MSKOrthopaedics

Ottawa Knee Rules for X-Ray Decision

Decision rule for knee X-ray after acute injury. >98% sensitivity for clinically important fractures. Validated to safely reduce imaging by 25–50%.

Age ≥ 55 years?

Tenderness at head of fibula?

Isolated tenderness of the patella (no other bony tenderness)?

Inability to flex knee to 90°?

Unable to bear weight (4+ steps) immediately and in ED?

Negative

Ottawa Knee Rules Result

Ottawa Negative — Knee X-ray not required

No positive criteria identified. Knee X-ray is not required. Safe to manage clinically. Note: Apply only to acute knee injuries in adults. Exclude patients with isolated skin injuries, intoxication, pregnancy, distracting injury, or altered consciousness.

Reference: Stiell IG et al. Ann Emerg Med 1996

Medical Disclaimer: This calculator is a clinical decision support tool for qualified healthcare professionals. It does not replace clinical judgement. Always interpret results in the full clinical context. Reference: Stiell IG et al. Ann Emerg Med 1996.

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