Ottawa Ankle Rule
Why Use
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.
When to Use
Patients ≥2 years old with ankle or midfoot pain/tenderness in the setting of trauma.
Pearls / Pitfalls
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.
Management
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.
Advice
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.
More Information
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.