Ottawa
Ottawa Ankle & Foot Rules (Imaging Decision)
Decide X-ray vs. no X-ray in acute ankle/foot injury — 100% sensitive for clinically significant fracture.
For the FNP boards, ankle injuries test imaging stewardship — and the Ottawa Ankle Rules cut unnecessary X-rays roughly in half without missing fractures. X-ray the ankle if there is pain in the malleolar zone AND any of: bone tenderness at the posterior edge or tip of either malleolus, or inability to bear weight both immediately and in the office (four steps). X-ray the foot if there is midfoot pain AND tenderness at the navicular or fifth metatarsal base, or inability to bear weight. Sensitivity for clinically significant fracture approaches 100%. AANP exam questions use the rules to test when imaging is mandatory and when reassurance suffices.
- Ankle zoneMalleolar painPain anywhere in the malleolar zone PLUS one of the following triggers ankle X-ray.
- Ankle ATenderness at posterior edge or tip of LATERAL malleolus (distal 6 cm)Palpate the bone directly — soft-tissue tenderness doesn't count.
- Ankle BTenderness at posterior edge or tip of MEDIAL malleolus (distal 6 cm)Same rule — palpate the bone.
- Ankle CInability to bear weight both immediately and in clinic (4 steps)Limping counts as bearing weight; only true inability is positive.
- Foot zoneMidfoot painPain in midfoot zone PLUS one of the following triggers FOOT X-ray.
- Foot ATenderness at base of 5th metatarsalClassic Jones fracture location.
- Foot BTenderness at navicularPalpate on the medial midfoot.
- Foot CInability to bear weight both immediately and in clinic (4 steps)Same criterion as ankle.
Clinical Context
Validated decision rule for acute ankle/midfoot injury in patients ≥6 years old. Roughly 100% sensitive for clinically significant fracture and cuts unnecessary X-rays by ~30%. If all criteria are negative → no X-ray needed.
Does not apply to patients who are intoxicated, uncooperative, have distracting injuries, or present >10 days after injury. Separate rules exist for knee (Ottawa Knee Rules) and c-spine (NEXUS / Canadian C-spine).
AANP urgent-care stem: twisted ankle 2 hours ago, walked into clinic, tender only over anterior talofibular ligament, no bone tenderness → no X-ray needed. Trap: "couldn't bear weight at the time but walks in now" — that still counts as positive and triggers imaging.
Related Mnemonics
- RICE — Acute Soft-Tissue Injury Management
Sources
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