title: [The synthetic typing and its clinical application in atlantoaxial dislocation].
abstract: OBJECTIVE
  To evaluate the synthetic typing and the treatment strategy for atlantoaxial dislocation.
  
  
  METHODS
  The synthetic typing of atlantoaxial dislocation was worked out on the base of pathogenesis typing, Fielding imaging typing, and clinical typing, named PIR typing system (Pathogenesis, Imaging, and Reduction). Ninety-three patients with atlantoaxial dislocation were treated according to this typing system.
  
  
  RESULTS
  Nine cases of type-II dens fracture were treated with hollow screw fixation. Bone union was accomplished at the follow-up of three months in all the patients, only with slight limitation of cervical motion. Un-retrieved Fielding I -degree dislocation was found in one case. Among the thirty-four patients treated with trans-oropharyngeal atlantoaxial reduction plate system (TARP), 32 obtained complete atlantoaxial reduction and fusion three months after operation. Atlantoaxial dislocation recurred in the other two cases because of screw loosening and the problem was solved through revision operations. Four patients in non-reducible type underwent anterior and/or posterior decompression. T heir neurological improved after operation but their atlantoaxial joints remained dislocated, and one case complicated with intracranial infection.
  
  
  CONCLUSIONS
  Via the synthetic PIR typing system, atlantoaxial dislocation can be better classified according to its pathogenesis, imaging manifestation and mechanic stability. This system can also be served as a guide for clinical treatment. Anterior TARP operation and posterior atlantoaxial trans-pedicle screw-rod fixation are the main methods for the treatment of atlantoaxial dislocation.
authors.affiliation: Department of Orthopedics, Guangzhou General Hospital of Guangzhou Military Command, Guangzhou 510010, China. gz-yqs@126.com
authors.forename: Qing-shui
authors.initials: QS
authors.lastname: Yin
authors.forename: Yun-bing
authors.initials: YB
authors.lastname: Chang
authors.forename: Hong
authors.initials: H
authors.lastname: Xia
authors.forename: Zheng-hui
authors.initials: ZH
authors.lastname: Wu
authors.forename: Fu-zhi
authors.initials: FZ
authors.lastname: Ai
authors.forename: Ri
authors.initials: R
authors.lastname: Quan
authors.forename: Xiang-yang
authors.initials: XY
authors.lastname: Ma
authors.forename: Kai
authors.initials: K
authors.lastname: Zhang
authors.forename: Zheng-lin
authors.initials: ZL
authors.lastname: Cao
authors.forename: Jian-hua
authors.initials: JH
authors.lastname: Wang
mesh_terms: D000293:Adolescent; D000328:Adult; D001268:Atlanto-Axial Joint; D001860:Bone Plates; D001863:Bone Screws; D002648:Child; D019299:Decompression, Surgical; D005260:Female; D005500:Follow-Up Studies; D005593:Fracture Fixation, Internal / Q000379:methods*; D006801:Humans; D004204:Joint Dislocations / Q000145:classification* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D013123:Spinal Fusion