Lunate dislocation

Case contributed by Lucas Meira Sarlo


Automobile trauma.

Patient Data

Age: 35 years
Gender: Male
  • loss of Gilula arcs
  • proximal migration of capitate 
  • capitate not sitting within the distal articular 'cup' of the lunate
  • a line drawn through radius and lunate fails to intersect capitate 
  • lunate is seen displaced and angulated volar (as opposed to perilunate dislocation where it usually remains in articulation with distal radius)
  • piece of pie sign: although also seen in perilunate dislocation it may prove very helpful in initial identification of lunate related pathology
  • Terry-Thomas sign: increase in the scapholunate space on an AP radiograph of the wrist

Case Discussion

Lunate dislocation must be distinguished from perilunate dislocation. The main key to the diagnosis of lunate dislocation is the appearance of the teacup pouring between the lunate and radius, while in the perilunate dislocation it does not.

Case courtesy Dr. Thales A. Caricati.

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