Emergency Medicine

Ottawa Knee Rule for Acute Knee Injury Radiography

Evaluates 5 clinical criteria to determine if knee X-rays are indicated after acute knee trauma (100% sensitivity).

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Parameters

Ottawa Knee Rule for Acute Knee Injury Radiography Result

Formula

Ottawa Knee Rule: Positive if ANY of the 5 criteria are met:
1. Age ≥ 55 | 2. Isolated patella tenderness | 3. Fibular head tenderness | 4. Inability to flex to 90° | 5. Inability to bear weight for 4 steps.

Clinical Pearls

One of the most robust clinical decision instruments in emergency medicine, reducing radiation exposure, emergency department throughput times, and healthcare costs.

Limitations

Not applicable in children < 18 years, patients with altered mental status, multiple painful distracting injuries, paraplegia, or pregnancy.