Wrist Injury

Anatomy

  • The scaphoid is one of the carpal bones (Proximal row then distal row, both lateral-to-medial: Scaphoid Lunate Triquetrium Pisiform / Trapezium Trapezoid Capate Hamate)
  • Its blood supply is from distal to proximal, thus fractures can cause disruption of this supply and avascular necrosis

History

  • Often occurs due to a FOOSH (fall on outstretched hand), or a crush injury
  • Patient complains of wrist pain – usually radial, and worse with movement

Physical Exam

  • Inspection:
    • Swelling – may be found around the radial and posterior parts of the wrist
    • Erythema, Atrophy, Deformity, Skin changes
  • Palpation:
    • Tenderness:
      • Classically tenderness is within the anatomic snuff box (depression within the borders formed by EPB & EPL)
      • Tenderness when palpating the volar tubercle of the scaphoid (first bony prominence distal to the volar distal radius)
      • Radial sided tenderness on ulnar and radial deviation
      • Tenderness on supination against resistance
      • Tenderness on forced dorsiflexion
    • Effusion, Swelling, Temperature, Crepitus, Atrophy
  • ROM – may note decreased flexion and extension
  • Neurovascular exam (pulses, sensory, motor)
  • Assessment of joints above and below (elbow, fingers)
  • Special tests (from E-medicine)
    • Watson (scaphoid shift) test
      • Take the patient’s wrist (forearm pronated) into full ulnar deviation and extension. Press the patient’s thumb with other hand and then begin radial deviation and flexion of the patient’s hand.
      • If the scaphoid and lunate are unstable, the dorsal pole of the scaphoid subluxes over the dorsal rim of the radius and the patient complains of pain, indicating a positive test.
    • Scaphoid stress test
      • Hold the patient’s wrist with one hand so that thumb applies pressure over the patient’s distal scaphoid. The patient then attempts radial deviation of the wrist.
      • If excessive laxity is present, the scaphoid is forced dorsally out of the scaphoid fossa of the radius with a resulting audible clunk and pain, indicating a positive test.



 

Imaging

  • Xray Views:
    • Scaphoid view (AP w/ 30 deg supination & ulnar deviation)
    • Pronated oblique (for the STT joint)
    • Lateral view
    • PA of wrist w/ ulnar & radial deviation
  • May require imaging in 2 weeks (immobilization in cast) as fracture may not be evident until healing process begins
  • CT scan may be necessary to assess stability and union issues
  • Fracture locations
    • Tubercle
    • Distal pole
    • Waist
    • Proximal pole
  • Fracture orientation
    • Ttransverse
    • Oblique
    • Vertical

Management

  • Non-displaced (or radiographically negative, but high suspicion)
    • Cast immobilization (wrist in slight radial deviation and slight palmar or neutral flexion, includes proximal phalynx of thumb)
      • Long thumb-spica cast X six weeks
      • Short thumb-spica cast (until clinical and radiographic signs of union are seen)
    • Time to heal
      • Distal third 6-8 weeks
      • Middle third 8-12 weeks
      • Proximal third 12-23 weeks
  • Indications for surgical internal fixation:
    • Unstable fracture (as seen on imaging)
    • Displacment > 1 mm
    • Radiolunate angle > 15 degrees
    • Scapholunate > 60 degrees
  • Internal fixation
    • Herbert screw
    • Average time until back to work ~4weeks
    • Good rates of union

Complications

  • Union issues: delayed union (incomplete union after 4 months of cast immobilization), nonunion, malunion
  • Avascular necrosis (AVN) – osteonecrosis occurs in 15-30% of scaphoid fractures (most occurring within the proximal pole)

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