Scaphoid fracture

The scaphoid bone is the most commonly fractured carpal bone. Fractures are most often localized in the middle third of the scaphoid bone. Generally, scaphoid bone fractures result from indirect trauma when an individual falls onto the outstretched hand with a hyperextended and radially deviated wrist. Pain when applying pressure to the anatomical snuffbox is highly suggestive of a scaphoid bone fracture. X-ray is the initial test of choice for diagnosis. Computer tomography and magnetic resonance imaging may be indicated, if x-ray findings are negative but clinical suspicion is high. Treatment can be conservative (e.g, wrist immobilization) or in certain cases surgical (e.g., proximal pole fracture). Complications include nonunion and avascular necrosis.

• Most common carpal bone fracture (50–80%) ^[1]
• Peak incidence: 15–19 years ^[2]

Epidemiological data refers to the US, unless otherwise specified.

• According to the localization of the fracture ^[3]
  • Proximal third (proximal pole): ∼ 10%
  • Middle third (waist): ∼ 70%
  • Distal third (distal pole): ∼ 20%
    • Distal articular surface
    • Distal tubercle

• History of falling onto the outstretched hand; with a hyperextended and radially deviated wrist ^[4]
• Pain when applying pressure to the anatomical snuffbox and scaphoid tubercle (a palpable bony prominence on the inferior lateral edge of the scaphoid bone)
• Minimal reduction in the range of motion (except in dislocated fractures)
• Decreased grip strength
• Painful pinching and grasping
• Pain can be induced through axial compression along the first metacarpal (scaphoid compression test). ^[4]

When pain occurs in the anatomical snuffbox after trauma, the injury should be treated as a scaphoid fracture until proven otherwise.

• Best initial test: x-ray of the wrist in a posteroanterior, lateral, 45° oblique, and possibly scaphoid view (a x-ray view with ulnar deviation of the wrist and full pronation of the forearm to eliminate overlapping shadows of the radius)
  • ∼ 25% of scaphoid bone fractures are initially undetectable on x-ray. ^[5]
• If initial x-ray is negative, one of the following:
  • If the patient is not willing to immobilize the wrist: MRI of the wrist ^[6]
  • If the patient is willing to immobilize the wrist: cast the wrist and repeat an x-ray in 10–14 days
• If repeat x-ray is normal but continued clinical suspicion of scaphoid fracture: MRI of the wrist

Scaphoid fractures are often undetectable on the initial x-ray.

Lunate dislocation ^[7][8]

• Definition: disruption of perilunate ligaments and radiocarpal ligament with displacement of the lunate bone (usually volarly) while the rest of the carpal bones remain in a normal anatomic position
• Etiology: high-energy trauma with dorsal extension and ulnar deviation of the wrist
• Clinical features: : wrist swelling, pain, and signs of median nerve injury (e.g., acute carpal tunnel syndrome) ^[9]
• X-ray: The lateral radiograph shows a loss of colinearity of radius, lunate, and capitate.
• Treatment: emergent closed reduction and immobilization followed by open reduction and internal fixation

Transscaphoid perilunate dislocation

• Definition: dorsal dislocation of the wrist around the fixated, unmoved lunate bone; commonly associated with a fractured scaphoid bone (transcaphoid perilunate fracture-dislocation) ^[10]
• Etiology: fall onto a hyperextended wrist, deviated toward the ulna
• Clinical features: usually non-specific (pain in the wrist, swelling, restricted movement); possibly signs of median nerve injury ^[11]
• X-ray: most commonly, metacarpal bones displaced dorsally to the lunate bone in lateral view ^[12]
• Treatment: always surgical ^[5]
  • Closed reduction with cast immobilization
  • Open reduction and internal fixation
  • Scaphoid osteosynthesis

The differential diagnoses listed here are not exhaustive.

• Pain management: over-the-counter analgesics and strengthening exercises
• Nondisplaced fractures or displaced fractures < 1 mm: wrist immobilization via thumb spica cast: for a minimum of 6–8 weeks with x-ray re-evaluation in 2 weeks ^[13][14]
  • Distal scaphoid fractures: short arm thumb spica cast for 4–6 weeks
  • Waist or proximal scaphoid fracture: long or short arm thumb spica cast
• Surgical treatment
  • Usually internal fixation ^[13]
  • Indications are complicated cases that include: ^[14][15]
    • Displaced fractures > 1 mm
    • Open fractures
    • Signs of neurovascular compromise and/or osteonecrosis
    • Proximal pole fractures
    • Nondisplaced fractures upon patient's wish for early remobilization
    • Late presentation (> 3 weeks of fracture onset)
    • Instability of carpal bones
    • Rupture of the scapholunate ligament

• Avascular necrosis (especially in proximal fractures that disrupt blood flow from branches of the radial artery) of the scaphoid bone in up to 50% of cases ^[16]
• Nonunion (especially in proximal fractures) in approx. 10% ^[17]
• Delayed union of fracture (more common in smokers)
• Instability among carpal joints
• Post-traumatic arthritis

Fractures in the distal third tend to heal better because of the retrograde blood supply reaching the bone from the distal pole.

We list the most important complications. The selection is not exhaustive.