title: Atlantoaxial rotatory subluxation with ankylosis in an 11-year-old girl: a case report.
abstract: METHODS
  Report of an 11-year-old girl with a left atlantoaxial rotatory subluxation and ankylosis found 20 months after she sustained a cervical injury.
  
  
  OBJECTIVE
  To describe the radiographic characteristics of this rare deformity assessed with a combination of spiral CT scan with multiplanar three-dimensional reformations and functional CT scan.
  
  
  BACKGROUND
  Atlantoaxial rotatory subluxation is a well-known condition, but its association with lateral C1-C2 ankylosis has not been reported to our knowledge.
  
  
  METHODS
  For a complete assessment of the dislocation, a combined morphologic volumetric and functional CT study was performed.
  
  
  RESULTS
  Spiral CT showed an atlantoaxial rotatory subluxation with lateral C1-C2 ankylosis. CT study also demonstrated a lateral C1-C2 subluxation and an ipsilateral occipitoatlantal subluxation. Cervical MRI showed no spinal cord compression despite the seriousness of the dislocation process.
  
  
  CONCLUSIONS
  Whereas "classic" spiral study with multiplanar and three-dimensional reformations allows precise assessment of relationships between the upper cervical vertebrae, as well as bony changes, a functional CT study is essential for cervical biomechanic assessment of rotational instabilities of the craniovertebral junction and upper cervical spine.
authors.affiliation: Hotel-Dieu, Radiology Department, Nantes, France. hredon@club-internet.fr
authors.forename: Hervé
authors.initials: H
authors.lastname: Redon
authors.forename: C
authors.initials: C
authors.lastname: Iacona
authors.forename: G
authors.initials: G
authors.lastname: Lot
authors.forename: J D
authors.initials: JD
authors.lastname: Laredo
mesh_terms: D000844:Ankylosis / Q000000981:diagnostic imaging / Q000209:etiology*; D001268:Atlanto-Axial Joint / Q000000981:diagnostic imaging / Q000503:physiopathology*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D004204:Joint Dislocations / Q000000981:diagnostic imaging / Q000209:etiology*; D019838:Neck Injuries / Q000150:complications*; D012399:Rotation; D036542:Tomography, Spiral Computed; D014103:Torticollis / Q000209:etiology*