Updated: 5/7/2019

Triplane Fractures

Review Topic
https://upload.orthobullets.com/topic/4029/images/triplane ap_moved.jpg
https://upload.orthobullets.com/topic/4029/images/ossification pattern.jpg
  • Overview
    • triplane fractures are a traumatic ankle fracture seen in children 10-17 years of age characterized by a complex SH IV fracture pattern in multiple planes
      • treatment is closed reduction or surgical fixation depending on the degree of fracture displacement
  • Epidemiology
    • incidence
      • accounts for 5-15% of pediatric ankle fractures
    • demographics
      • more common in males
      • occurs in children during physeal closure (average age is 13 years old) 
        • juvenile ankle physis ossifies in specific order, which leads to transitional fractures such as triplane and tillaux fractures 
        • younger than tillaux fracture age group
  • Pathophysiology
    • mechanism of injury
      • lateral triplane fractures
        • results from supination-external rotation injury
          • similar to tillaux fractures
      • medial triplane fractures
        • results from adduction injury
    • pathoanatomy
      • a complex SH IV fracture pattern with components in all three planes
        • may be 2, 3, or 4 part fractures
          • epiphysis is often fractured on the lateral aspect in the sagittal plane (same as tillaux fracture) and is seen on the AP radiograph 
          • physis is separated in the axial plane
          • metaphysis is fractured on the posterior aspect in the coronal plane and is seen on the lateral radiograph
  • Associated conditions
    • fibular fractures
      • occurs in 50%
      • typically spiral fracture located proximal to the physis in children nearing skeletal maturity
      • remains unstable after fixation of tibia, so fixation of fibula is usually necessary
    • ipsilateral tibial shaft fractures
  • Physeal considerations
    • distal tibial physis
      • accounts for 35-40% of overall tibial growth and 15-20% of overall lower extremity growth
      • rate of growth is 3-4 mm/year
      • growth continues until 14 years in girls and 16 years in boys
      • closure occurs during an 18 month transitional period
        • occurs in a predictable pattern: central > anteromedial > posteromedial > lateral
  •  Parts
 Classification by Parts
2-part  • part 1 - anterolateral and posterior epiphysis is connected to the posterior metaphyseal fragment
 • part 2 - anteromedial epiphysis is connected to the remainder of the distal tibia
3-part  • part 1 - anteriolateral epiphysis
 • part 2 - posterior epiphysis is connected to the posterior metaphyseal fragment
 • part 3 - anteromedial epiphysis is connected to the remainder of the distal tibia
4-part  • comminuted variant
 • can only be distinguished from 3-part fractures via CT
  •  Pattern
 Classification by Pattern
Lateral triplane fracture
 • most common
 • epiphyseal fracture occurs in the sagittal plane
 • physeal fracture occurs in the axial plane

 • metaphyseal fracture occurs in the coronal plane
 • similar to tillaux fractures on AP radiographs (distinguish from tillaux fractures by SH II or I fracture on lateral radiograph)
Medial triplane fracture
 • epiphyseal fracture occurs in the coronal plane
 • physeal fracture occurs in the axial plane

 • metaphyseal fracture occurs in the sagittal plane
Intramalleolar triplane fracture
 • type I - intraarticular intramalleolar fracture involving the weight-bearing surface
 • type II - intraarticular intramalleolar fracture outside of the weight-bearing surface
 • type III - extraarticular intramalleolar fracture
  • Symptoms
    • pain
    • inability to bear weight
  • Physical exam
    • inspection
      • swelling
      • focal tenderness
      • deformity
  • Radiographs
    • recommended views
      • AP
      • lateral
      • mortise
        • best view to assess the amount of displacement
    • 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 SH III fracture  
      • lateral radiograph shows SH II fracture
  • CT scan 
    • indications
      • usually required to delineate fracture pattern and assess articular congruity
      • if closed reduction planned, consider CT after reduction to assess quality of reduction
    • findings
      • fracture involvement seen in all 3 planes 
      • Mercedes-Benz sign
  • Nonoperative
    • closed reduction and casting
      • indications
        • < 2mm displacement
      • techniques
        • ideal for 2-part fractures (difficult to achieve reduction of 3-part or 4-part fractures)
        • reduction maneuvers
          • reduce fibula fracture prior to attempting reduction of tibial fracture
          • for lateral triplane fractures, reduce with internal rotation
          • for medial triplane fractures, reduce with eversion
        • obtain post-reduction CT to assess reduction
        • long leg cast initially for 3-4 weeks to control rotational component of injury
          • follow early with radiographs to assess for displacement
        • immobilize an additional 2-4 weeks in a short leg cast or walking boot (to initiate ankle ROM)
  • Operative
    • CRPP vs. ORIF
      • indications
        • > 2mm displacement
  • CRPP vs. ORIF
    • approach
      • anterolateral approach for lateral triplane fractures
      • anteromedial approach for medial triplane fractures
    • reduction
      • for lateral triplane fractures, reduce with internal rotation
      • for medial triplane fractures, reduce with external rotation
      • arthroscopically-assisted reduction has been described
    • instrumentation
      • K wires or cannulated screws
      • epiphyseal screws placed parallel to physis 
      • metaphyseal fixation if component is large enough
    • post-op
      • long leg cast for 3-4 weeks then short leg walking cast for 2 weeks
    • complications specific to this treatment
      • hardware irritation
      • transient neuropathy
  • Growth arrest
    • occurs in 7-21%
    • risk factors
      • increased risk with pronation-abduction injuries compared to supination-external rotation injuries
      • increased risk with residual fracture displacement following reduction
    • usually insignificant but should closely follow patients with > 2 years of growth remaining
  • Ankle pain and degeneration
    • increased risk with articular step-off > 2mm

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Questions (2)

(OBQ06.160) Figures A and B show an AP and lateral radiographs of a 15-year old boy who injured his ankle after skateboarding. What is the mechanism of injury with this type of fracture? Review Topic

QID: 346

supination - adduction




external rotation




internal rotation




pronation - abduction




axial load



ML 2

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