. When possible a second emergency physician blinded to the first evaluation repeated it.
Primary Endpoint	Validate and refine previously derived clinical decision rules that aid in the efficient use of radiography in acute ankle injuries.
Results	Stage 1 - Ankle: 121 malleolar zone fractures identified. Initial rule 100% sensitive for malleolar zone fractures. Reevaluation of variables resulted in the following criteria: bone tenderness at the posterior edge or tip of the lateral malleolus, bone tenderness at the posterior edge or tip of the medial malleolus, inability to bear weight both immediately and in the emergency department. This revised rule had 100% sensitivity and a specificity of 41% vs 39% with initial rule. Stage 1 - Foot: 49 midfoot zone fractures identified. Initial rule 98% sensitive for midfoot fractures. Reevaluation of variables resulted in the following criteria: bone tenderness at base of fifth metatarsal, bone tenderness at navicular, inability to bear weight immediately and in the emergency department. Sensitivity of 100%, specificity of 79% vs 70%. Stage 2 - Ankle: 50 ankle fractures, 100% sensitive Stage 2 - Foot: 19 foot fractures, 100% sensitive
Conclusions	Rules were 100% sensitive and their use would have reduced ankle radiographs for 34% and foot radiographs by 30%.
Funding	Not Reported
Comments	Authors define clinically insignificant fractures as avulsion of 3mm or less because these fractures are typically not treated with plaster immobilization.

Supporting Studies

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 Feb 22;326(7386):417. PubMed

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Plint AC, Bulloch B, Osmond MH, Stiell I, Dunlap H, Reed M, Tenenbein M, Klassen TP. Validation of the Ottawa ankle rules in children with ankle injuries. Acad Emerg Med. 1999 Oct;6(10):1005-9. PubMed

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Study Design	Prospective Validation Study
Sample Size	n = 670
Population	Patients age 2-16 presenting to two Canadian pediatric emergency departments
Inclusion Criteria	All patients 2-16 with ankle injuries
Exclusion Criteria	Presence of multiple injuries, obvious open fractures, evidence of neurovascular compromise, underlying disease predisposing to fractures, underlying disease with sensory abnormalities, isolated skin injury, return visit for same injury, referred to ED with x-rays, clinically intoxicated.
Interventions	Application of Ottawa ankle rule criteria. Not all patients received x-rays. The 27 patients who did not, received telephone follow-up at 5-7 days to determine their outcomes.
Primary Endpoint	Validation of Ottawa ankle rule in pediatric patients
Results	86 patients with significant fractures, 119 with Salter-Harris type 1. Ottawa ankle rule 100% sensitive for clinically significant fractures of ankle and midfoot, as well as for Salter-Harris type 1 fractures. Only 91% sensitive for clinically insignificant fracture of ankle and 82% for clinically insignificant midfoot fractures. Application for the rule would have reduced ankle x-rays by 16% and foot x-rays by 29%.
Conclusions	The Ottawa ankle rule is sensitive for detecting clinically significant ankle and midfoot fractures in children.
Location	Two Canadian pediatric emergency departments at tertiary care hospitals
Funding	Children's hospital of Eastern Ontario Research Institution Grant
Comments	Authors define clinically insignificant fractures as avulsion of 3mm or less because these fractures are typically not treated with plaster immobilization. 305 patients who met eligibility criteria were excluded due to physician noncompliance with completing appropriate paperwork. This group had a lower incidence of fractures than the included patients.

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MESH Terms or Keywords
Ottawa Ankle Rule, Ankle Injuries Ottawa, Ankle Xrays Ottawa Rule

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