title: Image-guided insertion of transpedicular screws. A laboratory set-up.
abstract: METHODS
  A computer-assisted system allowing precise preoperative planning and real-time intraoperative image localization of surgical instruments is tested in a laboratory setup.
  
  
  OBJECTIVE
  The purpose of this study is to assess the applicability, functionality, and accuracy of this transpedicular spinal fixation technique.
  
  
  BACKGROUND
  Most techniques in transpedicular spinal fixation rely on the identification of predefined targets with the help of anatomic landmarks and on the intraoperative use of image intensifiers. Various studies report considerable screw misplacement rates which may lead to serious clinical sequelae such as permanent nerve damage.
  
  
  METHODS
  The proposed system was tested in an in vitro setup drilling 20 pedicle pilot holes in lumbar vertebrae. The accuracy was assessed using precision cuts through the pedicles and simulation of a 6-mm pedicle screw insertion.
  
  
  RESULTS
  An ideal screw position was found in 70 of 77 cuts, and in no case was an injury to the pedicular cortex observed.
  
  
  CONCLUSIONS
  The presented technique provides a safe, accurate, and flexible basis for transpedicular screw placement in the spine. This approach should be further evaluated in clinical applications.
authors.affiliation: M. E. Müller Institute for Biomechanics, University of Bern, Switzerland.
authors.forename: L P
authors.initials: LP
authors.lastname: Nolte
authors.forename: L J
authors.initials: LJ
authors.lastname: Zamorano
authors.forename: Z
authors.initials: Z
authors.lastname: Jiang
authors.forename: Q
authors.initials: Q
authors.lastname: Wang
authors.forename: F
authors.initials: F
authors.lastname: Langlotz
authors.forename: U
authors.initials: U
authors.lastname: Berlemann
mesh_terms: D001863:Bone Screws; D006801:Humans; D007091:Image Processing, Computer-Assisted; D013131:Spine / Q000000981:diagnostic imaging* / Q000601:surgery*; D013238:Stereotaxic Techniques / Q000295:instrumentation; D013813:Therapy, Computer-Assisted; D014057:Tomography, X-Ray Computed