The frontal wrist x-ray shows a scaphoid fracture. There is crowding of the carpal bones as opposed to what should be a normal configuration with 1-2 mm distance between the carpal bones.

On the lateral view, the capitate along with the metacarpals are dislocated posteriorly with resultant perilunate dislocation.

The patient underwent operative management.

Perilunate dislocation:

• Common mechanism is fall on outstretched hand.
• Ligament disruption between the capitate & lunate allows the capitate to dislocate from the cup shaped distal lunate surface.
• On Ap view, the lunate, instead of showing a normal rhomboid shape with parallel upper and lower borders, appears triangular or pie shaped.
• On the lateral view, there is disruption of the normal cup & saucer anatomy between distal radius, lunate & capitate.

• Perilunate dislocation is commonly associated with a transscaphoid fracture.

Reference : Fundamentals of Diagnostic Radiology by Brant & Helms.