Frankel 1977 - The Terry-Thomas Sign

Summary

Rotational subluxation of the carpal navicular bone in the wrist is a rare and often overlooked injury.

The condition involves the proximal pole of the navicular rotating backwards and the distal pole rotating forwards, creating a gap between the navicular and lunate bones visible on x-ray.

The author proposes using the dental diastema (gap between the front teeth) of British comedian Terry-Thomas as a visual mnemonic to remember the radiographic appearance of navicular subluxation.

The gap between the navicular and lunate bones on x-ray resembles Terry-Thomas' dental diastema when he smiles. This is dubbed the "Terry-Thomas sign".

Recognition of this sign allows diagnosis of the injury. Treatment involves rotation and pinning of the navicular bone to close the gap.

Anthropomorphic similarities like the Terry-Thomas sign can serve as useful memory aids for recognizing challenging orthopedic conditions.