183ms

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Average 3.4 of 7 Ratings

Images
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https://devupload.orthobullets.com/topic/422868/images/scaphoidview.jpg
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  • Summary
    • Scaphoid Fracture Nonunion occur in 5-25% of scaphoid fractures following treatment, and are more common in older patients, smokers, and when there is a delay in the initial treatment of the fracture.  
    • Diagnosis is made with a combination of radiographs and a CT scan.  MRI studies may be used to assess for avascular necrosis.
    • Treatment is generally open reduction and internal fixation (ORIF) with bone grafting.
  • Epidemiology
    • Incidence
      • 5-10% following immobilization
      • some studies showing nearly 25% following surgical fixation
    • Demographics
      • parallels that of scaphoid fractures
      • 2 :1 male : female
      • most common in third decade of life
    • Risk factors
      • proximal pole fracture
      • vertical oblique fracture pattern
      • displacement >1mm
      • advancing age
      • nicotine use
  • Etiology
    • Pathophysiology
      • pathoantomy
        • lack of stability and/or biology leading to nonunion at fracture site
    • Associated conditions
      • osteonecrosis
      • SNAC (Scaphoid Nonunion Advanced Collapse)
  • Anatomy
    • Osteology
      • complex 3-dimensional structure described as resembling a boat or twisted peanut
      • oriented obliquely from extremity's long axis (implications for advanced imaging techniques)
      • largest bone in proximal carpal row
      • > 75% of scaphoid bone is covered by articular cartilage
      • articulates with radius, lunate, trapezium, trapezoid, and capitate
    • 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
      • creates vascular watershed and poor fracture healing environment
    • Biomechanics
      • link between proximal and distal carpal row
      • both intrinsic and extrinsic ligaments attach and surround the scaphoid
      • the scaphoid flexes with wrist flexion and radial deviation and extends during wrist extension and ulnar deviation (same as proximal row)
    • See Wrist Ligaments and Biomechanics for more detail
  • Classification
    • Generally divided into stable or unstable nonunion
      • stable
        • maintenance of length and overall alignment with fibrous union
      • unstable
        • loss of length or alignment with signs of carpal instability or degenerative chondral changes
  • Presentation
    • History
      • careful history to detail chronology of injury and treatment
      • may describe remote traumatic event
      • obtain previous operative reports and imaging studies if applicable
    • Symptoms
      • common symptoms
        • some patients will deny any significant symptoms
        • wrist pain
          • worsened with motion
        • difficulty with grip
    • Physical exam
      • inspection
        • variable degree of swelling
        • tenderness near fracture site
        • note location of previous incision(s)
      • motion
        • document flexion-extension and pronation-supination
          • variable degree of motion loss may be attributed to post-immobilization stiffness or mechanical derangement
  • Imaging
    • Radiographs
      • recommended views
        • neutral rotation PA and lateral, semi-pronated (45°) oblique view
        • scaphoid view
      • findings
        • cysts, sclerosis, bone resorption at fracture site, hardware loosening or failure
        • carpal instability
        • humpback deformity
        • SNAC arthritic changes
    • CT
      • indications
        • best modality to evaluate nonunion and for surgical planning
        • suspicion of SNAC arthritic changes
      • views
        • CT should be oriented in plane of scaphoid with 1mm cuts
        • most protocols can reduce metal artifact in post-surgical setting
      • findings
        • provides better detail of fracture pattern orientation, displacement, residual fracture gap, and angulation
        • bony resorption at fracture site
        • may show technical errors from previous surgery
        • evidence of SNAC
          • scaphoid, radial styloid, capitate and/or lunate subchondral cyst formation
    • MRI
      • indications
        • concern for osteonecrosis
      • sensitivity and specificity
        • inconsistent and questionable utility
        • gadolinium enhancement may improve quality
  • Differential
    • SNAC wrist 
  • Diagnosis
    • Clinical and radiographic
      • diagnosis confirmed by history, physical exam, radiographs, and CT
        • MRI needed to assess for AVN
  • Treatment
    • Nonoperative
      • cast immobilization
        • indications
          • lack of prior appropriate immobilization duration
