Updated: 4/15/2020

Pediatric Ankle Trauma Radiographic Evaluation

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 Normal Anatomy
 Ossification

 

  • Order of ossification of tibia: central to medial to lateral
 Osteology & Attachments
  • Anterior view
  • Anterolateral view
  • Posterior view
  • Medial view
  • Lateral view
  • Superior view
 Radiographic Views
 AP view
  • Positioning
    • patient 
      • supine
      • knee extended + foot dorsiflexed
    • beam
      • aim at mid-tibiotalar joint
  • Critique
    • lateral malleolus closer to plate
    • open medial joint space + tibiotalar joint
    • closed lateral joint space
    • slight superimposition of talus + fibula
      • increased by ER + decreased by IR
 Mortise view
  • Positioning
    • patient
      • supine
      • knee extended + leg IR 15° + foot dorsiflexed
    • beam
      • aim at mid-tibiotalar joint
  • Critique
    • slight superimposition of fibula + tibia
    • open lateral joint space + tibiotalar joint
    • closed medial joint space
    • no visualization of sinus tarsi
      • too much IR if visible
  Lateral view 
  • Positioning
    • patient
      • supine
      • knee extended + leg/ankle ER 90° + foot dorsiflexed
    • beam
      • aim at medial malleolus
  • Critique
    • superimposition of medial + lateral malleoli
    • superimposition of talar domes
      • superoinferior plane = lateral dome moves more proximal if proximal tibia higher than distal tibia
      • AP plane = lateral dome moves posterior if too much ER
    • superimposition of fibula + tibia
      • fibula on posterior half of tibia but not superimposing posterior malleolus
      • fibula moves anteriorly if too much IR
    • open tibiotalar joint
    • visualization of pre-talar fat pad
      • requires foot dorsiflexion
 Oblique view
  • Positioning
    • patient
      • supine
      • knee extended + foot IR/ER 45°
    • beam
      • aim at mid-tibiotalar joint
  • Critique
    • medial/IR
      • open lateral mortise + tibiotalar joint
        • mortise closes with too much IR
      • closed medial mortise
      • slight superimposition of fibula + tibia
      • no superimposition of talus + fibula
      • no visualization of sinus tarsi 
        • too much IR if visible
    • lateral/ER
      • superimposition of fibula + tibia
 Stress view 
  • Positioning
    • patient
      • manual stress = supine + knee extended + ankle inverted/everted
      • gravity stress = supine + hip ER + knee flexed + ankle placed on bump
    • beam
      • aim at tibiotalar joint
  • Uses
    • joint stability = < 5° difference between ipsilateral + contralateral ankles
    • ER stress = evaluates syndesmotic/deep deltoid ligament injury
    • IR stress = evaluates LCL injury
 Normal Radiographic Findings

 


VIEW
MEASUREMENT TECHNIQUE
NORMAL FINDINGS
 
Tib-fib clear space
AP/mortise measure 1 cm above joint < 6mm
Tib-fib overlap
AP/mortise measure at maximum overlap

> 6mm or 42% fibular width on AP view; > 1mm on mortise view

Talar tilt
AP/mortise difference in width of superior clear space
< 2mm or < 2° on AP view, < 2mm or 0° on mortise view
Talocrural angle
mortise angle between intermalleolar line + line perpendicular to tibial articular surface < 83° ± 4°
Medial clear space
mortise distance between lateral medial malleolus + medial talus ≤ 4mm
Shenton's line
mortise line along lateral plafond
continuous
Dime test  mortise line along lateral talus + lateral malleolus
continuous
Hawkin's sign 
mortise subchondral radiolucent band in talar dome seen 6-8 wks post-injury, results from revascularization of talar body present (absence indicates AVN)
Heel-pad thickness
lateral
 
shortest distance between plantar calcaneus + skin  23mm in females, 25mm in males (increased in acromegaly) 
Achilles tendon thickness
lateral measure 1-2cm above calcaneus 4-8mm

 

 Radiographic Clinical Pearls 
 Ottawa Ankle Rules
  • XRs are indicated if any of the following criteria are met
    • TTP at medial malleolus
    • TTP at lateral malleolus
    • inability to bear weight, i.e. ambulate >4 steps
 Ankle Effusion
  • Malleolar sign = asymmetrical thickness of soft tissue overlying medial + lateral malleolus
  • Effusion teardrop sign = occurs at anterior/posterior juxta-capsular region
  • Kager’s fat pad = located between FHL + achilles tendons
 Pediatric Ankle Fracture  
  • Classification = Dias-Tachdijian  
    • supination-inversion
    • pronation-eversion ER
    • supination-plantarflexion
    • supination-ER
  • Recommended views
    • AP
    • lateral
    • mortise
    • full-length tibia, or proximal tibia, to rule out Maisonneuve-type fracture
  • Treatment criteria
    • nonoperative treatment acceptable if < 2mm displacement + extra-articular
    • CRPP vs. ORIF if
      • > 2mm displacement
      • intra-articular
      • irreducible reduction by closed means
 Tillaux Fracture  
  • Recommended views
    • AP
    • lateral
    • mortise
  • Findings 
    • SH III avulsion of AITFL off anterolateral tibia
  • Treatment criteria
    • nonoperative treatment acceptable if < 2mm displacement
    • ORIF if > 2mm displacement
 Triplane Fracture  
  • Recommended views
    • AP
    • lateral
    • mortise
  • Findings
    • consists of 3 parts
      • anterolateral quadrant of distal tibial epiphysis
      • medial and posterior portions of epiphysis with posterior metaphyseal spike
      • tibial metaphysis
    • AP radiograph shows Salter-Harris III  
    • lateral radiograph shows Salter-Harris II 
  • Treatment criteria
    • nonoperative treatment acceptable if < 2mm displacement
    • CRPP vs. ORIF if > 2mm displacement
 

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