Ottawa Ankle · Ottawa Ankle Rules

A rule-out, not a rule-in. Four bony points plus the ability to weight-bear, applied to an acute ankle or midfoot injury to decide whether an x-ray is needed at all.

Ankle series if there is pain in the malleolar zone and bony tenderness at the posterior edge or tip of either malleolus, or an inability to weight-bear four steps immediately and in the department.
Foot series if there is pain in the midfoot zone and bony tenderness at the base of the 5th metatarsal or the navicular, or the same weight-bearing failure.

Every acute ankle or midfoot injury, at the first contact. It takes under a minute and it is the difference between a student who sends a patient for an x-ray "to be safe" and one who can say why.

On placement you are usually applying it retrospectively — the patient already has or hasn't had a film. Use it anyway: it tells you whether the absence of imaging is reasonable, which is the more common situation in outpatients.

Not scored. Any one criterion positive → image. All negative → the rule says imaging is not indicated.

Palpate the posterior edge of the malleolus, not the tip alone — that is the part students skip, and it is where the rule's sensitivity comes from.

Anything about ligament injury. A negative Ottawa rule does not tell you the ankle is fine — it tells you a fracture is unlikely. The sprain grading, the syndesmosis and the talar dome are separate questions.

Pair it with: FAAM for function, CAIT if instability is the complaint, and a re-examination at 4–6 days when swelling has settled — the point at which an occult fracture or an osteochondral lesion becomes palpable.

Built to be highly sensitive and deliberately not specific. A negative rule is designed to make a clinically significant fracture very unlikely; a positive rule tells you almost nothing about whether a fracture is actually present.

No verified sensitivity or specificity figure is carried in our library, and none is printed here. Read the derivation study (Stiell et al. 1992) for the numbers.

Where it does not apply: under 18, intoxicated, distracting injury, gross swelling preventing palpation, sensory deficit, or presentation more than about 10 days after the injury. Outside those bounds the rule is not the rule.