What are the Ottawa Ankle Rules?

The Ottawa Ankle Rules are validated clinical criteria developed in 1992 to identify patients who need ankle or foot X-rays after acute injury. They have near 100% sensitivity for fractures and reduce unnecessary imaging by 30–40%.

Who should NOT be assessed with this tool?

The rules apply to adults (≥18 years) with acute ankle or midfoot pain after injury. Exclude: patients who cannot bear weight due to another injury, pregnant patients, patients with diminished sensation, or those presenting more than 10 days after injury.

What does "bear weight" mean in this context?

The patient must be able to take four steps (weight-bearing steps), regardless of limping. If they take four steps, they can bear weight even if painful.

Where is the posterior edge of the fibula / medial malleolus?

The posterior 6 cm of the distal fibula (lateral malleolus) or tibia (medial malleolus). Tenderness anywhere in this zone, not just the tip of the malleolus, is a positive finding.

What is the base of the fifth metatarsal?

The bony prominence felt on the outer edge of the midfoot, roughly at the level of the little-toe metatarsal base. Tenderness here suggests a fifth metatarsal avulsion fracture.

How accurate are the Ottawa Ankle Rules?

Multiple prospective studies show sensitivity of 96–100% for detecting clinically significant fractures, with specificity around 30–40%. A negative result (no X-ray needed) is highly reliable; a positive result warrants imaging.

Ottawa Ankle Rule

Name: Ottawa Ankle Rule
Availability: InStock
Author: Nham Vu

Apply the Ottawa Ankle Rules to determine whether ankle or foot X-rays are clinically indicated after an acute injury.

Assess which zone?

Ankle only Midfoot only Both zones

Ankle Series — X-ray indicated if ANY are present

Bone tenderness on palpation OR inability to bear weight

Tenderness over posterior edge or tip of lateral malleolus (distal 6 cm of fibula)

Tenderness over posterior edge or tip of medial malleolus (distal 6 cm of tibia)

Unable to bear weight both immediately after injury AND in the emergency department (4 steps)

Assessment Result

Select a zone and check findings to see the recommendation.

Clinical note: The Ottawa Ankle Rules apply to adults (≥18 years) with acute ankle or midfoot pain after trauma, presenting within 10 days of injury. Not validated in children, pregnant patients, or those with impaired sensation. Clinical judgment always takes precedence.

Anatomy Quick Reference

Lateral malleolus: Posterior 6 cm of distal fibula (outer ankle bump)

Medial malleolus: Posterior 6 cm of distal tibia (inner ankle bump)

5th metatarsal: Base of little-toe bone — outer midfoot prominence

Navicular: Medial midfoot — medial prominence between malleolus and arch

Bear weight: 4 full steps, regardless of limping

Summary