Age / Sex : 64 / M

Chief complaint :  Left wrist pain

What is your impression?

Two weeks later, you can see the final diagonosis with a brief discussion of this case (Please submit only one answer).

Courtesy : Ik Yang, Kangnam Sacred Heart hospital, Hallym University

Discussion

Answer:  

Lunate dislocation

Findings:

1. Disrupted carpal arc 2 is indicative of displacement of the carpal bone


2. Triangular appearance of lunate on fronatal porjection

Normal three carpal arcs 

• Arc 1: connection line of proximal convexities, through scaphoid, lunate and triquetrum


• Arc 2: connection line of distal concave surface, through scaphoid, lunate and triquetrum


• Arc 3: connection line of proximal convexities, through capitate & hamate

: Disrupted carpal arcs are indicative of displacement of the carpal bones

Wrist lateral view well demonstrates anterior displacement of lunate.

 Pre- and post-operative radiographs

Pre-operative radiograph; Disrupted carpal arc 2 is indicative of displacement of the carpal bone

Post- operative radiograph well demonstrates normal alignment of arc 2.

Differential Diagnosis:

 Perilunate dislocation

Discussion:

Lunate and Perilunate dislocation; carpal dislocations decribed by extent of ligamentous injury (Mayfield)

Stage I  Isolated rotatory subluxation of scaphoid

Stage II  Dislocation or subluxation of capitate

Stage III  Perilunate dislocarion

Stage IV  Lunate dislocation

Lunate dislocation

• Most severe of carpal instabilities


• Most commonly associated with a trans-scaphoid fracture


• Involves all the intercarpal joints and disruption of most of the major carpal ligaments


• Produces volar dislocation and forward rotation of lunate 




• Concave distal surface of lunate comes to face anteriorly




• Capitate drops into space vacated by lunate 


• Capitate and all other carpal bones lie posterior to lunate on lateral radiograph


• Triangular appearance of lunate on frontal projection  

References:

근골격영상의학 강흥식, 홍성환, 강창호. 법문에듀케이션  2013 손과 손목 p597-604