Hindfoot alignment view

The hindfoot alignment view is a specialized, weight-bearing radiographic view that examines the hindfoot alignment as part of a foot and ankle instability investigation. 

The long axial view requires no equipment and has higher inter-observer reliability when measuring angular hindfoot alignment ^1,2.

Indications

Suspected varus or vagus malalignment ^1,2.

Patient position

• the patient stands on an upright, radiolucent, stand facing the upright bucky
• patient distributes weight evenly across both feet with the foot in question central to the detector
• the foot is in a neutral position

Detector position

• the detector is in front of the patient, angled 20 degrees slightly under the radiolucent stand

Technical factors

• posterior-anterior, axial projection
• centering point
  • the central beam is angled 20 degrees toward the floor
  • centered at the midpoint of the lateral and medial malleoli
• collimation
  • at least half the tibia and the calcaneum need to be included 
• orientation  
  • ​portrait
•  detector size
  • 18 cm x 24 cm
• exposure​
  • 50-60 kVp
  • 3-6 mAs
• SID
  • 100 cm
• grid
  • no

Image technical evaluation

• clear identification of the most distal portion of the calcaneus 
• clear identification of the anatomical axis of the tibia

Practical points

This projection requires the appropriate equipment i.e. the large, perspex patient stand. Luckily, the alternative projection, the long axial view requires no equipment and has higher inter-observer reliability when measuring angular hindfoot alignment ^1,2.

Whether the image is performed unilateral or bilateral does not impact the reliability of measurement ².

It is important not to collimate tightly on this projection as the anatomical axis of the tibia must be established to calculate the hindfoot alignment. This is calculated via the distance between the anatomical axis of the tibia and the lowest part of the calcaneus (normal sitting at a mean value of 3.2mm) ¹.