How it's calculated
This is a decision rule, not an additive point score. An ankle X-ray is indicated only if there is pain in the malleolar zone AND at least one of: lateral malleolus tenderness, medial malleolus tenderness, or inability to bear weight. A foot X-ray follows the same logic for the midfoot zone.
Decision logic
| Series | Indicated if |
|---|---|
| Ankle X-ray | Malleolar zone pain AND (lateral malleolus tenderness OR medial malleolus tenderness OR unable to bear weight) |
| Foot X-ray | Midfoot zone pain AND (5th metatarsal base tenderness OR navicular tenderness OR unable to bear weight) |
Clinical use
- The Ottawa Ankle Rules are among the most extensively validated clinical decision rules in emergency medicine, with sensitivity approaching 100% for clinically significant fractures when applied correctly.
- "Unable to bear weight" specifically means unable to take 4 steps, both immediately after the injury and when assessed in the emergency department — not just reluctance to walk due to pain.
- The rules are validated for patients aged 18-55 without multiple painful injuries, significantly altered mental status, or reduced sensation in the leg — apply clinical judgement outside this population.
- Widespread adoption of these rules has substantially reduced unnecessary ankle/foot X-rays without an increase in missed fractures.
Frequently asked questions
What are the Ottawa Ankle Rules used for?
They help decide whether an X-ray is needed after an acute ankle or midfoot injury, substantially reducing unnecessary imaging while reliably identifying patients who do need it.
What does 'unable to bear weight' mean in this rule?
It specifically means inability to take 4 steps, assessed both immediately after the injury and again in the emergency department — not just general reluctance to walk because of pain.
Are the Ottawa Ankle Rules accurate?
Yes — they have near-100% sensitivity for clinically significant fractures in validation studies, meaning a negative result (no criteria met) very reliably excludes the need for an X-ray.
Do the Ottawa Ankle Rules apply to everyone?
They're validated for adults aged 18-55 without multiple painful injuries, significantly altered mental status, or reduced leg sensation — clinical judgement should be used outside this population.
References
- Stiell IG, et al. A study to develop clinical decision rules for the use of radiography in acute ankle injuries. Ann Emerg Med. 1992;21:384-390.
- Stiell IG, et al. Implementation of the Ottawa Ankle Rules. JAMA. 1994;271:827-832.
- Bachmann LM, et al. Accuracy of Ottawa ankle rules to exclude fractures of the ankle and mid-foot: systematic review. BMJ. 2003;326:417.