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https://upload.orthobullets.com/topic/6034/images/xray.jpg
https://upload.orthobullets.com/topic/6034/images/mri.jpg
https://upload.orthobullets.com/topic/6034/images/bone scan.jpg
https://upload.orthobullets.com/topic/6034/images/snuffbox.jpg
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Introduction
  • Scaphoid is most frequently fractured carpal bone
  • Epidemiology
    • incidence
      • accounts for up to 15% of acute wrist injuries
    • location
      • incidence of fracture by location
        • waist -65%
        • proximal third - 25%
        • distal third - 10%
          • distal pole is most common location in kids due to ossification sequence
  • Pathoanatomy
    • most common mechanism of injury is axial load across hyper-extended and radially deviated wrist 
      • common in contact sports
    • transverse fracture patterns are considered more stable than vertical or oblique oriented fractures
  • Associated conditions
    • SNAC (Scaphoid Nonunion Advanced Collapse) 
  • Prognosis
    • incidence of AVN with fracture location
      • proximal 5th AVN rate of 100%
      • proximal 3rd AVN rate of 33%
Anatomy
  • Articular surface
    • > 75% of scaphoid bone is covered by articular cartilage
  • Blood supply 
    • major blood supply is dorsal carpal branch (branch of the radial artery) 
      • enters scaphoid in a nonarticular ridge on the dorsal surface and supplies proximal 80% of scaphoid via retrograde blood flow
    • minor blood supply from superficial palmar arch (branch of volar radial artery
      • enters distal tubercle and supplies distal 20% of scaphoid
  • Motion
    • both intrinsic and extrinsic ligaments attach and surround the scaphoid 
    • the scaphoid flexes with wrist flexion and radial deviation and it extends during wrist extension and ulnar deviation (same as proximal row)
  • Also see Wrist Ligaments and Biomechanics for more detail
Presentation
  • Physical exam
    • anatomic snuffbox tenderness dorsally 
    • scaphoid tubercle tenderness volarly 
    • pain with resisted pronation
Imaging
  • Radiographs
    • recommended views
      • AP and lateral 
      • scaphoid view 
        • 30 degree wrist extension, 20 degree ulnar deviation 
      • 45° pronation view
    • findings
      • if radiographs are negative and there is a high clinical suspicion 
        • should repeat radiographs in 14-21 days
  • Bone scan 
    • effective to diagnose occult fractures at 72 hours 
      • specificity of 98%, and sensitivity of 100%, PPV 85% to 93% when done at 72 hours
  • MRI 
    • indications
      • most sensitive for diagnosis occult fractures < 24 hours 
      • immediate identification of fractures / ligamentous injuries 
      • assessment of vascular status of bone (vascularity of proximal pole)
        • proximal pole AVN best determined on T1 sequences
  • CT scan with 1mm cuts 
    • less effective than bone scan and MRI to diagnose occult fracture
    • can be used to evaluate location of fracture, size of fragments, extent of collapse, and progression of nonunion or union after surgery  
Treatment
  • Nonoperative
    • thumb spica cast immobilization
      • indications
        • stable nondisplaced fracture (majority of fractures)
        • if patient has normal xrays but there is a high level of suspicion can immobilize in thumb spica and reevaluate in 12 to 21 days
      • technique
        • start immobilization early (nonunion rates increase with delayed immobilization of > 4 weeks after injury)
        • long arm spica vs short arm casting is controversial 
          • with no consensus
        • duration of casting depends on location of fracture
          • distal-waist for 3 months
          • mid-waist for 4 months
          • proximal third for 5 months
          • athletes should not return to play until imaging shows a healed fracture
        • may opt to augment with pulsed electromagnetic field (studies show beneficial in delayed union)
      • outcomes
        • scaphoid fractures with <1mm displacement have union rate of 90%
  • Operative
    • ORIF vs percutaneous screw fixation  
      • indications
        • in unstable fractures as shown by
          • proximal pole fractures 
          • displacement > 1 mm
          • 15° scaphoid humpback deformity
          • radiolunate angle > 15° (DISI)
          • intrascaphoid angle of > 35°
          • scaphoid fractures associated with perilunate dislocation
          • comminuted fractures
          • unstable vertical or oblique fractures
        • in non-displaced waist fractures
          • to allow decreased time to union, faster return to work/sport, similar total costs compared to casting
      • outcomes
        • union rates of 90-95% with operative treatment of scaphoid fractures
          • CT scan is helpful for evaluation of union
Technique
  • ORIF vs percutaneous screw fixation
    • approach
      • dorsal approach
        • indicated in proximal pole fractures 
        • care must be taken to preserve the blood supply when entering the dorsal ridge by limiting exposure to the proximal half of the scaphoid
        • percutaneous has higher risk of unrecognized screw penetration of subchondral bone 
      • volar approach 
        • indicated in waist and distal pole fractures and fractures with humpback flexion deformities
        • allows exposure of the entire scaphoid
        • uses the interval between the FCR and the radial artery
      • arthroscopic assisted approach
        • has also been described
    • fixation
      • rigidity is optimized by long screw placed down the central axis of the scaphoid 
    • radial styloidectomy
      • should be performed if there is evidence of impaction osteoarthritis between radial styloid and scaphoid
Complications
  • Scaphoid Nonunion 
    • treatment
      • inlay (Russe) bone graft
        • indications
          • if minimal deformity and there is no adjacent carpal collapse or excessive flexion deformity (humpback scaphoid) 
        • outcomes
          • 92% union rate
      • interposition (Fisk) bone graft
        • indications
          • if there is adjacent carpal collapse and excessive flexion deformity (humpback scaphoid)
        • technique
          • an opening wedge graft that is designed to restore scaphoid length and angulation
        • outcomes
          • results show 72-95% union rates
      • vascular bone graft from radius
        • indications
          • gaining popularity and a good option for proximal pole fractures with osteonecrosis confirmed by MRI
        • technique
          • 1-2 intercompartmental supraretinacular artery (branch of radial artery) is harvested  to provide vascularized graft from dorsal aspect of distal radius 
      • vascular bone graft from medial femoral condyle  
        • corticoperiosteal flap that provides highly osteogenic periosteum 
        • indications 
          • proximal pole fractures with osteonecrosis 
          • lack of pancarpal arthritis and collapse
        • technique 
          • utilize the descending genicular artery pedicle (from the superficial femoral artery)  
          • if DGA is too small, use superomedial genicular artery (from popliteal artery)
          • identify and protect MCL (distal to flap)
    • SNAC wrist (scaphoid nonunion advanced collapse) 
 

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