What is the Ottawa ankle rule?

Ottawa Ankle Rules Explained

The Ottawa Ankle Rules are clinical decision guidelines that determine when radiographs are necessary for patients with acute ankle and foot injuries, with 99% sensitivity for detecting fractures while reducing unnecessary imaging by approximately 30%. 1

Ankle Rules

• An ankle X-ray series is required only when there is:
  • Pain in the malleolar region AND either:
    • Bone tenderness along the distal 6 cm of the posterior edge or tip of either malleolus, OR
    • Inability to bear weight for four steps both immediately after injury and in the emergency department 1

Foot Rules

• A foot X-ray series is required only when there is:
  • Pain in the midfoot AND any one of the following:
    • Point bone tenderness of the navicular bone
    • Point bone tenderness of the base of the fifth metatarsal
    • Inability to bear weight or walk 4 steps immediately after injury or in the emergency department 1

Clinical Performance

• The Ottawa Ankle Rules have a sensitivity of 96.8-100% for detecting clinically significant fractures 1
• Adding swelling as a criterion increases sensitivity to 100% for the malleolar zone 1
• Specificity ranges from 16-51%, which still allows for significant reduction in unnecessary radiographs 1, 2

Implementation Benefits

• Reduces radiography in acute ankle/foot injuries by approximately 16-35% 3, 4
• Generates cost savings without compromising quality of care 3
• Facilitates faster discharge and reduces unnecessary radiation exposure 2

Exclusionary Criteria

• The Ottawa Rules should not be used or should be used with great caution in patients with:
  • Penetrating trauma
  • Pregnancy
  • Skin wounds
  • Patients transferred with radiographs already taken
  • Injuries >10 days old
  • Return visits for continued traumatic foot pain
  • Polytrauma
  • Altered sensorium
  • Neurologic abnormality affecting the foot
  • Underlying bone disease 1

Age Considerations

• The rules are validated for patients >5 years of age 1, 5
• Studies have confirmed 100% sensitivity for clinically significant fractures in children aged 5-16 years 4
• For children between 5-12 years, radiographs may be beneficial despite lack of clinical symptoms according to some guidelines 6

Standard Radiographic Views When Indicated

• When X-rays are indicated based on the Ottawa Ankle Rules, three standard views should be obtained:
  • Anteroposterior
  • Lateral
  • Mortise views 1
• The views should include the base of the fifth metatarsal bone distal to the tuberosity 1

Clinical Pitfalls to Avoid

• Failing to assess all criteria before ruling out the need for imaging 1
• Not considering age-specific modifications for elderly patients 1
• Applying the rules to patients with gross deformity, palpable mass, penetrating injury, prosthetic hardware, unreliable clinical history, or altered mental status 6
• Missing the only clinically significant fracture when the rules are applied by non-physician providers without physician assessment 5

Prognosis

• The ability to walk again within 48 hours after trauma indicates a good prognosis 1
• After 1 year, 5% to 33% of patients with lateral ankle injuries still have pain and complaints of instability 6
• 3% to 34% experience a recurrent ankle sprain within 1 year 6