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:
  • times to union increasing for more proximal fractures;
  • distal third frx heal in approx 6-8 weeks;
  • middle third frx heal in 8-12 weeks;
  • proximal third frx heal in 12-23 weeks;

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;
  • this allows assessment of possible scaphoid nonunion

• Comparison of short and long thumb-spica casts for non-displaced fractures of the carpal scaphoid
• Clinical fracture of the carpal scaphoid--supportive bandage or plaster cast immobilization.
• Early mobilisation of Colles' fractures. A prospective trial.
• Consequences of late immobilization of scaphoid fractures.
• Nonoperative Compared with Operative Treatment of Acute Scaphoid Fractures
• Clinical and radiological outcome of cast immobilisation versus surgical treatment of acute scaphoid fractures at a mean follow-up of 93 months
• Management of displaced fractures of the waist of the scaphoid: meta-analyses of comparative studies.