title: Axial translaminar screw placement using three-dimensional fluoroscopy-based navigation.
abstract: BACKGROUND
  To circumvent the risk to the vertebral artery with C2 pars or pedicle screws, C2 laminar screws were considered as a method for rigid fixation of the axis. Although considered to be a relatively safe method, ventral spinal canal violations have been reported. Three-dimensional (3D) fluoroscopy-based image guidance may enhance the accuracy and safety of the technique. There is only one previous report in the literature on its use in the placement of C2 laminar screws. The purpose of this study was to assess the accuracy of C2 translaminar screws inserted using 3D fluoroscopy-based navigation.
  
  
  METHODS
  Data from a single centre was gathered retrospectively and then analysed. 3D fluoroscopy-based navigation was used to insert five translaminar screws in four patients (two male, two female). Their mean age was 45.3 years and the average follow-up period was 13.8 months. The accuracy of screw placement and fusion was ascertained using postoperative computed tomography imaging.
  
  
  RESULTS
  There were no complications in this series. No breach in the dorsal or ventral laminar wall was noted for any of the translaminar screws inserted. The average time required to set up the navigation platform and screen was 18 minutes. Successful fusion was observed in all four patients at six months follow-up.
  
  
  CONCLUSIONS
  Although considered a relatively safe technique, laminar cortical violations have been reported with C2 translaminar screws. 3D fluoroscopy-based image guidance can greatly enhance the accuracy of C2 translaminar screw insertion, as this technology provides real-time images during screw insertion and permits accurate screw sizing.
authors.affiliation: Department of Orthopaedics and Spine Surgery, Ganga Hospital, 313 Mettupalayam Road, Coimbatore 641043, Tamil Nadu, India. sr@gangahospital.com
authors.forename: S
authors.initials: S
authors.lastname: Rajasekaran
authors.forename: A
authors.initials: A
authors.lastname: Avadhani
authors.forename: A P
authors.initials: AP
authors.lastname: Shetty
mesh_terms: D000328:Adult; D001268:Atlanto-Axial Joint / Q000000981:diagnostic imaging / Q000473:pathology; D001863:Bone Screws; D005260:Female; D005471:Fluoroscopy / Q000379:methods*; D005500:Follow-Up Studies; D006801:Humans; D021621:Imaging, Three-Dimensional; D016268:Internal Fixators; D008297:Male; D008875:Middle Aged; D009985:Orthopedics / Q000379:methods; D012189:Retrospective Studies; D012984:Software; D013123:Spinal Fusion / Q000379:methods*