An AP wrist plain film, a space is seen between the Scaphoid and the lunate , where ordinarily they are closely apposed.

This is abnormal which means that the scapholunate ligament is ruptured. This is diagnostic of a rotatory subluxation of the navicular.
This has been called the Terry Thomas sign after a famous British actor (1950s) who had a gap between his two front teeth !!

The Lancet, Volume 362, Issue 9400, Page 2026, 13 December 2003
Culture and medical terms: help or headache?
by : Saeed Rad , Karim Vessal , Farrokh Habibzadeh

Source: M.T. Niknejad (radRounds Radiology Network Member)