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.
Practice Questions
A 32-year-old recreational soccer player presents to urgent care 2 hours after twisting his right ankle during a game. He reports pain along the lateral aspect of the ankle. On exam, there is mild swelling over the lateral malleolus and tenderness to palpation along the anterior edge of the lateral malleolus. There is no tenderness over the posterior edge or tip of either malleolus, no tenderness at the navicular bone, and no tenderness at the base of the fifth metatarsal. He was able to walk into the clinic and can take more than four steps in the exam room without significant difficulty, although it is uncomfortable. Applying the Ottawa Ankle Rules, which next step would the NP order?
Related Mnemonics
- RICE — Acute Soft-Tissue Injury Management
Sources
Ready to practice?
1,500+ AANP-style questions with rationales — free trial.