            • may immobilize up to 6 months following surgery
          • refusal of surgery
        • contraindications
          • technical error with improper screw placement, implant failure, distraction at fracture site with loss of reduction
        • outcomes
          • 69% of surgically stabilized fractures without technical error or fracture displacement achieve union by 3 months with cast and addition of pulsed electromagnetic stimulation
    • Operative
      • Open reduction internal fixation with bone grafting
        • indications
          • lack of fracture union by 6 months
            • technical error with improper implant placement, implant failure, distraction at fracture site with loss of reduction
            • nonunion without osteonecrosis or SNAC
        • outcomes
          • 92% union rate
          • likely best outcome when nonunion due to simple technical error during index procedure
      • bone graft options
        • overview
          • bone graft substitutes:
            • PRP, BMP
          • non vascularised graft
            • interposition (Fisk)
            • inlay (Russe)
          • vascularised graft
            • local (pedicled): multiple techniques from distal radius
            • free (requires anastomosis): medial femoral condyle, medial trochlea, iliac crest
        • bone morphogenic protein (BMP) and platelet-derived plasma (PRP)
          • indications
            • nonunion without SNAC
            • used as adjunct to ORIF, avoids technical challenges and resource utilization of free flaps
          • outcomes
            • case series showing high success rate
        • inlay (Russe) non-vascularized corticocancellous bone graft
          • indications
            • no adjacent carpal collapse or excessive flexion deformity (humpback scaphoid)
            • volar approach
          • outcomes
            • 92% union rate
        • interposition (Fisk) non-vascularized corticocancellous bone graft
          • indications
            • adjacent carpal collapse and excessive flexion deformity (humpback scaphoid)
            • volar approach
          • outcomes
            • 72-95% union rates
        • Vascularized local corticocancellous bone graft
          • multiple techniques (Mathoulin, Zaidemberg, Sotrereanos etc)
          • indications
            • waist fractures with proximal pole osteonecrosis
            • lack of intraoperative punctate bleeding at fracture
            • lack of pancarpal arthritis
          • outcomes
            • 82% good to excellent outcomes
        • Free vascularized corticocancellous bone graft from medial femoral condyle (MFC) 
          • corticoperiosteal flap that provides highly osteogenic periosteum
          • indications
            • scaphoid waist fracture non-unions with proximal pole osteonecrosis
            • lack of intraoperative punctate bleeding at fracture
            • lack of pancarpal arthritis or collapse
          • outcomes
            • one study showing 100% union achieved by 13 weeks
        • Free vascularized osteochondral graft from medial femoral trochlea (MFT)
          • osteochondral graft
          • indications
            • scaphoid waist fracture non-unions with proximal pole osteonecrosis and loss of cartilage
            • lack of intraoperative punctate bleeding at fracture
            • lack of pancarpal arthritis or collapse
          • outcomes
            • studies reporting over 90% union rate
        • Free vascularized corticocancellous bone graft from iliac crest
          • indications
            • scaphoid waist fracture non-unions with proximal pole osteonecrosis
            • lack of intraoperative punctate bleeding at fracture
            • lack of pancarpal arthritis or collapse
          • outcomes
            • 76% union rate
  • Techniques
    • Cast immobilization
      • technique
        • long- or short-arm cast
        • pulsed electromagnetic field stimulation may be added
        • serial radiographs to confirm maintenance of fracture alignment and apposition
    • Open reduction internal fixation
      • approach
        • volar or dorsal approach, dictated by previous incision and implant
        • plate is applied through volar approach
      • technique
        • fracture site curetted to bleeding surface
        • cancellous autograft or allograft bone chips may be added to fracture site if desired
        • bone morphogenic protein (BMP) or platelet-derived protein (PRP) may also be added to add osteoinductivity
        • choice of k-wire plate, screw, or staple osteosynthesis
        • headless compression screw placed distal to proximal in the volar approach, or proximal to distal for the dorsal approach
        • plate applied to provide volar buttress
