Ankle (lateral view)

The ankle lateral view is part of a three view ankle series; this projection is used to assess the distal tibia and fibula, talus, navicular, cuboid, the base of the 5^th metatarsal and calcaneus.

Indications

This projection aids in evaluating fractures, dislocations and joint effusions surrounding the ankle joint, and helps to assess the severity of a calcaneal fracture by measuring the Böhler angle and Gissane angle.

Patient position

• patient is in a lateral recumbent position on the table
• the lateral aspect of the knee and ankle joint should be in contact with the table resulting in the tibia lying parallel to the table
• the leg can be bent or straight 
• foot in dorsiflexion 
• place the opposite leg behind the injured limb to avoid over-rotation

Technical factors

• mediolateral projection
• centering point
  • the bony prominence of the medial malleolus of the distal tibia
• collimation
  • anteriorly from the hindfoot to extent of the skin margins of the most posterior portion of the calcaneus
  • superior to examine the distal third of the tibia and fibula
  • inferior to the skin margins of the plantar aspect of the foot
• orientation  
  • portrait
• detector size
  • 18 cm x 24 cm
• exposure
  • 50-60 kVp
  • 3-5 mAs
• SID
  • 100 cm
• grid
  • no

Image technical evaluation

The distal fibula should be superimposed by the posterior portion of the distal tibia.

The talar domes should be superimposed allowing for adequate inspection of the superior articular surface of the talus.

The joint space between the distal tibia and the talus is open and uniform.

Practical points

Superior-inferior malalignment of the superior aspect of the talus is resultant of the tibia not lying parallel to the image receptor. To adjust this, either lower the knee to suit the ankle better or place the ankle on a small wedge sponge to better suit the knee. 

Anterior-posterior malalignment of the talar domes is due to over or under rotation of the foot. To adjust this, check that the heel or the toes are not raised too far up. If the patient cannot correct this position, it can be aided with a small wedge sponge. 

In trauma, it may not be possible to place the patient as above, in these cases, the same principles can be applied with a modified horizontal beam view. The patient can remain supine with an image receptor placed vertically adjacent to the lateral aspect of the upright ankle, and the x-ray beam is directed horizontally, centered at the bony prominence of the medial malleolus of the distal tibia.