Emergency Medicine

Ottawa Knee Rule

Whether a knee X-ray is needed after injury.

Education and reference only. Not a substitute for clinical judgement, local policy or product labelling. Always verify before clinical use. Values are calculated in your browser and never stored.

When to use

Use after acute knee injury to decide whether an X-ray is needed. If NO criteria are present, a clinically significant fracture is very unlikely.

Why use

It safely reduces unnecessary knee radiographs.

Evidence & references

  1. Stiell IG et al. Prospective validation of a decision rule for the use of radiography in acute knee injuries. JAMA. 1996.

About the creator

Stiell IG et al.

Related calculators

Ottawa Ankle RulesWhether ankle/foot X-rays are needed after injury.NEXUS C-Spine CriteriaWhether cervical-spine imaging can be avoided.

Need a calculator we don't have — or a custom tool?

We build evidence-led clinical calculators, dashboards and reference tools for teams.

Request a Custom Tool ☎ +44 7448 439750
☎ Call Get a Proposal