title: Torticollis of a specific C1 dislocation with split atlas.
abstract: METHODS
  A case report.
  
  
  OBJECTIVE
  We report a novel case of torticollis disorder because of a congenital split atlas after minor trauma.
  
  
  BACKGROUND
  Torticollis experienced after minor trauma in childhood is usually because of atlantoaxial rotatory fixation, which is a common disorder in pediatric patients and is usually diagnosed with computed tomography (CT). CT scanning with 3-dimensional reconstruction, however, showed a unique rotation of split atlas, a congenital anomaly that presented with torticollis.
  
  
  METHODS
  A female child aged 3 years and 11 months presented to the orthopedic clinic with torticollis after a fall. CT imaging showed no rotatory dislocation of C1-C2. On the 3-dimensional CT reconstruction images, however, anterior and posterior defects in the atlas, the so-called split atlas, and an atypical rotation with malalignment of the posterior arch and asymmetry of the atlantoaxial facet joint were noted. The child was treated with closed reduction using skull traction under general anesthesia.
  
  
  RESULTS
  Repositioning of the atlas rotation was confirmed using intraoperative 3-dimensional scanning, and open reduction therapy was avoided. The patient was treated with halo vest for 8 weeks and had full recovery of neck motion with resolution of the torticollis.
  
  
  CONCLUSIONS
  We present a novel torticollis disorder caused by C1 rotation of a split atlas with closed reduction treatment.
authors.affiliation: Department of Orthopedics, National Defense Medical College, Saitama, Japan. hotchild53@hotmail.co.jp
authors.forename: Atsuko
authors.initials: A
authors.lastname: Tachibana
authors.forename: Hideaki
authors.initials: H
authors.lastname: Imabayashi
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Yato
authors.forename: Kiyohiro
authors.initials: K
authors.lastname: Nakamichi
authors.forename: Takashi
authors.initials: T
authors.lastname: Asazuma
authors.forename: Koichi
authors.initials: K
authors.lastname: Nemoto
mesh_terms: D001268:Atlanto-Axial Joint / Q000293:injuries*; D001270:Cervical Atlas; D002675:Child, Preschool; D005260:Female; D006801:Humans; D004204:Joint Dislocations / Q000150:complications* / Q000175:diagnosis; D019637:Orthopedic Procedures / Q000379:methods; D014057:Tomography, X-Ray Computed; D014103:Torticollis / Q000209:etiology / Q000601:surgery*; D016896:Treatment Outcome