AP Medial Oblique Ankle is a radiography positioning projection of the Lower Extremity. Supine, ankle internally rotated 45 degrees. SID 40". The centering point is located ankle joint, with foot internally rotated 45 degrees.. The central ray is perpendicular to the ankle joint.. Image-quality criteria include medial and lateral malleoli visible in profile with minimal superimposition., tibiotalar joint space open and clearly visualized.. Standard exposure ranges from 60 to 70 kVp, 4 to 7 mAs, at an SID of 40 inches (102 cm).
Anatomy demonstrated
- Medial malleolus of tibia in profile.
- Lateral malleolus of fibula in profile.
- Talus with clear talar dome visualization.
- Navicular and cuboid bones.
- Distal tibia and fibula.
- Tibiotalar joint space.
Patient preparation
- Verify patient identity using two identifiers.
- Remove shoes and any radiopaque items from the foot and ankle.
- Position patient supine with ankle extended over the IR.
- Internally rotate the foot 45 degrees to free the lateral malleolus and open the distal tibiofibular joint.
- Ensure the ankle joint is centered over the IR.
Position & centering point
Ankle joint, with foot internally rotated 45 degrees.
Central ray
Perpendicular to the ankle joint.
Exposure / technique
- kVp
- 60–70
- mAs
- 4–7
- SID
- 40" (102 cm)
- Notes
- Tabletop technique. No grid required for ankle projections.
Image-quality criteria
- Medial and lateral malleoli visible in profile with minimal superimposition.
- Tibiotalar joint space open and clearly visualized.
- Distal tibia, fibula, talus, and navicular all included.
- Distal tibiofibular joint open with the lateral malleolus clear of the talus.
- Bone trabeculae sharp, no motion blur.
- Collimation 1 inch on all sides, 1.5 inches beyond ankle.
Common errors / ARRT traps
- 1 Insufficient internal rotation leaves the lateral malleolus superimposed on the talus.
- 2 Excessive rotation closes the tibiotalar joint space.
- 3 Off-centered CR clips the medial malleolus or tarsals.
- 4 Foot inversion or eversion changes the joint angle.
Clinical indications
- Ankle fracture or sprain evaluation.
- Assessment of the distal tibiofibular joint and lateral malleolus.
- Arthritis or degenerative joint disease of the ankle.
- Post-operative follow-up of ankle fixation hardware.
Aligned to the current ARRT Radiography Content Specifications.