CT Wrist — DRUJ Instability (Dynamic Pronation/Supination)

Indications

• Suspected distal radioulnar joint (DRUJ) instability or subluxation
• Post-traumatic assessment (TFCC injury, distal radius/Galeazzi fracture aftermath)
• Pre/post-operative evaluation of DRUJ stabilization

Patient prep

• BOTH wrists scanned together — the asymptomatic side is the internal control
• Prone, both arms extended overhead, hands positioned symmetrically
• Place a radiopaque marker (BB) on the symptomatic side
• No contrast

Contrast

Technique

• Two (or three) acquisitions through the DRUJ: full PRONATION and full SUPINATION (± neutral), both wrists in each acquisition
• Identical FOV, centering and technique for every position so sides and positions are directly comparable
• Short axial coverage centered on the DRUJ/distal radius (a few cm) — dose per acquisition is tiny
• Thin 0.6-1 mm axial bone recons; measure ulnar head position with radioulnar line, epicenter or congruity methods, comparing sides in the same position

Series / Sequences

Key points

• Instability is positional — a neutral-only exam misses it; pronation and supination under load are the diagnostic positions
• Symmetric bilateral imaging is the trick: compare the symptomatic DRUJ to the contralateral side in the SAME rotation before calling subluxation (normal laxity varies widely)
• Apply a standard measurement (radioulnar line / epicenter / congruity method) and name it in the report
• Total dose is minimal — small anatomy, short coverage; don't let the multi-acquisition design scare anyone off

References