title: In vitro simulation. Early results of stereotaxy for pedicle screw placement.
abstract: METHODS
  Frameless stereotaxy with doppler ultrasound and three dimensional computer model registration is assessed in vitro for pedicle screw placement.
  
  
  OBJECTIVE
  To identify feasibility of pedicle screw navigation and placement using this technology.
  
  
  BACKGROUND
  Inaccurate pedicle screw placement can lead to neurovascular injury or suboptimal fixation. Present techniques in pedicle screw placement involve only confirmation of hole orientation.
  
  
  METHODS
  Forty-four pedicle screws were placed in lumbosacral models and cadaver specimens. Accuracy was assessed with a computed tomography scan and vertebral cross sectioning.
  
  
  RESULTS
  All screws were intrapedicular. Accuracy of anterior cortical fixation was 1.5 mm, with a range of 2.5 mm.
  
  
  CONCLUSIONS
  In vitro frameless stereotaxy is accurate for pedicle screw placement. This technology adds a component of navigation to pedicle screw placement.
authors.affiliation: Division of Orthopaedic Surgery, Albany Medical College, New York, USA.
authors.forename: A L
authors.initials: AL
authors.lastname: Carl
authors.forename: H S
authors.initials: HS
authors.lastname: Khanuja
authors.forename: B L
authors.initials: BL
authors.lastname: Sachs
authors.forename: C A
authors.initials: CA
authors.lastname: Gatto
authors.forename: J
authors.initials: J
authors.lastname: vomLehn
authors.forename: K
authors.initials: K
authors.lastname: Vosburgh
authors.forename: J
authors.initials: J
authors.lastname: Schenck
authors.forename: W
authors.initials: W
authors.lastname: Lorensen
authors.forename: K
authors.initials: K
authors.lastname: Rohling
authors.forename: D
authors.initials: D
authors.lastname: Disler
mesh_terms: D001863:Bone Screws; D002102:Cadaver; D003198:Computer Simulation; D005240:Feasibility Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008159:Lumbar Vertebrae / Q000601:surgery*; D012447:Sacrum / Q000601:surgery*; D013238:Stereotaxic Techniques; D014057:Tomography, X-Ray Computed