title: Pedicle screw insertion in the thoracolumbar spine: comparison of 4 guidance techniques in the intact cadaveric spine.
abstract: OBJECTIVE
  Pedicle screw fixation is a mainstay of thoracolumbar stabilization. Screw insertion using anatomical landmarks and fluoroscopy is common but can be technically challenging and generally involves substantial exposure to ionizing radiation. Computerized navigation has been reported to improve accuracy but is expensive and complex. The authors undertook this study to evaluate these 3 methods in comparison with a fourth technique using standard cervical distractor screws to mark the entry point and trajectory.
  
  
  METHODS
  Four cadaveric human spines were used for this study. After an initial CT scan, 34 pedicle screws were inserted in each intact spine from T-1 to L-5 using the following 4 screw insertion guidance techniques (1 technique per specimen): use of anatomical landmarks, use of cervical distractor screws and spot fluoroscopy, fluoroscopy-based navigation, and fluoroscopy- and CT-based navigation (using merged imaging data). Postprocedural CT and anatomical dissection were then performed to evaluate screw position for site and degree of breach.
  
  
  RESULTS
  The cervical distractor screw method had a breach rate of 5.9% versus 29.4%, 32.4%, and 20.6% for use of anatomical landmarks, fluoroscopic navigation, and fluoroscopic-CT navigation, respectively (p < 0.05). There is also a significant association between degree of medial and distal breach and the method of screw insertion (p < 0.05).
  
  
  CONCLUSIONS
  Cervical distractor screws as pedicle markers offer favorable insertion accuracy and reduction of radiation exposure compared with the other 3 methods used in clinical practice.
authors.affiliation: Edmonton Spine Fellowship Program, University of Alberta, Edmonton, Alberta, Canada. Husam.alhabib@gmail.com
authors.forename: Husam
authors.initials: H
authors.lastname: Alhabib
authors.forename: Andrew
authors.initials: A
authors.lastname: Nataraj
authors.forename: Mohammed
authors.initials: M
authors.lastname: Khashab
authors.forename: James
authors.initials: J
authors.lastname: Mahood
authors.forename: Frank
authors.initials: F
authors.lastname: Kortbeek
authors.forename: Richard
authors.initials: R
authors.lastname: Fox
mesh_terms: D001863:Bone Screws; D002102:Cadaver; D005471:Fluoroscopy; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D011475:Prosthesis Failure; D015641:Radiography, Interventional / Q000379:methods*; D015203:Reproducibility of Results; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D014057:Tomography, X-Ray Computed / Q000379:methods*