Comparative results between conventional and computer-assisted pedicle screw installation in the thoracic, lumbar, and sacral spine

Spine (Phila Pa 1976). 2000 Mar 1;25(5):606-14. doi: 10.1097/00007632-200003010-00012.


Study design: A comparative study on the position of pedicle screws in patients treated surgically with and without computer assistance.

Objectives: To evaluate the accuracy of computer-assisted pedicle screw installation, and to evaluate its clinical benefit as compared with conventional pedicle screw installation techniques.

Summary of background data: 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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bone Screws*
  • Cohort Studies
  • Humans
  • Lumbar Vertebrae / surgery
  • Magnetic Resonance Imaging
  • Reoperation
  • Reproducibility of Results
  • Sacrum / surgery
  • Spinal Diseases / diagnosis
  • Spinal Diseases / surgery*
  • Spinal Fusion / methods*
  • Spinal Fusion / standards
  • Spine / surgery*
  • Therapy, Computer-Assisted / methods*
  • Therapy, Computer-Assisted / standards
  • Thoracic Vertebrae / surgery
  • Titanium


  • Titanium