title: Comparative results between conventional and computer-assisted pedicle screw installation in the thoracic, lumbar, and sacral spine.
abstract: METHODS
  A comparative study on the position of pedicle screws in patients treated surgically with and without computer assistance.
  
  
  OBJECTIVE
  To evaluate the accuracy of computer-assisted pedicle screw installation, and to evaluate its clinical benefit as compared with conventional pedicle screw installation techniques.
  
  
  BACKGROUND
  In vitro and clinical studies have documented a significant rate of misplaced screws in the thoracolumbar area. Neurologic complications are recognized problems caused by screw misplacement.
  
  
  METHODS
  Patients treated surgically with computer assistance were compared with a historical control group of patients treated surgically with conventional techniques in the same hospital and by the same surgical team. All screw positions were measured with a postoperative magnetic resonance tomography, and cortical effractions were categorized in 2-mm increments. Patients' charts also were reviewed to assess individual neurologic outcomes.
  
  
  RESULTS
  The control cohort was composed of 100 patients, with 544 screws from T5 to S1. The computer-assisted cohort was composed of 50 patients, with 294 screws from T2 to S1. In the control cohort, 461 of 544 screws (85%) were found completely within their pedicles as compared with 278 of 294 screws (95%) correctly placed in the computer-assisted group (P < 0.0001). All 16 screws incorrectly placed with computer assistance were found 0.1 mm to 2 mm from the pedicle cortex. In the control cohort, 68 screws were found 0.1 mm to 2 mm, 10 screws 2.1 mm to 4 mm, and 5 screws more than 4 mm from the pedicle cortex. Seven patients in the control cohort were surgically retreated because of postoperative neurologic deficits, whereas no patients in the computer-assisted group were surgically retreated.
  
  
  CONCLUSIONS
  Computer assistance can decrease the incidence of incorrectly positioned pedicle screws.
authors.affiliation: Service d'orthop¿edie, H¿opital Sainte-Justine, Universit¿e de Montr¿eal, Canada. lamiot@justine.umontreal.ca
authors.forename: L P
authors.initials: LP
authors.lastname: Amiot
authors.forename: K
authors.initials: K
authors.lastname: Lang
authors.forename: M
authors.initials: M
authors.lastname: Putzier
authors.forename: H
authors.initials: H
authors.lastname: Zippel
authors.forename: H
authors.initials: H
authors.lastname: Labelle
mesh_terms: D001863:Bone Screws; D015331:Cohort Studies; D006801:Humans; D008159:Lumbar Vertebrae / Q000601:surgery; D008279:Magnetic Resonance Imaging; D012086:Reoperation; D015203:Reproducibility of Results; D012447:Sacrum / Q000601:surgery; D013122:Spinal Diseases / Q000175:diagnosis / Q000601:surgery*; D013123:Spinal Fusion / Q000379:methods* / Q000592:standards; D013131:Spine / Q000601:surgery*; D013813:Therapy, Computer-Assisted / Q000379:methods* / Q000592:standards; D013904:Thoracic Vertebrae / Q000601:surgery; D014025:Titanium
chemical_list: D014025:Titanium