Ankle (weight-bearing mortise view)

Last revised by Weiling Tan on 4 Apr 2023

The weight-bearing mortise (mortice is equally correct) 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. 

Mortise and mortice are variant spellings and equally valid 1.

This weight-bearing 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 2

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

The mortice is the most pertinent for assessing the articulation of the tibial plafond and two malleoli with the talar dome, otherwise known as the mortise joint of the ankle 3,4.

The most common indication is a trauma to the ankle in the setting of suspected ankle fractures and/or dislocations including talar fractures.

Other indications include:

  • assessment of fragment position and implants in postoperative follow up
  • evaluation of fracture healing
  • osteochondral injuries of the talus
  • osteoarthritis of the ankle
  • the patient is standing on an upright stand with the ankle in question perpendicular to the detector
  • the leg rotated internally 15° to 20°, thus aligning the intermalleolar line parallel to the detector
    • this usually results in the 5th toe being directly in line with the center of the calcaneum
  • anteroposterior projection
  • centering point
    • the midpoint of the lateral and medial malleoli
  • collimation
    • laterally to the skin margins
    • superiorly 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
  • the lateral and medial malleoli of the distal fibula and tibia, respectively, should be seen in profile
  • uniformity of the mortise joint should be seen without any superimposition of either malleolus
  • the base of the 5th metatarsal must be included in the inferior aspect of the image

Aligning the 5th toe to the center of the calcaneus is a practical way to gauge the optimal internal rotation needed to demonstrate the mortise joint. Another way to ensure correct positioning is by rotating the leg internally until the central line of the collimation field is in line with the 5th metatarsal.

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 projection.

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Cases and figures

  • Case 1: chronic erosive arthropathy
    Drag here to reorder.
  • Case 2: normal
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