title: [Atlanto-axial pedicle screw fixation through posterior approach for treatment of atlanto-axial joint instability].
abstract: OBJECTIVE
  To discuss the therapeutic effects of the atlantoaxial pedicle screw system fixation in treatment of atlantoaxial instability.
  
  
  METHODS
  From June 2003 to March 2010, 32 patients with atlantoaxial instability were treated by atlantoaxial pedicle screw system fixation, included 21 males and 11 females wiht an average age of 42.5 years old ranging from 28 to 66 years. Among them, 18 cases were odontoid process fractures, 7 were congenital dissociate odontoid process, 4 were Jefferson fracture combined with odontoid fracture, 3 were rheumatic arthritis causing atlantoaxial instability. All patients suffered from the atlantoaxial subluxation and atlantoaxial instability. The JOA score ranged from 4 to 14 (means 9.1 +/- 0.3) before operation. The patients had some image examination including the X-ray of cervical vertebrae (include of dynamic position film), spiral CT 3D reconstruction and/or MRI. The position of pedicle screw system implantation,the angle of pedicle screw system implantation and screw length were measured. Operating skull traction. Operation undewent general anesthesia, implanted the pedicle screw, reduction and bone fusion under direct vision. The bone was fixated between posterior arch of atlas and lamina of axis by the lateral combination bended to posterior.
  
  
  RESULTS
  One hundred and twenty-eight atlantoaxial pedicle screws were implanted in 32 patients. No patient had the injure of spinal cord, nerve root and vertebral artery. All patients were followed-up from 6 to 48 months (averaged 16 months). After operation, the JOA score ranged from 11 to 17 (averaged 15.9 +/- 0.2), improvement rate was 86.1%. The fracture of odontoid process were healing completely. All fusion bone were combinated. The internal fixation wasn't loosening and breaking.
  
  
  CONCLUSIONS
  The atlantoaxial pedicle screw system fixation was effective method to treat atlantoaxial instability. The method had many advantages, such as provide rigid and short segment fixation, safe and simple, high fusion rate. The method was worth in clinical application.
authors.affiliation: Department of Spinal Surgery, Baoji Municipal Central Hospital, Baoji 721008, Shaanxi, China. rainmanlxj@msn.com
authors.forename: Chun-Guang
authors.initials: CG
authors.lastname: Zuo
authors.forename: Xia-Jun
authors.initials: XJ
authors.lastname: Liu
authors.forename: Xin-Hu
authors.initials: XH
authors.lastname: Wang
authors.forename: Jian-shun
authors.initials: JS
authors.lastname: Wang
mesh_terms: D000328:Adult; D000368:Aged; D001268:Atlanto-Axial Joint / Q000000981:diagnostic imaging / Q000293:injuries* / Q000601:surgery; D001696:Biomechanical Phenomena; D001863:Bone Screws; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D014057:Tomography, X-Ray Computed