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

Study Design. A comparative study on the position of pediclescrews 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.