title: Intraoperative, full-rotation, three-dimensional image (O-arm)-based navigation system for cervical pedicle screw insertion.
abstract: OBJECTIVE
  The aim of this study was to retrospectively evaluate the reliability and accuracy of cervical pedicle screw (CPS) placement using an intraoperative, full-rotation, 3D image (O-arm)-based navigation system and to assess the advantages and disadvantages of the system.
  
  
  METHODS
  The study involved 21 consecutive patients undergoing posterior stabilization surgery of the cervical spine between April and December 2009. The patients, in whom 108 CPSs had been inserted, underwent screw placement based on intraoperative 3D imaging and navigation using the O-arm system. Cervical pedicle screw positions were classified into 4 grades, according to pedicle-wall perforations, by using postoperative CT.
  
  
  RESULTS
  Of the 108 CPSs, 96 (88.9%) were classified as Grade 0 (no perforation), 9 (8.3%) as Grade 1 (perforations < 2 mm, CPS exposed, and < 50% of screw diameter outside the pedicle), and 3 (2.8%) as Grade 2 (perforations between ≥ 2 and < 4 mm, CPS breached the pedicle wall, and > 50% of screw diameter outside the pedicle). No screw was classified as Grade 3 (perforation > 4 mm, complete perforation). No neurovascular complications occurred because of CPS placement.
  
  
  CONCLUSIONS
  The O-arm offers high-resolution 2D or 3D images, facilitates accurate and safe CPS insertion with high-quality navigation, and provides other substantial benefits for cervical spinal instrumentation. Even with current optimized technology, however, CPS perforation cannot be completely prevented, with 8.3% instances of minor violations, which do not cause significant complications, and 2.8% instances of major pedicle violations, which may cause catastrophic complications. Therefore, a combination of intraoperative 3D image-based navigation with other techniques may result in more accurate CPS placement.
authors.affiliation: Department of Orthopedic Surgery, Spine Center, Konan Kosei Hospital, Takaya Chou, Konan City, Japan. chita.peninsula@gmail.com
authors.forename: Yoshimoto
authors.initials: Y
authors.lastname: Ishikawa
authors.forename: Tokumi
authors.initials: T
authors.lastname: Kanemura
authors.forename: Go
authors.initials: G
authors.lastname: Yoshida
authors.forename: Akiyuki
authors.initials: A
authors.lastname: Matsumoto
authors.forename: Zenya
authors.initials: Z
authors.lastname: Ito
authors.forename: Ryoji
authors.initials: R
authors.lastname: Tauchi
authors.forename: Akio
authors.initials: A
authors.lastname: Muramoto
authors.forename: Shuichiro
authors.initials: S
authors.lastname: Ohno
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Nishimura
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001863:Bone Screws; D002574:Cervical Vertebrae / Q000601:surgery*; D005260:Female; D005471:Fluoroscopy / Q000379:methods*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012399:Rotation; D013122:Spinal Diseases / Q000601:surgery*; D013123:Spinal Fusion / Q000295:instrumentation / Q000379:methods*; D025321:Surgery, Computer-Assisted / Q000379:methods; D016896:Treatment Outcome