Ottawa Knee Rule
Ottawa Knee Rule: knee x-ray indicated if any of age >= 55, isolated patellar tenderness, fibular-head tenderness, inability to flex to 90 degrees, or inability to bear weight 4 steps.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Age >= 55 years
- Yes
Result: At least one criterion present: knee x-ray indicated.
The tool opens with these values already filled in. Replace them with your own.
What the result means
- 0 criteria
- No criteria met: knee radiography is not required per source.
- >=1 criterion
- One or more criteria met: knee radiography is indicated per source.
What you enter
- Age >= 55 years
- Isolated patellar tenderness
- Fibular-head tenderness
- Cannot flex to 90 degrees
- Cannot bear weight 4 steps
How this is calculated
Stiell IG, et al. Ann Emerg Med. 1995;26(4):405-413 (Ottawa Knee Rule); 1997 validation. X-ray indicated if any of 5 criteria present. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.