title: Comparison of the anatomical risk for vertebral artery injury associated with the C2-pedicle screw and atlantoaxial transarticular screw.
abstract: METHODS
  We evaluated the trajectories of atlantoaxial transarticular and C2-pedicle screws in 3 dimensions using computerized tomography.
  
  
  OBJECTIVE
  To compare the anatomic risk for vertebral artery injury associated with C2-pedicle and atlantoaxial transarticular screws.
  
  
  BACKGROUND
  The atlantoaxial fixation technique using C1-lateral mass screws combined with C2-pedicle screws is considered a safer technique for preventing vertebral artery injury than atlantoaxial transarticular fixation. However, few reports have compared the anatomic risk of vertebral artery injury associated with C2-pedicle screws with that of transarticular screws.
  
  
  METHODS
  A total of 62 consecutive patients with cervical lesions were evaluated using 3-dimensional images reconstructed by a computer-assisted navigation system. We compared the maximum possible diameters of the atlantoaxial transarticular screw and C2-pedicle screw trajectories, and examined whether the maximum possible diameters were limited by the height or width of the bony structure in screw trajectories < or = 4 mm in diameter.
  
  
  RESULTS
  Mean maximum possible diameters did not differ significantly between the trajectories of 124 atlantoaxial transarticular and 124 C2-pedicle screws. In screw trajectories < or = 4 mm in diameter, 57.1% of transarticular screw trajectories were limited by the height of the bony structure, and all pedicle screw trajectories were limited by the width.
  
  
  CONCLUSIONS
  C2-pedicle screw placement has nearly the same anatomic risk of vertebral artery injury as transarticular screw placement. Preoperative 3-dimensional evaluation may be useful for choosing the best surgical technique.
authors.affiliation: Department of Orthopaedic Surgery, Kyoto University Graduate School of Medicine, Shogoin, Kyoto, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Yoshida
authors.forename: Masashi
authors.initials: M
authors.lastname: Neo
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Fujibayashi
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakamura
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001172:Arthritis, Rheumatoid / Q000000981:diagnostic imaging / Q000601:surgery; D001268:Atlanto-Axial Joint / Q000000981:diagnostic imaging / Q000293:injuries / Q000601:surgery*; D001368:Axis, Cervical Vertebra / Q000000981:diagnostic imaging / Q000293:injuries / Q000601:surgery; D001863:Bone Screws / Q000009:adverse effects*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control; D012307:Risk Factors; D013122:Spinal Diseases / Q000000981:diagnostic imaging / Q000601:surgery*; D013123:Spinal Fusion / Q000009:adverse effects* / Q000295:instrumentation / Q000379:methods; D013125:Spinal Neoplasms / Q000000981:diagnostic imaging / Q000556:secondary / Q000601:surgery; D014057:Tomography, X-Ray Computed / Q000379:methods; D014711:Vertebral Artery / Q000293:injuries* / Q000601:surgery; D014911:Whiplash Injuries / Q000000981:diagnostic imaging / Q000601:surgery