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