Ottawa ankle rules Calculator: Free emergencymedicine Risk Score & Interpretation

How it Works

Assessment Criteria

01

1. Evaluate for Bone Tenderness: Palpate the posterior edge or tip of the lateral malleolus (distal 6 cm).

02

2. Evaluate for Bone Tenderness: Palpate the posterior edge or tip of the medial malleolus (distal 6 cm).

03

3. Evaluate for Bone Tenderness: Palpate the base of the fifth metatarsal.

04

4. Evaluate for Bone Tenderness: Palpate the navicular bone.

05

5. Assess Weight Bearing: Can the patient bear weight both immediately after the injury and in the ED for 4 steps (limping is acceptable)?

Interpretation Thresholds

Rule Positive	Pain in the malleolar or midfoot zone AND any one of the following: bone tenderness at lateral/medial malleolus, base of 5th metatarsal, or navicular, OR inability to bear weight for 4 steps. Radiography indicated.
Rule Negative	No bony tenderness in the specified zones AND able to bear weight. Radiography is NOT required.

Clinical Pearls

Clinical Pearl

The Ottawa Ankle Rules have a sensitivity approaching 100% for ruling out significant fractures. Note that palpation must specifically involve the posterior edge or tip of the malleoli—not the anterior aspect or the ligamentous structures.

Known Limitations

Will not identify avulsion fractures <3mm, though these are typically managed non-operatively like severe sprains.

False positives can be high if the examiner applies pressure to soft tissues (ligaments) rather than strictly the bone.

Not intended for patients with chronic instability or subacute presentations (>10 days post-injury).

Next Steps

Actionable Clinical Management

01

1. If Rule Negative: Clinically diagnose an ankle/midfoot sprain. Discharge with rest, ice, compression, elevation (RICE), and analgesia. Arrange follow-up if symptoms do not improve in 5-7 days.

02

2. If Ankle Zone Positive: Order standard three-view ankle radiographs (AP, lateral, and mortise).

03

3. If Midfoot Zone Positive: Order foot radiographs (AP, lateral, and oblique views).

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4. If both zones positive: Order both ankle and foot radiographic series.

The Evidence

Derivation Study

Decision rules for the use of radiography in acute ankle injuries. Refinement and prospective validation.

Stiell IG et al. • JAMA.. 1993;Vol 269(9): 1127-1132. The foundational study that derived and validated the criteria, leading to widespread international adoption.

Origins & History

Development Context

Developed by Dr. Ian Stiell and colleagues at the Ottawa Hospital in the early 1990s. The goal was to establish a highly sensitive clinical decision rule to safely curb the routine (and often unnecessary) use of x-rays for every twisted ankle presenting to the ED.

Ottawa Ankle Rules

When to Use

When to Use

Patient Population

How it Works

Assessment Criteria

Interpretation Thresholds

Clinical Pearls

Clinical Pearl

Known Limitations

Next Steps

Actionable Clinical Management

The Evidence

Derivation Study

Decision rules for the use of radiography in acute ankle injuries. Refinement and prospective validation.

Origins & History

Development Context

Related Tools

In Recent Clinical News

Ottawa Ankle Rules

When to Use

When to Use

Patient Population

How it Works

Assessment Criteria

Interpretation Thresholds

Clinical Pearls

Clinical Pearl

Known Limitations

Next Steps

Actionable Clinical Management

The Evidence

Derivation Study

Decision rules for the use of radiography in acute ankle injuries. Refinement and prospective validation.

Origins & History

Development Context

Related Tools

In Recent Clinical News