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Casting of Scaphoid Fractures

(See also: Work Up for Scaphoid Frx)

Discussion

  • w/ proper casting nearly 100% of tubercle & distal third frxs will heal;
  • in addition to healing considerations, the surgeon should note the position of healing (malunion);
  • approximately 80-90% of scaphoid frx at the waist will heal, but only 60-70% of proximal pole frxs will heal;
    • even when healing does occur, there will is a relatively high incidence of malposition & late collapse;
  • healing by location:

Casting Technique

  • non diagnostic radiograph (w/ positive snuff box tenderness);
    • if initial x-rays are negative, but suspicion is high, cast is applied in radial deviation & 10 deg of flexion w/ immobilization of thumb;
    • consider position of neurtral flexion / extension & slight ulnar deviation;
    • Weber notes that neutral flexion & slight radial deviation allows maximum opposition of frx frags;
  • non-displaced fractures
    • cast includes the proximal phalanx of thumb w/ wrist in 10 deg flexion and radial deviation to provide compression & radial deviation of the fragments;
      • volar upward pressure is applied on the distal pole of the scaphoid
      • dorsal downward pressure is applied on the capitate;
        • displacement of the capitate volarly rotates the lunate and proximal pole into flexion and closes the dorsal scaphoid gap;
    • most surgeons leave the IP joint free;
    • tubercle frxs are suitable for short arm cast, while pts w/ w/ proximal pole fractures are candidates for a long arm cast;

Post Injury Care

  • long thumb-spica cast is used for six weeks, followed by short thumb- spica cast until clinical and radiographic signs of union are seen;
  • immobilization for 16 weeks to 6 months is sometimes required;
  • undisplaced fractures unite in 8 to 12 weeks
  • consider changing the cast every 10-14 days for the first 6 weeks so that it remains firm around forearm muscles and the wrist;
  • many surgeons will cast for an additional 4-6 weeks once trabeculation is seen crossing the frx site (on radiographs), since the same frx seen on CT scanning may demonstrate a persistent frx gap;
  • if x-rays fail to clearly demonstrate trabeculae crossing site of frx, CT scan along axis of carpal scaphoid is performed;