AP Weight-Bearing Ankle is a radiography positioning projection of the Lower Extremity. Upright standing on low platform, feet slightly apart. SID 40". The centering point is located ankle joint at mid-line, weight-bearing position.. The central ray is perpendicular to the ankle joint.. Image-quality criteria include both ankles symmetrically positioned and centered on ir., foot alignment straight without inversion or eversion.. Standard exposure ranges from 60 to 70 kVp, 4 to 7 mAs, at an SID of 40 inches (102 cm).
Anatomy demonstrated
- Talar dome in true AP relationship.
- Distal tibia and fibula.
- Medial and lateral malleoli symmetrically positioned.
- Full tibiotalar joint space.
- Proximal tarsal bones under weight-bearing load.
- Overall foot and ankle alignment.
Patient preparation
- Verify patient identity using two identifiers.
- Remove shoes and any radiopaque items from the foot and ankle.
- Have patient stand upright on both feet on a low platform.
- Position feet slightly apart for balance and stability.
- Ensure weight distributed equally on both feet.
Position & centering point
Ankle joint at mid-line, weight-bearing position.
Central ray
Perpendicular to the ankle joint.
Exposure / technique
- kVp
- 60–70
- mAs
- 4–7
- SID
- 40" (102 cm)
- Notes
- Weight-bearing technique shows foot alignment and ankle stability under load.
Image-quality criteria
- Both ankles symmetrically positioned and centered on IR.
- Foot alignment straight without inversion or eversion.
- Talar dome and ankle joint clearly visualized.
- Full ankle joint and surrounding anatomy visible.
- Talus, distal tibia, fibula, and foot all included.
- Collimation 1 inch on sides, 1.5 inches above and below ankle.
Common errors / ARRT traps
- 1 Unequal weight distribution distorts ankle alignment.
- 2 Inversion or eversion of foot changes angular relationships.
- 3 Off-centered CR clips distal tibia or foot structures.
- 4 Patient leaning to one side rotates ankle out of true AP.
Clinical indications
- Evaluation of ankle stability under weight-bearing stress.
- Assessment of talus subluxation or ligamentous insufficiency.
- Chronic ankle instability or inversion sprain sequelae.
- Post-operative alignment verification with weight-bearing loads.
Aligned to the 2025 ARRT Content Specifications.