Calc Function

    • Calcs that help predict probability of a diseaseDiagnosis
    • Subcategory of 'Diagnosis' designed to be very sensitiveRule Out
    • Disease is diagnosed: prognosticate to guide treatmentPrognosis
    • Numerical inputs and outputsFormula
    • Med treatment and moreTreatment
    • Suggested protocolsAlgorithm





    Chief Complaint


    Organ System


    Patent Pending

    Ottawa Ankle Rule

    Rules out clinically significant foot and ankle fractures to reduce use of x-ray imaging.
    When to Use
    Why Use

    Patients ≥2 years old with ankle or midfoot pain/tenderness in the setting of trauma.

    The Ottawa Ankle Rule was derived to aid efficient use of radiography in acute ankle and midfoot injuries.

    • Rules have been prospectively validated on multiple occasions in different populations and in both children and adults.
    • Sensitivities range from the high 90-100% range for “clinically significant” ankle and midfoot fractures, defined as fracture or avulsion >3 mm.
    • Specificities are approximately 41% for the ankle and 79% for the foot, though the rule is not designed or intended for specific diagnosis.
    • The Ottawa Ankle Rule is useful for ruling out fracture (high sensitivity), but poor for ruling in fractures (many false positives).

    Tips from the creators at University of Ottawa:

    • Palpate the entire distal 6 cm of the fibula and tibia.
    • Do not neglect the importance of medial malleolar tenderness.
    • “Bearing weight” counts even if the patient limps.
    • Use with caution in patients under age 18.

    Precautions from the creators at University of Ottawa:

    • Clinical judgment should prevail if examination is unreliable for any of the following reasons:
      • Intoxication.
      • Uncooperative patient.
      • Distracting painful injuries.
      • Diminished sensation in legs.
      • Gross swelling which prevents palpation of malleolar tenderness.
    • Always provide written instructions.
    • Encourage follow-up in 5-7 days if pain and ability to walk are not better.
    • Patients without criteria for imaging by the Ottawa Ankle Rule are highly unlikely to have a clinically significant fracture and do not need plain radiographs.
    • Application of the Ottawa Ankle Rule can reduce the number of unnecessary radiographs by as much as 25-30%, improving patient flow in the ED.


    Please fill out required fields.

    Next Steps
    Creator Insights


    • If ankle pain is present and there is tenderness over the posterior 6 cm or tip of the lateral or medial malleolus, then ankle x-ray is indicated.
    • If midfoot pain is present and there is tenderness over the navicular or the base of the fifth metatarsal, then foot x-ray is indicated.
    • If there is ankle or midfoot pain and the patient is unable to take four steps both immediately and in the emergency department, then x-ray of the painful area is indicated.


    • X-ray.
    • RICE plan (Rest, Ice, Compression, Elevation).
    • Splinting/crutches and pain medication, pending outcome.

    Critical Actions

    • Patients who fulfill none of the Ottawa Ankle Rule criteria do not need an ankle or foot x-ray. Those fulfilling either the foot or ankle criteria need an x-ray of the respective body part.
    • Many experts would consider this score “one directional.” Because the rule is sensitive and not specific, it provides a clear guide of which patients not to x-ray if all criteria are met. However, if a patient fails the criteria, need for x-ray can be left to clinical judgment.

    Facts & Figures

    • An ankle x-ray series is only required if there is pain in the malleolar zone AND any of these findings:
      • Bone tenderness at A (posterior edge or tip of lateral malleolus), OR
      • Bone tenderness at B (posterior edge or tip of medial malleolus), OR
      • Inability to bear weight both immediately after injury AND in ED.
    • A foot x-ray series is only required if there is pain in the midfoot zone AND any of these findings:
      • Bone tenderness at C (base of 5th metatarsal), OR
      • Bone tenderness at D (navicular), OR
      • Inability to bear weight both immediately after injury AND in ED.