        • k-wire has advantage of removal to avoid symptomatic hardware
      • Bone Grafting techniques
        • Inlay (Russe) bone graft
          • nonvascularized corticocancellous bone graft
          • approach
            • volar approach using interval between the FCR and the radial artery
          • technique
            • various modifications of originally described procedure
            • corticocancellous bone graft harvested from distal radius or iliac crest
            • graft placed within scaphoid acting as cortical strut to restore length, alignment, and angulation
            • headless screw placed across fracture sitebleeding from fracture intra-operatively highly predictive of vascularized proximal pole fragment
        • Interposition (Fisk) bone graft
          • nonvascularized corticocancellous bone graft
          • approach
            • volar approach as above
          • technique
            • corticocancellous distal radius (original technique) or iliac crest (Fernandez modification) bone graft used as anterior wedge to restore length, alignment, and angulation
            • dimensions of graft to be harvested are calculated pre-operatively
        • Vascularized corticocancellous bone graft from dorsal distal radius (Zaidemberg 1,2-ICSRA)
          • approach
            • dorsal approach between 1st and 2nd dorsal extensor compartments
            • artery overlying extensor retinaculum
          • technique
            • 1-2 intercompartmental supraretinacular artery (branch of radial artery) is harvested to provide vascularized graft from dorsal aspect of distal radius
            • longitudinal capsulotomy made overlying scaphoid nonunion
            • bone graft placement depends on nonunion location and deformity correction needed
        • Vascularized radial corticocancellous bone graft using volar carpal artery (Mathoulin)
          • approach
            • volar approach as above
            • artery found distal to the pronator quadratus aponeurosis and radial periosteum
          • technique
            • corticocancellous bone graft and pedicle raised with rim of fascia
            • graft placed as wedge to correct fracture collapse or humpback deformity if present
        • Vascularized radial corticocancellous bone graft using dorsal capsular pedicle (Sotereanos)
          • approach
            • incision centered over the 4th extensor compartment just ulnar to Lister's tubercle
          • technique
            • pedicle uses artery of fourth dorsal compartment located ulnar and distal to Lister's tubercle
            • corticocancellous bone graft harvested with dorsal wrist capsule
            • placed into fracture site in an inlay fashion
        • Free vascularized bone graft from medial femoral condyle (MFC)
          • approach
            • longitudinal incision along posterior border of vastus medialis
            • vastus medialis lifted anteriorly
            • descending genicular vessels identified proximally near adductor hiatus and dissected distally to periosteum overlying condyle
            • identify and protect MCL (distal to flap)
          • technique
            • corticocancellous bone graft harvested from knee using either descending genicular artery, or superomedial genicular vessels if DGA too small
            • utilize the longitudinal branch of the descending genicular artery pedicle (from the superficial femoral artery)
            • bone graft placed volarly as wedge to restore length, alignment, and angulation
            • requires anastomosis
        • Free vascularized osteochondral graft from medial femoral trochlea (MFT)
          • approach
            • same as for free MFC graft
          • technique
            • periosteal branches from DGA identified at condylar flare
            • graft harvested and pedicle raised
            • avascular proximal pole resected and graft placed and fixated with headless screw, plate or K-wire
            • requires anastomosis
        • Free vascularized corticocancellous bone graft from iliac crest
          • approach
            • standard approach for iliac crest bone graft
          • technique
            • identify branch of deep circumflex iliac artery
            • raise corticocancellous graft preserving pedicle
            • place graft into fracture though either volar or dorsal approach
            • requires anastomosis
  • Complications
    • Osteonecrosis
      • more common with proximal fracture patterns
    • Graft failure and scaphoid nonunion advanced collapse
  • Prognosis
    • Natural history of disease in some cases
      • derangement of normal carpal mechanics
      • progressive and/or persistent wrist pain
      • cartilage loss
      • scaphoid nonunion with advanced collapse (SNAC)
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