A 46-Year-Old Woman with Wrist Pain After Hearing a ‘Snap’

Differential Diagnosis

• Distal radius fracture
• Ulnar styloid fracture
• Scaphoid fracture

Carpal instability dissociative injury

Diagnosis

Findings are concerning for scapholunate carpal instability dissociative injury (CID) suggestive of a full thickness tear.

Learnings/What to Look for

• The AP view reveals widening of the scapholunate interval
• The lateral view shows widening of scapholunate angle, normal lunocapitate angle, and slight dorsal rotation of lunate
  • Scapholunate angle widened (should be 30⁰–60⁰); this is due to slight dorsal angulation of the lunate

Pearls for Urgent Care Management and Considerations for Transfer

• Treatment of CID may be nonoperative or operative
  • Midcarpal instability can often be managed with immobilization and splinting
  • Surgery may be necessary with ulnar translation associated with styloid fractures, with midcarpal instability with late diagnosis that failed nonoperative management, and with distal radius malunion