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Ankle XRay
Aka: Ankle XRay, Ottawa Ankle Rule, Low Risk Ankle Rule
- Technique: Views
- Lateral ankle
- Anteroposterior ankle
- Ankle Mortis view
- Anteroposterior view
- Leg internally rotated 15 to 20 degrees
- Indications: Ottawa Ankle Rules in Acute Ankle Sprain (Over age 5 years old)
- Ankle XRay not needed if both are true:
- Able to ambulate at injury or in ER for 4 steps
- No pain over distal posterior 6 cm (2.4 inches) of tibia, fibula
- Foot Xray not needed for mid-Foot Pain if both true:
- Able to ambulate at injury or in ER for 4 steps
- No pain at fifth Metatarsal base and Tarsal Navicular
- Efficacy
- Test Sensitivity for Malleolar Fracture: 95%
- Requires alert adult or child age 5 or older
- Injury within prior 10 days
- Indications: Low Risk Ankle Rule (children over age 3 years old)
- Ankle XRay is not needed if:
- No marked swelling, deformity or malalignment AND
- No pathologic Fracture risk AND
- Tenderness is limited to distal fibula (distal to anterior tibial joint line) and lateral ligaments
- Efficacy
- Children must be over age 3 years old
- Finds high risk injury (e.g. distal tibia, proximal fibula, ankle dislocation) in 98-100% of those age >3 years old
- Misses nondisplaced distal fibula avulsion Fractures and Salter-Harris I and II Fractures
- References
- Boutis (2013) CMAJ 185(15):E731-8 +PMID:23939215 [PubMed]
- Ramasubbu (2015) Pediatr Emerg Care 31(10):685-7 +PMID:26196362 [PubMed]
- Imaging: Pitfalls
- Growth Plate Fracture in adolescent
- May be missed on Ankle XRay
- Consider if pain over lateral malleolus (fibula)
- Ankle Syndesmotic Sprain (High Ankle Sprain)
- Tibiofibular clear space widening >6 mm
- Ankle mortise
- Space around the talus should be consistent (symmetric) at its margin between the tibia and fibula
- Os Trigonum is a normal variant (lateral xray)
- Os Trigonum is an Ossification Center posterior to the talus
- Normal variant seen on lateral Ankle XRay in up to 14% of patients
- References
- Labovitz (1998) Foot Ankle Int 19:661-7 [PubMed]
- Stiel (1994) JAMA 271:827-32 [PubMed]