Imaging Case of the Week 253 Answer

The frontal wrist x-ray shows a widened scapholunate interval. Normal interval is 2mm. In the x-ray shown, it is 4 mm. This abnormal widening represents the ‘Terry Thomas Sign’ indicative of scapholunate dissociation. The disrupted scapholunate ligament has also caused foreshortening of the scaphoid giving rise to a ‘signet ring scaphoid sign’.

The lateral view of the wrist shows an abnormal dorsal tilting of the lunate, indicating the presence of DISI (dorsal intercalated segmental insufficiency).

MRI images from the same patient showing the injury clearly:

This patient underwent operative management.


Fundamentals of Diagnostic Radiology by Brant and Helms, 4th edition & Carpal instability chapter on Radiology assistant (here)

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