The Levine and Edwards classification is the most widely used classification system of hangman fractures of the C2 vertebra ³. The injury, also known as traumatic spondylolisthesis of the axis, and the amount and direction of displacement determines stability and guides treatment. The classification system is a modified version of the original scheme described by Effendi ⁴. 

Classification

• type I: minimally displaced fracture with ≤3 mm antero-posterior translation
  • no angulation
  • C2/3 disc intact therefore no disc space widening
  • due to a hyperextension and axial loading mechanism
  • associated with atlas fractures, specifically Jefferson, odontoid process and posterior arch fractures
  • stable injury
  • treatment is collar immobilisation
• type II: displaced fracture with >3 mm antero-posterior translation
  • angulation of ≤10^o
  • vertical fracture line
  • the C2/3 disc and posterior longitudinal ligament are disrupted
  • due to a distractive flexion or compressive hyperextension mechanism
  • associated with C3 anterosuperior compression fractures and C2 endplate avulsion fractures
  • unstable injury
  • treatment depends on the degree of displacement and is either with halo immobilisation or surgery
• type IIa: type II fracture with minimal or no translation but marked angulation
  • angulation of >10^o
  • horizontal/oblique fracture line
  • significant angular deviation without anterior translation
  • anterior longitudinal ligament is intact
  • due to a similar mechanism as type II injuries
  • unstable injury
  • treatment is with a compression halo but traction needs to be avoided (as it increases fracture angulation)
• type III: type II fracture with bilateral facet joint dislocation
  • rare
  • due to a distractive flexion mechanism
  • treatment is surgery