II. Technique: Views
- Lateral ankle
- Anteroposterior ankle
-
Ankle Mortis view
- Anteroposterior view
- Leg internally rotated 15 to 20 degrees
III. 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
IV. 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
V. 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