title: [Posterior fixation and fusion for treatment of Os odontoideum complicated by atlantoaxial dislocation].
abstract: OBJECTIVE
  To summarize the techniques and evaluate the therapeutic effect of posterior fixation and fusion in the treatment of Os odontoideum complicated by atlantoaxial dislocation.
  
  
  METHODS
  From March, 2007 to October, 2010, 10 patients with Os odontoideum (including 6 male and 4 female patients aged from 20 to 65 years, mean 39.8 years) were treated in our hospital. Before and after the operation, the patients underwent X ray, CT and MRI examinations to measure and evaluate the degree of dislocation and neural compression. After preoperative traction for 1-2 weeks, all the 10 patients showed deductible atlantoaxial dislocation. Through a posterior approach, Atlantoaxial pedicle screws fixation were performed in 9 cases, and C2/3 pedicle-Occiput screw fixation was performed in 1 case. All the patients wore cervical collars as external support for 3 months after the operation.
  
  
  RESULTS
  The mean operative time was 3 h in these patients with a mean intraoperative blood loss of 420 ml. The symptoms were relieved after the surgery in all the patients, who showed no neck pain or neurological defects. The patients were followed up for 6 to 52 months (mean 22 months), and bony fusion was observed in all the 10 cases within 6 to 8 months without such complications as internal fixation failure or redislocation of the atlas.
  
  
  CONCLUSIONS
  Patients with Os odontoideum complicated by atlantoaxial dislocation should undergo surgical stabilization to avoid severe neurological injury. Pedicle screw instrument in the atlas allows restoration of the spinal stability, short-segment fusion, and maximal preservation of the mobility of the neck.
authors.affiliation: Department of Orthopedics, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China. zhanghuixf@163.com
authors.forename: Hui
authors.initials: H
authors.lastname: Zhang
authors.forename: Anmin
authors.initials: A
authors.lastname: Jin
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.forename: Zhilai
authors.initials: Z
authors.lastname: Zhou
authors.forename: Yang
authors.initials: Y
authors.lastname: Duan
authors.forename: Shaoxiong
authors.initials: S
authors.lastname: Min
mesh_terms: D000328:Adult; D000368:Aged; D001268:Atlanto-Axial Joint / Q000293:injuries; D016025:Bone Transplantation; D005260:Female; D005593:Fracture Fixation, Internal / Q000379:methods*; D006801:Humans; D004204:Joint Dislocations / Q000150:complications / Q000601:surgery*; D007594:Joint Loose Bodies / Q000150:complications / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009809:Odontoid Process / Q000473:pathology; D013123:Spinal Fusion / Q000379:methods; D016896:Treatment Outcome; D055815:Young Adult