What Is the Ottawa Ankle Rule? A Clinician's Quick Reference
The Ottawa Ankle Rule is one of the most elegant decision tools in medicine: three criteria, 99%+ sensitivity, and the ability to cut unnecessary ankle x-rays by 30–40%. If you're heading into clinical rotations or board prep, this one belongs in permanent memory.
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Updated July 2026
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The 60-second version
Apply to patients ≥18 with ankle injury within 10 days
Tenderness: posterior edge/tip of lateral OR medial malleolus (distal 6 cm each)
Or: inability to weight-bear 4 steps immediately AND in the ED
~99.3% sensitivity for clinically significant fractures
NOT valid in children <18, pregnancy, intoxication, or distracting injuries
X-ray the ankle ONLY if there is pain in the malleolar zone AND any of: (1) bone tenderness at the posterior edge or tip of the lateral malleolus (distal 6 cm), (2) bone tenderness at the posterior edge or tip of the medial malleolus (distal 6 cm), or (3) inability to weight-bear both immediately after injury AND in the ED (4 steps).
For the Foot (Ottawa Foot Rule)
X-ray the foot if there is pain in the midfoot zone AND any of: (1) bone tenderness at the base of the 5th metatarsal, (2) bone tenderness at the navicular, or (3) inability to weight-bear as described above. These are commonly tested together — know which landmarks apply to ankle vs. foot.
Sensitivity and Specificity
The Ottawa Ankle Rules have a sensitivity of ~99.3% for clinically significant fractures (meta-analyses across >15,000 patients). Specificity is lower (~30–40%), meaning false positives are common — the rules are designed to catch all fractures, not to eliminate all imaging. They reduce unnecessary x-rays by approximately 30–40%.
Clinical Pearls and Pitfalls
The rule is NOT valid in: children under 18 (separate pediatric criteria), pregnant patients, intoxicated patients, those with diminished sensation, isolated skin injuries, or multiple injuries distracting from the ankle assessment. Always reassess if the patient's pain changes. On boards, the question often tests whether you know the rule's limitations, not just its criteria.
Test yourself
Quick check — 3 questions
1. A 24-year-old rolls their ankle playing basketball. They hopped off the court and walked briefly before stopping. In the ED, they have tenderness over the posterior tip of the lateral malleolus but no medial tenderness and can take 4 steps. Ottawa Ankle Rule?
Explanation. Posterior tip of the lateral malleolus tenderness is a positive Ottawa criterion regardless of weight-bearing status. X-ray is indicated.
2. Which of the following patients is the Ottawa Ankle Rule NOT validated for?
Explanation. The Ottawa Ankle Rule is NOT validated in patients under 18. Children have open physes and require different clinical assessment.
3. What approximate reduction in x-rays does correct Ottawa Rule application provide?
Explanation. Proper application of the Ottawa Ankle Rules reduces unnecessary ankle radiographs by approximately 30–40% without missing clinically significant fractures.
Frequently asked questions
What is the sensitivity of the Ottawa Ankle Rule?
The Ottawa Ankle Rule has approximately 99.3% sensitivity for clinically significant ankle fractures across multiple large meta-analyses. Its specificity is lower (~30–40%), but it's designed as a screening tool — the priority is not missing fractures, not eliminating all imaging.
Does the Ottawa Ankle Rule apply to children?
No. The original Ottawa Ankle Rule was validated in adults (≥18 years). Children have open growth plates (physes) that can be injured without clear plain film findings, making the adult decision rule unreliable. Separate tools (like the Low Risk Ankle Rule) exist for pediatric patients.
What is the difference between the Ottawa Ankle Rule and the Ottawa Foot Rule?
They're often called together as the 'Ottawa Rules.' The Ankle Rule assesses the malleolar zone and uses malleolar tenderness landmarks. The Foot Rule assesses the midfoot zone using the base of the 5th metatarsal and navicular. Weight-bearing inability is shared criterion for both.
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