Ottawa Ankle Rules: When to Order an Ankle X-Ray

Knowing when to order X-rays, or even what to order, can be confusing. The Ottawa Ankle Rules, developed by Stiell, specifies the criteria to be met before ordering X-rays for a patient presenting with an acute ankle injury.10,11,13,14 The instructions and associated figure below layout these guidelines.

Ottawa Ankle Rules

Using the diagram below we can determine when an ankle series is required. The rule’s reported sensitivity is 1.0, so X-rays are necessary if any of the below are met:

A. There is any pain in the malleolar zone and any of the following:

  1. Bone tenderness at A
  2. Bone tenderness at B
  3. Inability to take 4 steps both immediately and in the emergency department

B. There is any pain in the midfoot zone and any of the following:

  1. Bone tenderness at C
  2. Bone tenderness at D
  3. Inability to take 4 steps both immediately and in the emergency department

If neither of these criteria is present, no imaging is needed.



By knowing these rules and using them correctly, you can:

  • Appropriately treat and refer patients
  • Keep costs of health care down
  • Decrease needless imaging
  • Decrease harm to the patient by excess radiation exposure
  • Prevent unnecessary interventions

Improved Outcomes

This is just one example of how clinical criteria can help you with your decision to order imaging. Whether it’s the Ottawa Ankle Rules or another clinical decision directive, if you use and understand these rules, you can easily improve your patient outcomes.

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