IN-VITRO SIMULATION - EARLY RESULTS OF STEREOTAXY FOR PEDICLE SCREW PLACEMENT

Study Design. Frameless stereotaxy with doppler ultrasound and three d imensional computer model registration is assessed in vitro for pedicl e screw placement. Objective. To identify feasibility of pedicle screw navigation and placement using this technology. Summary of Background Data. Inaccurate pedicle screw placement can lead to neurovascular in jury or suboptimal fixation. Present techniques in pedicle screw place ment involve only confirmation of hole orientation. Method. Forty-four pedicle screws were placed in lumbosacral models and cadaver specimen s. Accuracy was assessed with a computed tomography scan and vertebral cross sectioning. Results. All screws were intrapedicular. Accuracy o f anterior cortical fixation was 1.5 mm, with a range of 2.5 mm. Concl usion. In vitro frameless stereotaxy is accurate for pedicle screw pla cement. This technology adds a component of navigation to pedicle scre w placement.