What are the Ottawa ankle criteria (Ottawa ankle rules) for determining when an X-ray is needed for a patient with ankle pain?

Ottawa Ankle Rules for Determining Need for X-rays in Ankle Injuries

The Ottawa Ankle Rules state that ankle radiographs are only required when there is pain in the malleolar region AND either bone tenderness along the distal 6 cm of the posterior edge of the medial or lateral malleolus, OR inability to bear weight for four steps both immediately after injury and in the emergency department. 1, 2

Criteria for Ankle X-rays

When evaluating ankle injuries, order radiographs only if the patient has:

• Pain in the malleolar region AND one or both of:
  • Bone tenderness at the posterior edge of the distal 6 cm of either malleolus
  • Inability to bear weight for four steps both immediately after injury and in the emergency department

Criteria for Midfoot X-rays

For midfoot injuries, radiographs are required only when:

• Pain in the midfoot AND one or more of:
  • Point bone tenderness at the navicular bone
  • Point bone tenderness at the base of the fifth metatarsal
  • Inability to bear weight for four steps both immediately after injury and in the emergency department 1, 2

Exclusionary Criteria

The Ottawa Ankle Rules should NOT be used or should be used with great caution in the following scenarios 1, 2:

• Penetrating trauma
• Pregnancy
• Skin wounds
• Patients transferred with radiographs already taken
• Injuries >10 days old
• Return visits for continued traumatic pain
• Polytrauma
• Altered sensorium
• Neurologic abnormality affecting the foot/ankle
• Underlying bone disease

Effectiveness and Benefits

• The Ottawa Ankle Rules have demonstrated 99% sensitivity for detecting ankle and midfoot fractures 1
• Specificity is approximately 26% for combined evaluation of ankle and midfoot 1
• Implementation can reduce unnecessary radiographs by 31-35% 3, 4
• The rules are validated for both adults and children over 5 years of age 1, 2

Special Considerations

• Adding the criterion of swelling increases sensitivity to 100% and specificity to 55% for the malleolar zone 1
• Some studies suggest modifying the rules to mandate imaging for all patients ≥65 years of age with ankle pain, as this improves sensitivity in the geriatric population 5
• Standard radiographs for ankle injuries should include anteroposterior, lateral, and mortise views 2
• The Ottawa Ankle Rules may help identify occult fractures not visible on standard radiographs 4

Implementation Tips

• Document compliance with Ottawa criteria in clinical notes
• Include relevant Ottawa criteria when requesting radiographs
• Clinical judgment should supersede the rules when there is strong suspicion of fracture 2
• The rules are designed as a screening tool with high sensitivity to rule out fractures, not to definitively diagnose them

The Ottawa Ankle Rules provide a reliable, evidence-based approach to determining the need for radiography in ankle and midfoot injuries, reducing unnecessary imaging while maintaining high sensitivity for clinically significant fractures.