title: Posterior C1-C2 screw and rod instrument for reduction and fixation of basilar invagination with atlantoaxial dislocation.
abstract: OBJECTIVE
  To report the surgical technique and preliminary clinical results for the treatment of basilar invagination (BI) with atlantoaxial dislocation (AAD) by posterior C1-C2 pedicle screw and rod instrument.
  
  
  METHODS
  Between July 2012 and August 2013, 33 patients who had BI with AAD underwent surgery at our institution. Pre and postoperative three-dimensional computed tomographic (CT) scans were performed to assess the degree of dislocation. Magnetic resonance (MR) imaging was used to evaluate the compression of the medulla oblongata. For all patients, reduction of the AAD was conducted by two steps: fastening nuts and rods was performed to achieve the horizontal reduction. Distraction between C1 and C2 screws was performed to obtain the vertical reduction.
  
  
  RESULTS
  No neurovascular injury occurred during surgery. Follow-up ranged from 6 to 15 months (mean 10.38 months) in 32 patients. Post-operative three-dimensional CT showed that complete horizontal reduction was obtained in 30/33 (90.9%), and complete vertical reduction was obtained in 31/33 (93.9%). The repeated three-dimensional CT and MR image demonstrated that bony fusion and the decompression of the medulla oblongata were obtained in all patients. Clinical symptoms improved significantly 3 months after surgery.
  
  
  CONCLUSIONS
  This C1-C2 pedicle screw and rod instrument is a promising technique for the treatment of BI with AAD.
authors.affiliation: Department of Neurosurgery, PLA General Hospital, 28 Fuxing Rd, Beijing, 100853, China.
authors.forename: Sheng Li
authors.initials: SL
authors.lastname: Guo
authors.forename: Ding Biao
authors.initials: DB
authors.lastname: Zhou
authors.forename: Xin Guang
authors.initials: XG
authors.lastname: Yu
authors.forename: Yi Heng
authors.initials: YH
authors.lastname: Yin
authors.forename: Guang Yu
authors.initials: GY
authors.lastname: Qiao
mesh_terms: D000293:Adolescent; D000328:Adult; D001268:Atlanto-Axial Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D019299:Decompression, Surgical / Q000295:instrumentation / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D016268:Internal Fixators; D004204:Joint Dislocations / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D065289:Pedicle Screws; D010985:Platybasia / Q000000981:diagnostic imaging / Q000601:surgery*; D011446:Prospective Studies; D011859:Radiography; D055815:Young Adult