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Terry Thomas sign

Dr Frank Gaillard and Dr Andrew Dixon et al.

The Terry Thomas sign refers to an increase in the scapholunate space on an AP radiograph of the wrist (or coronal CT). The increased distance indicates scapholunate dissociation (rotary subluxation of the scaphoid) due to ligamentous injury. There is no consensus as to what measurement constitutes widening but a cut-off of somewhere around 3 or 4mm is probably reasonable.

The sign is named after well-known British comic Terry Thomas (1911 - 1990) who had frontal dental diastema (a large gap between his two front teeth) ¹. It may also be known as the David Letterman sign for the same reason.