APPLICATION OF FRAMELESS STEREOTAXY TO PEDICLE SCREW FIXATION OF THE SPINE

Interactive frameless stereotaxy has been successfully applied to intr acranial surgery. It has contributed to the improved localization of d eep-seated brain lesions and has demonstrated a potential for reducing both operative time and morbidity. However, it has not been as effect ively applied to spinal surgery.The authors describe the application o f frameless stereotactic techniques to spinal surgery, specifically pe dicle screw fixation of the lumbosacral spine. Preoperative axial comp uterized tomography (CT) images of the appropriate spinal segments are obtained and loaded onto a high-speed graphics supercomputer workstat ion. Intraoperatively, these images can be linked to the appropriate s pinal anatomy by a sonic localization digitizer device that is interfa ced with the computer workstation. This permits the surgeon to place a pointing device (sonic wand) on any exposed spinal bone landmark in t he operative field and obtain multiplanar reconstructed CT images proj ected in near-real time on the workstation screen. The images can be m anipulated to assist the surgeon in determining the proper entry point for a pedicle screw as well as defining the appropriate trajectory in the axial and sagittal planes. It can also define the correct screw l ength and diameter for each pedicle to be instrumented. The authors ap plied this device to the insertion of 150 screws into the lumbosacral spines of 30 patients. One hundred forty-nine screws were assessed to be satisfactorily placed by postoperative CT and plain film radiograph y. In this report the authors discuss their use of this device in the clinical setting and review their preliminary results of frameless ste reotaxy applied to spinal surgery. On the basis of their findings, the authors conclude that frameless stereotactic technology can be succes sfully applied to spinal surgery.