Ankle series

The ankle series is comprised of an anteroposterior (AP), mortise and lateral radiograph. The series is often used in emergency departments to evaluate the distal tibia, distal fibula, and the talus; forming the ankle joint.

See approach to an ankle series.

Indications

Ankle radiographs are performed for a variety of indications including ^2-6: 

• ankle trauma
• bony tenderness at the posterior edge or the tip of the lateral malleolus
• bony tenderness at the posterior edge or the tip medial malleolus
• inability to weight bear
• non-traumatic ankle pain

Projections

Standard projections

• AP
  • demonstrates the ankle in the natural anatomical position
• mortise view
  • AP with the foot internally rotated around 10° 
  • internal rotation projects the fibula off the medial tibial plafond resulting uniformity of the joint space allowing for assessment of the distal tibiofibular syndesmosis ³
  • the base of the 5^th metatarsal must be included
• lateral
  • projection 90° to the mortise view
  • demonstrates the calcaneum and talus in full profile
  • must include the base of the 5^th metatarsal

Modified trauma projections

• horizontal beam lateral
  • a modified projection 90° to the mortise view
  • demonstrates the calcaneus and talus in full profile without any limb movement 
  • must include the base of the 5^th metatarsal

Additional projections

If an isolated distal tibial medial malleolus fracture is noted or a significant widening of the mortise joint a knee series should be performed to rule out a combination spiral fracture of the proximal fibula.

Internal or external stress can be conducted to assess for the dynamic widening of the syndesmosis indicating ligamentous injury.