Study design: An international, multicenter, prospective, postmarketing clinical registry to record the accuracy of pedicle screw placement, using the O-arm Complete Multidimensional Surgical Imaging System with StealthStation Navigation.
Objective: To evaluate the accuracy of pedicle screw placement in common neurosurgical practice and assess the patient's radiation exposure.
Summary of background data: Several imaging techniques have been used to increase accurate pedicle screw placement. The O-arm 3-dimensional (3D) imaging (Medtronic Navigation, Louisville, CO), an intraoperative computed tomographic (CT) scan, combined with an existing navigation system was reported to further increase accuracy of screw placement, especially because an intraoperative 3D scan provides information for screw adjustment before wound closure.
Methods: Patients already planned for instrumented spinal surgery were operated while using the O-arm as imaging device and the StealthStation Navigation (Medtronic Navigation, Louisville, CO) as navigation tool. At the end of all pedicle screw insertions, the placement was classified according to a validated method. The accuracy of pedicle screw placement based on the intraoperative 3D scan and the surgeon's perception of correct screw placement were assessed as well as the radiation doses the patient received during the entire procedure.
Results: During a 16-month period, a total of 1922 screws in 353 patients were evaluated. In 97.5%, the screws were correctly placed. Only 2.5% of the screws were considered as misplaced, and 1.8% of the screws were revised during the same procedure. When the surgeon perceived the screws to be correctly placed, the CT scan verified his assessment in 98.5% of the cases. The mean radiation dose was comparable with half the dose of a 64 multislice CT scan.
Conclusion: The use of the O-arm in combination with a navigation system increases the accuracy of pedicle screw placement. The accuracy of the surgeon's perception and the need to limit the radiation dose for the patient justify an additional CT scan only after careful assessment of the potential additional value.