Complete dislocations of the lunate
In complete dislocations of the lunate, the displacement is usually in a palmar direction. The greater force required to produce this injury is responsible for massive disruption of both the dorsal and palmar ligaments.
Disruption of the dorsal radiolunotriquetral ligament complex
There is also a disruption of the dorsal radiolunotriquetral ligament complex.
“Spilled teacup” sign
The capitate displaces proximally towards the distal radial articular surface. A lateral radiograph shows the “spilled teacup” configuration of the lunate.
On the AP view, the displaced lunate has a triangular profile, rather than its normal quadrilateral image.