title: Traumatic spondylolisthesis of the axis: a biomechanical comparison of clinically relevant anterior and posterior fusion techniques.
abstract: OBJECTIVE
  Surgical management of unstable traumatic spondylolisthesis of the axis includes both posterior and anterior fusion methods. The authors performed a biomechanical study to evaluate the relative stability of anterior fixation at C2-3 and posterior fixation of C-1 through C-3 in hangman's fractures.
  
  
  METHODS
  Fresh-frozen cadaveric spine specimens (occipital level to T-2) were subjected to stepwise destabilization of the C1-2 complex, replicating a Type II hangman's fracture. Intact specimens, fractured specimens, and fractured specimens with either anterior screw and plate or posterior screw and rod fixation were each tested for stability. Each spine was subjected to separate right and left rotation, bending, flexion, and extension testing.
  
  
  RESULTS
  Anterior fixation restored stiffness in flexion and extension movements to values greater than those for intact specimens. For other movement parameters, the values approximated those for intact specimens. Posterior fixation increased the stiffness to above those values seen for anterior fixation specimens.
  
  
  CONCLUSIONS
  In cadaveric spine specimens subjected to a Type II hangman's fracture, both anterior fixation at C2-3 and posterior fixation with C-1 lateral mass screws and C-2 and C-3 pedicle screws resulted in a consistent increase in stiffness, and hence in stability, over intact specimens.
authors.affiliation: Department of Neurosurgery, Louisiana State University Health Sciences Center-Shreveport, Shreveport, LA, USA.
authors.forename: Prashant
authors.initials: P
authors.lastname: Chittiboina
authors.forename: Esther
authors.initials: E
authors.lastname: Wylen
authors.forename: Alan
authors.initials: A
authors.lastname: Ogden
authors.forename: Debi P
authors.initials: DP
authors.lastname: Mukherjee
authors.forename: Prasad
authors.initials: P
authors.lastname: Vannemreddy
authors.forename: Anil
authors.initials: A
authors.lastname: Nanda
mesh_terms: D001368:Axis, Cervical Vertebra / Q000293:injuries / Q000503:physiopathology / Q000601:surgery; D001696:Biomechanical Phenomena; D001863:Bone Screws; D002102:Cadaver; D001270:Cervical Atlas / Q000293:injuries / Q000503:physiopathology / Q000601:surgery; D006801:Humans; D016103:Spinal Fractures / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery*; D013123:Spinal Fusion / Q000379:methods*; D013168:Spondylolisthesis / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery*; D014057:Tomography, X-Ray Computed