Case in the Spotlight 18 - Answer and Discussion

Report


Normal alignment is noted at the distal radioulnar articulation. Appearances are suspicious for a fracture involving the proximal pole of the scaphoid bone. Additionally, there appears to be lunate dislocation. Remaining bones are unremarkable

A CT was performed. Report as below


There is an impacted fracture of the proximal pole of scaphoid with a few tiny fragments off the medial cortex of the proximal pole of scaphoid. There is complete lunate dislocation with the lunate rotated and volarly displaced.
The radiolunate alignment is completely disrupted. There is significant widening of the scapholunate and lunotriquetral interval. Also seen is a tiny cortical fragment coming off the distal radius dorsally.
 

 Perilunate answer 2

 

On the lateral view, the sequence  of adjacent C-shaped articular surfaces is disrupted and the axes of the radius' lunate' capitate, and third metacarpal are not collinear- With perilunate dislocation, the capitate  is dorsally dislocated  with respect to the lunate, while the lunate is  in its normal position  in the lunate
fossa  of the distal radius

 

Management

A backslab, and appropriate analgesia is required.
Neurovascular examination to be performed and documented.

D/w the orthopaedic registrar, and in general in the hospital setting there should always be another person on site who is able to review the films with you.

Lunate dislocation is an orthopaedic emergency and the management is theatre for reduction. Unlikely to be a Biers block in ED.

Dorsal perilunate dislocations and volar lunate dislocations are severe injuries, and both are prone to misinterpretation and being missed injuries

  • In perilunate dislocation, the the capitate is dislocated dorsal to the lunate
  • In lunate dislocation, the lunate is dislocated anteriorly and rotated, relative to the radius
  • Both of these injuries are associated with carpal fractures and median nerve injury

References


http://www.orthobullets.com/hand/6045/lunate-dislocation-perilunate-dissociation

http://radiopaedia.org/articles/perilunate-dislocation

These provide an excellent summary

It is probably worth considering what the top ten missed fractures are, and spend some time on them.
This is one of them. What might the top ten be?

Also the following reference looks at: scaphoid fracture, elbow and calcaneus.
http://eradiology.bidmc.harvard.edu/LearningLab/musculo/Sittler.pdf