To obtain an AP ankle projection, which adjustment should be made to the foot?

To obtain an AP ankle projection, which adjustment should be made to the foot?

• A. Dorsiflex the foot
• B. Extend the foot
• C. Angle the tube 15 cephalad
• D. Angle the tube 5-10 medial

Answer: (A)

Dorsiflexing the foot is needed to get a true AP view of the ankle. When the foot is flexed upward so the plantar surface is near perpendicular to the leg, the ankle joint aligns with the leg and the tibia, fibula, and talus sit with minimal distortion. This position reduces soft-tissue and joint-space distortion and prevents the talus from being misplaced relative to the distal tibia, so the ankle joint and surrounding structures are shown accurately on the AP projection. Extending the foot without dorsiflexion won’t bring the joint into that same true alignment and can still leave the mortise and joint spaces distorted. Angling the x-ray tube cephalad or medially would distort the projection rather than improve alignment of the ankle structures on an AP view.

Dorsiflexing the foot is needed to get a true AP view of the ankle. When the foot is flexed upward so the plantar surface is near perpendicular to the leg, the ankle joint aligns with the leg and the tibia, fibula, and talus sit with minimal distortion. This position reduces soft-tissue and joint-space distortion and prevents the talus from being misplaced relative to the distal tibia, so the ankle joint and surrounding structures are shown accurately on the AP projection.

Extending the foot without dorsiflexion won’t bring the joint into that same true alignment and can still leave the mortise and joint spaces distorted. Angling the x-ray tube cephalad or medially would distort the projection rather than improve alignment of the ankle structures on an AP view.