UMEM Educational Pearls

Category: Visual Diagnosis

Title: What's the Diagnosis? Case submitted by Dr. Ryan Spangler

Posted: 5/20/2013 by Haney Mallemat, MD (Emailed: 5/21/2013)
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30 year-old male presents with right wrist pain after falling off his bicycle. What's the diagnosis?

Scapholunate dislocation

Scapholunate Dislocation (a.k.a. “Terry Thomas” or “David Letterman” sign)

Increased distance between the scaphoid and lunate bones on AP wrist X-ray; the distance between the two bones should normally be less than 2mm.
A widened scapholunate distance suggests ligamentous injury or tear (green arrow below).
The widened distance resembles the famous dental diastema (i.e., tooth gap) of Terry Thomas (British comedian) and David Letterman

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