    Evidence Appraisal

    Original derivation study in 1992:

    • Included non-pregnant patients over age 18 who presented to Ottawa Civic and General Hospitals with a new injury <10 days old.
    • Initial pilot study with 155 patients while full-scale study included 750 patients.
    • Clinically significant fracture = any fracture that was not an avulsion of ≤3 mm across.
    • Initial rules: Age 55 years or greater, inability to bear weight immediately after the injury and for four steps in the emergency department, or bone tenderness at the posterior edge or tip of either malleolus for the ankle. For the foot, criteria included pain in the midfoot and bone tenderness at the navicular bone, cuboid, or the base of the fifth metatarsal.

    Further validation and refinement in 1993:

    • Prospective study of 1,032 patients in the validation and refinement phase of the study with 121 clinically significant fractures.
    • Sensitivity of 100% for significant malleolar zone fractures and 98% for significant midfoot fractures.
    • Rules further refined by removing age cut-off from ankle rule and cuboid tenderness from foot rule, but also added weightbearing criteria to foot rule.
    • Sensitivity of refined rule for both foot and ankle fractures was 100%, but increased ankle specificity to 41% and foot specificity to 79%.
    • An additional 453 patients were then prospectively enrolled in the second phase of the study, where they validated their refined rules, yielding a sensitivity of 100% for both ankle and midfoot fractures.

    Ottawa Ankle Rule in children:

    • A study of 670 children age 2 to 16 at two separate sites found that the rule again had a sensitivity of 100% for both clinically significant ankle and midfoot fractures.
    • Study also found that ankle x-rays could be reduced by 16% and foot x-rays by 29% if the rules were in use at the time of the study.
    • Subsequent meta-analysis of the rule in children found 12 studies with 3,130 patients and 671 fractures, with a pooled sensitivity of 98.5% and overall reduction in x-ray utilization by 24.8%.


    Dr. Ian Stiell

    From the Creator

    Why did you develop the Ottawa Ankle Rule? Was there a clinical experience that inspired you to create this rule for clinicians?
    We found that emergency doctors were ordering many imaging studies for ankle injuries that were then found to be normal. I thought if there were a set a rules with criteria developed by emergency physicians, for emergency physicians, they would help this problem and shorten emergency department wait times and costs.
    What pearls, pitfalls and/or tips do you have for users of the Ottawa Ankle Rule? Are there cases when it has been applied, interpreted, or used inappropriately?
    As a general rule in the emergency department, x-rays are rarely useful because most injuries are soft tissue, and an x-ray does not show ligament injury.
    What recommendations do you have for health care providers once they have applied the Ottawa Ankle Rule besides imaging, or when imaging is negative?
    If the rule states imaging is required, rarely does a patient need both an ankle and foot x-ray, just one or the other or neither. If negative, most patients will heal quickly from a soft tissue ankle injury, but some may require physical therapy.
    What are some situations in which you see clinicians interpreting the rule improperly or incorrectly leading to inappropriate x-ray utilization?
    Sometimes doctors don't properly assess the patient's ability to bear weight on their injured ankle. Most patients can and will walk, but it may take a little encouragement from the physician.

    About the Creator

    Ian Stiell, MD, MSc, FRCPC, is Professor and Chair, Department of Emergency Medicine, University of Ottawa; Distinguished Professor and University Health Research Chair, University of Ottawa; Senior Scientist, Ottawa Hospital Research Institute; and Emergency Physician, The Ottawa Hospital. He is internationally recognized for his research in emergency medicine with a focus on the development of clinical decision rules and the conduct of clinical trials involving acutely ill and injured patients treated by prehospital services and in emergency departments. He is best known for the development of the Ottawa Ankle Rule, the Canadian C-Spine Rule, and Canadian CT Head Rule and as the Principal Investigator for the landmark OPALS Studies for prehospital care. Dr. Stiell is the Principal Investigator for 1 of 3 Canadian sites in the Resuscitation Outcomes Consortium (ROC) which is funded by CIHR, NIH, HSFC, AHA, and National Defence Canada. Dr. Stiell is a Member of the Institute of Medicine of the U.S. National Academies of Science.

    To read more about Dr. Stiell's work, visit his website.

    To view Dr. Ian Stiell's publications, visit PubMed

    Content Contributors
    About the Creator
    Dr. Ian Stiell
    Partner Content
    Content Contributors