The image shows a widened scapholunate joint space. Look at the other intercarpal joints for comparison. These joint spaces are usually 2 mm or less in width -- 4 mm or wider is usually considered abnormal, and betweeen 2 and 4 mm is a gray zone. This widened joint space was originally called the "Terry Thomas" sign, after the British character actor with a gap between his two front teeth. As radiology attendings grow older and radiology residents grow younger, recognition of this name becomes less and less frequent (sigh....). Referring instead to a "David Letterman" sign usually elicits signs of comprehension nowadays, but don't touch that dial....
This more detailed view of the wrist shows the lunatotriquetral joint and ligament nicely. The scapholunate joint and ligament should also look pretty much like this. However, in this patient, we can only see the tiny torn ends of the ligament. The torn fragments of ligament can be seen even better in the gradient echo image below. Rupture of this ligament can allow the scaphoid to sublux in a rotary fashion. When this happens, the scaphoid may appear somewhat foreshortened, since the X-ray beam is then parallel to the long axis of the scaphoid.
