title: [Anatomic study on percutaneous anterior transarticular screw fixation by CT three-dimensional imaging].
abstract: OBJECTIVE
  To improve the safety of the percutaneous anterior transarticular screw fixation (PATSF) by measuring the parameters related to PATSF.
  
  
  METHODS
  Spiral CT scan and three-dimensional reconstructions of the atlanto-axis were performed in 50 adult volunteers. The section of inner margin of atlantal superior articular facet, the coronal plane vertebral artery cavity, and the sagittal plane of atlanto-axis were obtained with multiplanar reconstruction on helical CT. atlantoaxial vertebral structure and the direction of vertebral artery cavity were observed. The parameters related to PATSF measured and analysed.
  
  
  RESULTS
  The suitable position of screw insertion was 4.0 mm from the midpoint of the axoidean anteroinferior margin. The maximum external angle of PATSF was (29.89 +/- 1.41) degrees; the minimum external angle was (4.37 +/- 0.87) degrees; the maximum backward angle was (32.41 +/- 1.66) degrees; the optimal external angle was (17.13 +/- 0.88) degrees; the optimal backward was (17.62 +/- 1.03) degrees; and the optimal screw length was (41.57 +/- 0.79) mm. The atlantoaxial articular facial diameter was (16.71 +/- 1.61) mm; the maximum distance of atlantal lateral displacement was (6.96 +/- 1.09) mm; and the ratio of them was 41.80% 5.69%.
  
  
  CONCLUSIONS
  The optimal insertion of PATSF is safe and reliable. The screw can be inserted when the displacement the atlantal lateral mass is in a certain degree.
authors.affiliation: Department of Orthopedics, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, PR China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Lu
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.forename: Jie
authors.initials: J
authors.lastname: Liu
authors.forename: Wenqi
authors.initials: W
authors.lastname: Pan
mesh_terms: D000328:Adult; D000368:Aged; D001268:Atlanto-Axial Joint / Q000000981:diagnostic imaging* / Q000601:surgery; D001863:Bone Screws; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult