title: Accuracy of lower cervical pedicle screw placement with assistance of distinct navigation systems: a human cadaveric study.
abstract: OBJECTIVE
  Evaluate the accuracy of five different techniques for lower cervical pedicle screw placement.
  
  
  METHODS
  Forty human cadaveric cervical spines were equally divided into five groups, and each group had eight specimens. Pedicle screws with dia. 3.5 mm were used. Group 1 was blind screw placement without any assistance; Group 2-5 was assisted by the X-ray fluoroscopy, virtual fluoroscopy navigation system, CT-based navigation system, and Iso-C 3D navigation system, respectively. Thereafter, cortical integrity of each pedicle was evaluated by anatomic dissection of the specimens.
  
  
  RESULTS
  A total of 398 pedicle screws were inserted. In the Group 1-5, the average operation time per sample was 27 ± 3.0, 112 ± 10.3, 69 ± 6.4, 98 ± 11.0, and 91 ± 6.0 min, respectively. The outcome for excellent, fair and poor were 29 (36.3 %), 21 (26.2 %) and 30 (37.5 %) in Group 1; 35 (44.9 %), 29 (37.2 %) and 14 (17.9 %) in Group 2; 34 (42.5 %), 36 (45.0 %) and 10 (12.5 %) in Group 3; 70 (87.5 %), 10 (12.5 %) and 0 (0.0 %) in Group 4; 72 (90.0 %), 8 (10.0 %) and 0 (0.0 %) in Group 5.
  
  
  CONCLUSIONS
  Blind screw placement was surely unsafe. Lower cervical pedicle screw placement assisted by the CT-based navigation system or the Iso-C 3D navigation system significantly improved the accuracy compared to the fluoroscopy assistance and the virtual fluoroscopy navigation assistance.
authors.affiliation: Department of Spine Surgery, Beijing Jishuitan Hospital (4th Clinical Medical College of Peking University), No. 31, Xinjiekou East Street, Xicheng District, 100035 Beijing, People's Republic of China. drtianweia@163.com
authors.forename: Wei
authors.initials: W
authors.lastname: Tian
authors.forename: Yajun
authors.initials: Y
authors.lastname: Liu
authors.forename: Shan
authors.initials: S
authors.lastname: Zheng
authors.forename: Yanwei
authors.initials: Y
authors.lastname: Lv
mesh_terms: D001863:Bone Screws; D002102:Cadaver; D002574:Cervical Vertebrae / Q000601:surgery*; D006801:Humans; D021621:Imaging, Three-Dimensional; D013123:Spinal Fusion / Q000295:instrumentation / Q000379:methods*; D025321:Surgery, Computer-Assisted / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods