Ottawa Ankle Rules

A validated clinical decision rule to determine whether radiography is required for acute ankle and midfoot injuries. Safely reduces unnecessary X-rays by up to 40%.

Important Clinical Disclaimer: The Ottawa Ankle Rules is intended for use by qualified healthcare professionals only. It is for educational and informational purposes and should not replace clinical judgement. Always interpret results alongside the full clinical picture and follow your local guidelines and protocols.
Ottawa Ankle Rules Assessment
Prerequisites: The Ottawa Ankle Rules apply to patients presenting with pain in the malleolar zone (ankle) or midfoot zone following trauma.
Ankle X-ray Series

An ankle X-ray is required if there is any pain in the malleolar zone AND any of the following:

Distal 6cm of fibula
Distal 6cm of tibia
Unable to take 4 steps immediately after injury AND in the emergency department
Foot X-ray Series

A foot X-ray is required if there is any pain in the midfoot zone AND any of the following:

Styloid process on lateral aspect of foot
Medial midfoot
Unable to take 4 steps immediately after injury AND in the emergency department
Anatomical Zones
Malleolar Zone (Ankle):
  • Lateral malleolus: Distal 6cm of fibula, including posterior edge and tip
  • Medial malleolus: Distal 6cm of tibia, including posterior edge and tip
Midfoot Zone:
  • Base of 5th metatarsal: Styloid process (lateral aspect)
  • Navicular bone: Medial midfoot
Key point: Palpate the posterior edge of the malleoli (not just the tip) - this is the most commonly missed examination finding.
About the Rules

The Ottawa Ankle Rules were developed by Stiell et al. in 1992 at the Ottawa Civic Hospital to reduce unnecessary radiography for ankle and midfoot injuries.

Performance:
  • Sensitivity: 98-100% for significant fractures
  • Specificity: ~40%
  • Negative predictive value: ~99.6%
  • Reduces X-rays by 30-40% without missing clinically significant fractures

When to Apply the Ottawa Ankle Rules

Apply Rules If:
  • Acute injury (within 10 days)
  • Pain in the malleolar or midfoot zone
  • Patient is aged 2-65 years (some sources say >5 years)
  • Patient is alert and cooperative
  • No other distracting painful injuries
  • Not intoxicated
Do NOT Apply If:
  • Injury >10 days old
  • Isolated skin injuries (abrasions, lacerations)
  • Patient intoxicated or uncooperative
  • Diminished sensation (e.g., neuropathy)
  • Distracting painful injuries
  • Pregnancy (relative - consider clinical judgement)
  • Head injury with reduced GCS

Examination Technique

Palpation Tips
  1. Explain the examination to the patient
  2. Start away from the injury to build trust
  3. Palpate the posterior edge of each malleolus (distal 6cm), not just the tip
  4. Palpate the base of 5th metatarsal (lateral foot)
  5. Palpate the navicular (medial midfoot)
  6. Watch for bony tenderness - not just soft tissue/ligamentous pain
Weight-Bearing Assessment
  • Ask about ability to weight bear immediately after injury
  • Assess ability to take 4 steps (can limp, but must transfer weight to each foot twice)
  • This must be assessed at the time of examination
  • If patient cannot weight bear at all, criterion is positive
Note: "4 steps" means transferring weight to each foot twice - limping is acceptable.

Frequently Asked Questions

The Ottawa Ankle Rules have been extensively validated:

  • Sensitivity: 98-100% - virtually no significant fractures are missed
  • Specificity: ~40% - many patients without fractures will still get X-rays
  • Negative predictive value: ~99.6%

The rules are designed to be highly sensitive (catch all fractures) at the cost of some specificity. A negative result (no criteria met) effectively rules out a significant fracture.

The Ottawa Ankle Rules have been validated in children, with some considerations:

  • Originally validated in adults, but subsequent studies support use in children aged >5 years
  • Some centres use age >2 years as the lower limit
  • Examination may be more challenging in young children
  • Growth plate injuries should be considered in skeletally immature patients

NICE supports use in children who can be reliably assessed. Use clinical judgement for very young children.

If the patient has bony tenderness at any of the specified locations (posterior malleoli, base of 5th metatarsal, navicular), an X-ray is indicated regardless of weight-bearing ability.

The criteria are additive - any ONE positive criterion means X-ray is indicated. Weight-bearing ability alone does not rule out the need for imaging.

The Ottawa Ankle Rules are designed to detect fractures, not ligamentous injuries. They may not reliably identify:

  • High ankle sprains (syndesmotic injuries)
  • Maisonneuve fractures (proximal fibula)
  • Isolated ligamentous injuries

If clinical suspicion for syndesmosis injury is high (e.g., pain with external rotation, squeeze test positive), consider X-ray regardless of Ottawa criteria, and include views of the full fibula if Maisonneuve fracture is suspected.

NICE Clinical Knowledge Summaries (CKS) on sprains and strains recommends:

  • Use the Ottawa Ankle Rules to determine need for X-ray
  • If no criteria are met, fracture is highly unlikely and X-ray is not indicated
  • Provide advice on PRICE (Protection, Rest, Ice, Compression, Elevation)
  • Advise return if symptoms not improving after expected timeframe

The rules are endorsed by NICE, Royal College of Emergency Medicine, and most UK emergency departments.

Disclaimer

This calculator is provided for educational and informational purposes only. It is not intended to be a substitute for professional medical advice, diagnosis, or treatment.

  • Always seek the advice of a qualified healthcare provider with any questions regarding a medical condition.
  • Never disregard professional medical advice or delay seeking it because of information from this tool.
  • Clinical decision-making should always incorporate the full clinical context, patient preferences, and local protocols.
  • The creators of this tool accept no liability for decisions made based on its output.

If you are a patient: please discuss any results with your healthcare provider. This tool is designed for use by medical professionals and may not be appropriate for self-assessment.

References

  1. Stiell IG, et al. (1992). A study to develop clinical decision rules for the use of radiography in acute ankle injuries. Annals of Emergency Medicine, 21(4), 384-390.
  2. Stiell IG, et al. (1994). Implementation of the Ottawa ankle rules. JAMA, 271(11), 827-832.
  3. Bachmann LM, et al. (2003). Accuracy of Ottawa ankle rules to exclude fractures of the ankle and mid-foot: systematic review. BMJ, 326(7386), 417.
  4. Dowling S, et al. (2009). Accuracy of Ottawa Ankle Rules to exclude fractures of the ankle and midfoot in children: a meta-analysis. Academic Emergency Medicine, 16(4), 277-287.
  5. NICE CKS (2023). Sprains and strains. National Institute for Health and Care Excellence.