title: [Posterior C1-C2 transarticular screw fixation for atlantoaxial instability assisted by intraoperative 3-dimensional fluoroscopy-based navigation].
abstract: OBJECTIVE
  To assess the feasibility, efficacy and indication of posterior C1-C2 transarticular screw fixation for atlantoaxial instability assisted by intraoperative 3-dimensional fluoroscopy-based navigation.
  
  
  METHODS
  From November 2005 to October 2012, 58 patients with atlantoaxial instability underwent posterior C1-C2 transarticular screw fixation assisted by intraoperative 3-dimensional fluoroscopy-based navigation. Those with excellent atlantoaxial reduction and no need for decompression underwent percutaneously minimally invasive procedures. Operative duration, blood loss volume, reduction of atlantoaxial joints and postoperative neurovascular complications were recorded. Screw positions were studied by postoperative computed tomography (CT) and divided into 3 categories. The follow-up period was at least 3 months. Local symptoms (assessed by visual analogue scale (VAS) score), neurological conditions (Nurick classification) and bone graft fusion were evaluated.
  
  
  RESULTS
  Among them, the procedure was either open surgery (n = 51) or percutaneously minimally invasive surgery (n = 7). A total of 111 screws were placed satisfactorily. Five patients underwent only unilateral C1-C2 transarticular screw fixation. No severe complications were encountered. The mean operative duration was 202.2 ± 54.2 minutes and the average volume of blood loss 412.6 ± 281.2 ml. And the values were comparable to those for the traditional fluoroscopy-guided free-hand procedures. No statistical significance existed between open and percutaneously minimally invasive procedures in operative duration, blood loss volume and precision of screw placement. The patients with incompletely reduced C1-C2 dislocation had comparable clinical outcomes with those with complete reduction. After a 3-month follow-up, all of them showed significant improvements of local symptoms. VAS score decreased from 4.5 ± 1.3 preoperatively to 0.7 ± 0.8 postoperatively while the Nurick classification improved from 2.4 ± 1.1 to 0.6 ± 1.0. And bone graft fusion was satisfactory.
  
  
  CONCLUSIONS
  Posterior C1-C2 transarticular screw fixation for atlantoaxial instability assisted by intraoperative 3-dimensional fluoroscopy-based navigation is both feasible and safe. Combined with minimally invasive techniques, this procedure may achieve greater precision and minimal invasion.
authors.affiliation: Department of Spine Surgery, Beijing Jishuitan Hospital, Beijing 100035, China.
authors.forename: Zhao
authors.initials: Z
authors.lastname: Lang
authors.forename: Wei
authors.initials: W
authors.lastname: Tian
authors.forename: Bo
authors.initials: B
authors.lastname: Liu
authors.forename: Qiang
authors.initials: Q
authors.lastname: Yuan
authors.forename: Da
authors.initials: D
authors.lastname: He
authors.forename: Yong-qing
authors.initials: YQ
authors.lastname: Wang
authors.forename: Ya-jun
authors.initials: YJ
authors.lastname: Liu
authors.forename: Ning
authors.initials: N
authors.lastname: Zhang
authors.forename: Yan
authors.initials: Y
authors.lastname: An
authors.forename: Yu-zhen
authors.initials: YZ
authors.lastname: Sun
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001268:Atlanto-Axial Joint / Q000000981:diagnostic imaging / Q000601:surgery; D001863:Bone Screws; D002574:Cervical Vertebrae / Q000601:surgery; D002648:Child; D005260:Female; D005471:Fluoroscopy; D006801:Humans; D016268:Internal Fixators; D007593:Joint Instability / Q000000981:diagnostic imaging / Q000601:surgery; D008297:Male; D008875:Middle Aged; D019060:Minimally Invasive Surgical Procedures / Q000295:instrumentation / Q000379:methods; D025321:Surgery, Computer-Assisted; D055815:Young Adult