title: Posterolateral dislocation of the C1-C2 articulation associated with fracture of the anterior arch of C1: a case report.
abstract: METHODS
  Case report.
  
  
  OBJECTIVE
  To report a rare traumatic C1-C2 dislocation associated with fracture of the anterior arch of the atlas in a neurologically intact patient.
  
  
  BACKGROUND
  Isolated fractures of the anterior arch of C1 are very rare. There have been reports of horizontal fractures of the anterior arch thought to occur secondary to hyperextension injuries with subsequent avulsion of the anterior tubercle of the atlas. To our knowledge, however, there are no previously reported cases of isolated anterior arch fractures of C1 associated with posterolateral dislocation of the C1-C2 articulation.
  
  
  METHODS
  A 53-year-old patient who presented with a posterolateral dislocation of the C1-C2 articulation and an associated anterior arch fracture of C1 is reported. Details of the initial presentation, diagnostic strategy, and initial and definitive management are provided.
  
  
  RESULTS
  Closed reduction with halo ring application and gentle manipulation was followed with definitive internal fixation consisting of Magerl C1-C2 transarticular screw fixation coupled with modified Brooks fusion.
  
  
  CONCLUSIONS
  Posterolateral C1-C2 dislocation associated with atlantal anterior arch fracture is a rare injury that can be effectively treated with gentle closed reduction under fluoroscopic guidance followed by internal fixation with or without halo vest immobilization. Recognition of associated conditions including vertebral artery compromise, concomitant cervical spine fractures, and life-threatening injuries is paramount to the successful treatment of these patients.
authors.affiliation: University of Calgary Spine Program, Division of Neurosurgery, Department of Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada. jason_james_howard@msn.com
authors.forename: Jason J
authors.initials: JJ
authors.lastname: Howard
authors.forename: Stephan J
authors.initials: SJ
authors.lastname: Duplessis
mesh_terms: D001268:Atlanto-Axial Joint / Q000293:injuries / Q000473:pathology*; D001270:Cervical Atlas / Q000293:injuries / Q000473:pathology*; D002574:Cervical Vertebrae / Q000473:pathology*; D005260:Female; D005593:Fracture Fixation, Internal; D006801:Humans; D004204:Joint Dislocations / Q000209:etiology / Q000473:pathology* / Q000601:surgery; D008875:Middle Aged; D016103:Spinal Fractures / Q000150:complications / Q000473:pathology* / Q000601:surgery; D016896:Treatment Outcome