Ankle (AP view)

The ankle AP view is part of a three view series, and visualizes the distal tibia, distal fibula, proximal talus and proximal fifth metatarsal.

Indications

The true anteroposterior view of the ankle is often performed in the setting of ankle trauma and suspected ankle fractures in addition to the lateral and mortise views of the ankle.

Other indications include:

• assessment of fragment position and implants in postoperative follow up
• evaluation of fracture healing
• evaluation of tibiofibular clear space and overlap in suspected syndesmotic injury
• evaluation of hindfoot deformities

In addition, this view can show bony diseases or lesions of the distal lower leg, talus and proximal fifth metatarsal.

Patient position

• the patient may be supine or sitting upright with their leg straighten on the table
• the foot is in dorsiflexion
• the toes will be pointing directly toward the ceiling

Technical factors

• anteroposterior projection
• centering point
  • the midpoint of the lateral and medial malleoli
• collimation
  • laterally to the skin margins
  • superior to examine the distal third of the tibia and fibula
  • inferior to the proximal aspect of the metatarsals
• orientation  
  • portrait
• detector size
  • 24 cm x 30 cm
• exposure
  • 50-60 kVp
  • 3-5 mAs
• SID
  • 100 cm
• grid
  • no

Image technical evaluation

• the distal fibula should be slightly superimposed the distal tibia
• the lateral and medial malleoli of the distal fibula and tibia are in profile
• the tibiotalar joint space should be open, yet the full mortise joint should not be visualized on the AP

Practical points

This view can be thought of as the literal anteroposterior of the ankle. Most patients will naturally place their foot in this position.

Although dorsiflexion is essential in both the AP and the mortise view it should be noted that during trauma this may not be possible.

See also

• ankle fractures