Scaphoid Fracture

Snapshot

• A 27-year-old man falls from standing height and lands on his outstretched left hand. He complains of severe left wrist pain and immobility secondary to pain. On exam, he has tenderness over the anatomic snuffbox. A radiograph of his left wrist is shown and demonstrates a fracture of the proximal pole of the scaphoid.

Introduction

• Clinical definition
  • fracture of the scaphoid bone
• Epidemiology
  • incidence
    • most common carpal bone fracture
• Etiology
  • fall from standing height on an outstretched hand
  • high-energy trauma is less common
• Pathoanatomy
  • normal anatomy
    • the scaphoid is one of four bones in the proximal carpal row of the wrist
      • other three are the lunate, triquetrum, and pisiform 
    • articulations
      • radius proximally
      • lunate medially
      • trapezium, trapezoid, and capitate distally
    • anatomic subdivisions
      • proximal third
      • middle third (waist)
      • distal third
    • vascular supply
      • dorsal carpal branch of radial artery supplies proximal 80% of the scaphoid via retrograde flow
        • the proximal scaphoid is the most likely to undergo avascular necrosis (AVN) due to its tenuous retrograde blood supply 
      • superficial palmar branch of radial artery supplies distal 20% of the scaphoid
  • fracture location
    • 65% scaphoid waist
    • 25% proximal third 
    • 10% distal third
      • the distal third is the most common site for young children due to the ossification pattern
• Prognosis
  • favorable
    • stable non-displaced fracture
  • unfavorable
• unstable displaced fracture

Presentation

• Symptoms 
  • radial wrist pain
• Physical exam
  • anatomic snuffbox tenderness dorsally 
  • scaphoid tubercle tenderness volarly 
• pain with resisted pronation

Imaging

• Radiography 
  • indications
    • always indicated if the fracture is suspected
    • initial radiographs may be negative
      • if clinical suspicion is high, should repeat radiographs 2-3 weeks after the injury 
  • findings
    • fracture line through the scaphoid
• MRI 
  • indications
    • most sensitive imaging modality within first 24 hours
    • can be used if initial radiographs are negative
  • findings
    • best modality to demonstrate associated ligamentous injuries
• allows for assessment of the vascular integrity of proximal pole of scaphoid if AVN is suspected

Differential

• Distal radius fracture 
  • fracture will be evident on an AP and/or lateral radiograph of the wrist
  • more likely in older patients
• Wrist sprain
  • ligamentous injury in the absence of a fracture will be evident on MRI 
• Lunate dislocation 
  • can lead to symptoms of median nerve compression in the carpal tunnel 
• will be seen as disruption of Gilula lines on plain radiographs

Treatment

• Non-operative
  • thumb spica cast immobilization
    • indications
      • stable non-displaced fractures
      • normal radiographs but a high index of suspicion for occult fracture
• Operative
  • percutaneous pin fixation vs open reduction and internal fixation (ORIF)
    • indications
      • unstable fractures
      • proximal pole fractures
      • comminuted fractures
• vertical oblique fractures

Complications

• AVN  
  • most common in proximal injuries due to a retrograde blood supply
  • joint instability and worsening pain hours to days after initial scaphoid injury
• Non-union
  • scaphoid non-union advanced collapse (SNAC)
    • progressive wrist arthritis due to chronic scaphoid non-union