Imaging Case of the Week 220 Answer

The frontal wrist x-ray shows a scaphoid waist fracture.

scaphoid waist fractureThe lateral wrist x-ray shows an increased scapholunate angle, which is the angle between the following two lines:

  • scaphoid axis – a line joining the most ventral point of the proximal and distal poles of the scaphoid.
  • lunate axis – a line joining the midpoint of the proximal and distal articular surfaces of the lunate.

Normally, the scapholunate angle is approx. 30-60 degrees. An increased scapholunate angle indicates DISI (dorsal intercalated segmental insufficiency), which is a form of carpal instability.

increased scapholunate angle

DISI

It is important to diagnose this injury (DISI) so that the patient can be referred to a specialist soon after the injury.

Our patient had an obvious scaphoid fracture with DISI and underwent operative management.

 

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