Ankle (weight-bearing lateral view)

The weight-bearing lateral view of the ankle is a specialized projection that places the joint under normal weight-bearing conditions.  The projection is utilized to assess the joint under stress and better demonstrate structural and functional deformities. 

Indications

This projection is utilized to assess the structural integrity of the ankle joint. If the patient is able, weight-bearing views should be performed in acute and follow-up settings ¹. 

Ultimately the radiographer will determine if the projection is safe to perform.

Patient position

• the patient is standing on an upright stand with the ankle in question parallel to the detector 

• patient is distributing weight evenly 

  • have something for the patient to hold onto, especially if they are unsteady on their feet

Technical factors

• mediolateral projection

• centering point

  • the bony prominence of the medial malleolus of the distal tibia

• collimation

  • anteriorly from the hindfoot to the 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

• distal fibula should be superimposed by the posterior portion of the distal tibia

• talar domes should be superimposed, allowing for adequate inspection of the superior articular surface of the talus

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

Useful measurements

• posterior tibial line

• Bohler angle 

• the crucial angle of Gissane

Practical points

Superior-inferior malalignment of the superior aspect of the talus is the resultant of the tibia not lying parallel to the image receptor. 

Anterior-posterior malalignment of the talar domes is due to over or under rotation of the foot. 

Although this projection is helpful to assess lower limb injuries better, it must be performed safely. Explain and demonstrate to the patient how it is performed. Give them something to hold on to. If the exam does not feel safe, explore alternative methods such as a standard, supine lateral projection.