Ankle Lateral (Mediolateral) is a radiography positioning projection of the Lower Extremity. Patient lateral recumbent on affected side, CR perpendicular to ankle. SID 40". The centering point is located ankle joint space with lateral border of foot on ir.. The central ray is perpendicular to the ankle joint in true lateral position.. Image-quality criteria include ankle joint space open and clearly visible in true lateral., distal tibia and fibula, talus, and calcaneus all included.. Standard exposure ranges from 60 to 70 kVp, 4 to 7 mAs, at an SID of 40 inches (102 cm).
Anatomy demonstrated
- Distal tibia and fibula in true lateral.
- Medial and lateral malleoli superimposed.
- Ankle mortise (talocrural) joint space.
- Entire talus within the mortise.
- Anterior and posterior borders of talar dome.
- Calcaneus shown beneath the talus.
Patient preparation
- Verify patient identity using two identifiers.
- Remove footwear, socks, and any radiopaque foot jewelry.
- Position the patient lateral recumbent on the affected side.
- Place the lateral border of the foot on the IR.
- Flex the knee for patient comfort and anatomical stability.
Position & centering point
Ankle joint space with lateral border of foot on IR.
Central ray
Perpendicular to the ankle joint in true lateral position.
Exposure / technique
- kVp
- 60–70
- mAs
- 4–7
- SID
- 40" (102 cm)
- Notes
- Position patient on affected side. Flex knee for stability and patient comfort.
Image-quality criteria
- Ankle joint space open and clearly visible in true lateral.
- Distal tibia and fibula, talus, and calcaneus all included.
- Medial and lateral malleoli superimposed (overlapped in true lateral).
- Anterior and posterior borders of the talar dome clearly shown.
- Bone trabeculae sharp, no motion blur.
- Collimation: 1 inch on all sides of ankle, 8 inches lengthwise.
Common errors / ARRT traps
- 1 Medial or lateral rotation distorts the true lateral projection.
- 2 Plantar flexion or dorsiflexion tilts the ankle mortise.
- 3 Off-centered CR clips the malleoli or ankle joint.
- 4 Foot not fully lateral causes the malleoli to separate.
Clinical indications
- Trauma evaluation for suspected ankle fracture or dislocation.
- Assessment of anterior or posterior tibial malleolar fracture.
- Evaluation of talofibular ligament injuries.
Aligned to the 2025 ARRT Content Specifications.