Ottawa Ankle Rules Calculator

Ottawa Ankle Rules Calculator for Emergency. A trigger supports the relevant radiographic series, not a diagnosis of fracture. No trigger means only that the specified rule combination was not met. Document why clinical judgment leads to imaging despite a negative rule, and arrange reassessment when the course is not improving as expected.

For shared guidance on choosing a tool and documenting results, read the clinical calculator workflow.

How this calculator works

Ankle and midfoot decisions are separate Boolean rules, not a summed injury score. Malleolar-zone pain must accompany qualifying medial/lateral bone tenderness or inability to bear weight at both required times. Midfoot-zone pain must accompany navicular or fifth-metatarsal-base tenderness, or the same weight-bearing finding. Every observation requires an explicit response; an untouched form cannot become a negative examination.

When to use this calculator

Use after examining an alert adult with a recent blunt injury and reliable findings. This implementation deliberately restricts use to adults and injuries within seven days; it does not cover all populations studied with the Ottawa rules. An open injury, deformity, impaired circulation or unreliable examination requires a direct clinical pathway.

Inputs used

  • Alert adult, reliable examination, acute blunt injury within 7 days, no urgent exclusion?
  • Pain in the malleolar zone?
  • Pain in the midfoot zone?
  • Bone tenderness at the posterior distal 6 cm or tip of the lateral malleolus?
  • Bone tenderness at the posterior distal 6 cm or tip of the medial malleolus?
  • Navicular bone tenderness?
  • Tenderness at the base of the fifth metatarsal?
  • Unable to take four weight-bearing steps both immediately after injury and at examination?

Clinical interpretation

A trigger supports the relevant radiographic series, not a diagnosis of fracture. No trigger means only that the specified rule combination was not met. Document why clinical judgment leads to imaging despite a negative rule, and arrange reassessment when the course is not improving as expected.

Worked example

Suppose malleolar pain and qualifying lateral bone tenderness are present, while midfoot pain is absent. The ankle branch supports radiography and the foot branch is not applicable. If midfoot pain and navicular tenderness are also present, both regions meet their respective rules. Tenderness alone without the corresponding pain zone is not an independent trigger in this logic.

Limitations and safety notes

Anatomical localization and the examination cannot be verified by software. The rule is not a tendon, ligament, neurovascular or all-foot-fracture assessment. Official diagrams are linked through source organizations rather than reproduced; this original text and logic are not an endorsed Ottawa implementation.

Frequently asked questions

Why are there two results?

The malleolar and midfoot rules address different radiographic regions. One can be positive while the other is inapplicable.

Does limping count as inability to bear weight?

The source assessment concerns taking four weight-bearing steps, not walking comfortably. Confirm performance immediately after injury and at examination.

Does a negative result diagnose a sprain?

No. It does not establish the cause of pain or exclude injuries outside the rule's target.

References

  • OHRI developer group: adult conservative scope and intended radiography decision role. https://ohri.ca/en/find-researcher/istiell
  • British Columbia official guideline: zone-specific Ottawa ankle/midfoot logic and limitations; historical guideline, not a newly issued 2026 recommendation. https://www2.gov.bc.ca/gov/content/health/practitioner-professional-resources/bc-guidelines/ankle-injury

Editorial review and citation methodology

Maintained by the Quick Medical Calculator Editorial Team. Content record date: September 9, 2026. A content date is not evidence of independent clinical review. Individual clinical sign-off is not recorded on this page.

  • Prefer original validation studies for scoring systems and prediction tools.
  • Use current specialty society guidance, transplant allocation policy, public health guidance, or regulator resources when they govern clinical use.
  • Include limitations and safety notes when a calculator is population-specific, context-dependent, or unsuitable as a standalone decision tool.

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