Age / Sex : 20 / M

Chief complaint : Right wrist pain after falling off a horse.

What is your diagnosis?

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

Courtesy : Yusuhn Kang, Seoul National University Bundang Hospital

Discussion

Answer: Trans-scaphoid perilunate (fracture) dislocation.

Findings:

Wrist PA radiograph

- Disruption of the 1^st and 2^nd carpal arcs of Gilula

- Fracture of the scaphoid bone at waist  

Proximal pole fragment maintains articulation with lunate.

Distal pole fragment maintains articulation with the distal carpal row.

Wrist lateral radiograph

Capitolunate joint disruptued with capitate dislocated dorsal to the lunate

Radiolunate articulation preserved

Differential Diagnosis: none.

Discussion:

Trans-scaphoid perilunate fracture-dislocation.

- Relatively uncommon but potentially serious wrist injury that is easily missed.

- Mainly seen in youths due to high energy trauma

(fall from a height onto an outstretched hand with wrist in hyperextended and ulnar deviated position)

Mayfield classification of carpal instability

• stage I: scapholunate dissociation

-  the scapholunate ligament is disrupted resulting in increased scapholunate interval.

2)  stage II: perilunate dislocation

- lunate normally aligned with the distal radius

the remaining carpal bones are dislocated (usually dorsally)

- the capitolunate joint disrupted, and the lunate projects through the space of Poirier

- 60% associated with scaphoid fractures(Trans-scaphoid perilunate dislocation)

3) stage III: midcarpal dislocation

- lunotriquetral interosseous ligament disruption or triquetral fracture

- both capitate and lunate do not align with the distal radius

4) stage IV: lunate dislocation

- dorsal radiolunate ligament injury

- dislocation of the lunate in a palmar direction

References:

1. Kloss BT, Patierno SR, Sullivan AM. Transscaphoid perilunate dislocation. Int J Emerg Med. 2010 Dec; 3(4): 501–502.


2. Mayfield JK, Johnson RP, Kilcoyne RK. Carpal dislocations: pathomechanics and progressive perilunar instability. J Hand Surg Am. 1980;5 (3): 226-41


3. Scalcione LR, Gimber LH, Ho AM et-al. Spectrum of carpal dislocations and fracture-dislocations: imaging and management. AJR Am J Roentgenol. 2014;203 (3): 541-50. doi:10.2214/AJR.13.11680