Updated: 10/3/2020

Scaphoid Fracture Nonunion

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Introduction
  • Overview
    • Scaphoid fractures are prone to non-union because of retrograde blood supply, limited cancellous bone, limited soft tissue attachments, lack or periosteum, tension at the scaphoid waist, intra-articular nature, and often have a delayed diagnosis 
      • treatment involves achieving mechanical stability with perfused bone
  • 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
    • location
      • proximal pole fractures most common
    • risk factors
      •  vertical oblique fracture pattern, displacement >1mm, advancing age, nicotine use
  • Pathophysiology
    • pathoantomy
      • lack of stability and/or biology leading to nonunion at fracture site
  • Associated conditions
    • osteonecrosis 
    • SNAC (Scaphoid Nonunion Advanced Collapse) 
  • Prognosis
    • natural history of disease
      • derangement of normal carpal mechanics may lead to progressive and/or persistent wrist pain, cartilage loss, and scaphoid nonunion with advanced collapse (SNAC) with arthritic
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
  • Formal classifications exist but rarely used
    • Slade-Dodds classification system based on bone resorption exists
    • Herbert 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
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
    • general indications
      • lack of fracture union by 6 months  
      • technical error with improper implant placement, implant failure, distraction at fracture site with loss of reduction
    • surgical considerations
      • previous surgical technique and implants used, available bone stock, residual bony deformity, and vascularity
    • Fixation
      • Open reduction internal fixation 
        • indications
          • nonunion without osteonecrosis or SNAC 
        • outcomes
          • 92% union rate
          • likely best outcome when nonunion due to simple technical error during index procedure
    • Bone Grafting Procedures
      • 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
  • Fixation
    • 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 Procedures
    • 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 
 

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(OBQ07.127) A 20-year-old skateboarder fell 6 months ago and has had radial-sided wrist pain since. His radiograph upon presentation to your office is shown in figure A. What is the most appropriate treatment at this time? Tested Concept

QID: 788
FIGURES:
1

four corner fusion

2%

(62/3697)

2

long arm thumb spica cast

1%

(37/3697)

3

wrist arthroscopy to evaluate intercarpal ligaments

1%

(45/3697)

4

open reduction internal fixation with autologous bone graft

95%

(3523/3697)

5

wrist arthrodesis

0%

(10/3697)

L 1 C

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