Ottawa Ankle, Foot & Knee Rules

These are rule-out tools. Sensitivity for clinically significant fracture approaches 100% at modest specificity, so a negative rule is a safe reason not to x-ray — but a positive rule only means imaging is indicated, not that a fracture is there. Most positive patients have no fracture.

“Unable to bear weight” means four steps, both immediately after the injury and on assessment. Limping counts as bearing weight. A patient who walked in but cannot walk now does not meet it, and neither does one who could not walk at the scene but can now.

Age 55 belongs to the knee rule only. The 1992 ankle derivation included age and tenderness over the cuboid; the 1993 refinement dropped both, and the refined rule is the one validated and in use.

The ankle and foot rules are separate decisions from the same examination — malleolar pain drives the ankle series, midfoot pain the foot series, and a patient can need one, both or neither.

The rules were derived in adults. They are less well established in young children, in intoxicated or distracted patients, and where examination is unreliable — a head injury, or another painful injury drawing attention away.