Trauma & Burns

Ottawa Ankle and Foot Rules Calculator

Decides whether an acute ankle or midfoot injury needs an ankle or foot X-ray series.

Reviewed by Alex G, BSN, RN, CEN, CCRN, CMC, NREMT-P · From the Reference tab of the app

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Formula

Ankle series if malleolar-zone pain and any of: tenderness along the distal 6 cm of the posterior edge of the fibula or tip of the lateral malleolus; tenderness along the distal 6 cm of the posterior edge or tip of the medial malleolus; unable to bear weight for 4 steps both immediately and in the emergency department
Foot series if midfoot-zone pain and any of: tenderness at the base of the fifth metatarsal; tenderness at the navicular; unable to bear weight for 4 steps both immediately and in the emergency department

How it is used

• The refined rules were 100% sensitive for malleolar and midfoot fractures and would cut ankle series by 34% and foot series by 30% (Stiell 1993).
• Across 27 studies and 15,581 patients, pooled sensitivity was 97.6% and fracture risk after a negative rule under 2% (Bachmann 2003).
• Do not apply under 18, with intoxication, multiple painful injuries, head injury, pregnancy or reduced sensation from a neurological deficit (NHS Scotland CEM).

Key points

• A negative rule rules out a fracture, not a ligament injury, and does not apply to the excluded groups: use judgment there.

Same formula as the app. Open it in the web app.

Related one-pagers

• Burns
• Trauma: Primary and Secondary Survey

Related calculators

• Burn Fluids (ABA Consensus 2 mL/kg)
• Burn Size (Rule of Nines)
• Canadian CT Head Rule (CCHR)
• NEXUS Cervical Spine Criteria (NEXUS)
• Ottawa Knee Rule

For education and exam preparation only. Follow your institution’s protocols. For education and exam preparation only. Verify results independently and follow your institution’s protocols. Not a substitute for clinical judgment.