What's the Diagnosis?

A 21 yo F presents with L wrist pain after falling forward during a cross country race. On exam, she has swelling and tenderness over the distal radius. A L wrist xray is obtained. What's the diagnosis? (scroll down for answer)



Answer: Scapholunate dissociation (also note fracture of radial styloid process)

  • Injury involving disruption of the scapholunate ligament, resulting in separation between the scaphoid and lunate bones
  • Classic mechanism of injury is axial loading to a hyperextended wrist (FOOSH)
  • Most common injury causing carpal instability
  • AP radiograph demonstrates widening of the scapholunate space > 3mm ("Terry Thomas sign")
  • Associated distal radius fracture seen in up to 30% cases
  • ED treatment- thumb spica splint for immobilization, referral to orthopedics