Study Design. A prospective interventional case-series study plus a retrospective analysis of historical patients for comparison of data.
Objective. To evaluate workflow, feasibility, and clinical outcome of navigated stabilization procedures with data acquisition by intraoperative computed tomography.
Summary of Background Data. Routine fluoroscopy to assess pedicle screw placement is not consistently reliable. Our hypothesis was that image-guided spinal navigation using an intraoperative CT-scanner can improve the safety and precision of spinal stabilization surgery.
Methods. CT data of 94 patients (thoracolumbar [n = 66], C1/2 [n = 12], cervicothoracic instability [n = 16]) were acquired after positioning the patient in the final surgical position. A sliding gantry 40-slice CT was used for image acquisition. Data were imported to a frameless infrared-based neuronavigation workstation. Intraoperative CT was obtained to assess the accuracy of instrumentation and, if necessary, the extent of decompression. All patients were clinically evaluated by Odom-criteria after surgery and after 3 months.
Results. Computed accuracy of the navigation system reached <2 mm (0.95 ± 0.3 mm) in all cases. Additional time necessary for the preoperative image acquisition including data transfer was 14 ± 5 minutes. The duration of interrupting the surgical process for iCT until resumption of surgery was 9 ± 2.5 minutes. Control-iCT revealed incorrect screw position ≥2 mm without persistent neurologic or vascular damage in 20/414 screws (4.8%) leading to immediate correction of 10 screws (2.4%). Control-iCT changed the course of surgery in 8 cases (8.5% of all patients). The overall revision rate was 8.5% (4 wound revisions, 2 CSF fistulas, and 2 epidural hematomas). There was no reoperation due to implant malposition. According to Odom-criteria all patients experienced a clinical improvement. A retrospective analysis of 182 patients with navigated thoracolumbar transpedicular stabilizations in the preiCT era revealed an overall revision rate of 10.4% with 4.4% of patients requiring screw revision.
Conclusion. Intraoperative CT in combination with neuronavigation provides high accuracy of screw placement and thus safety for patients undergoing spinal stabilization. Reoperations due to implant malpositions could be completely avoided. The system can be installed into a pre-existing operating environment without need for special surgical instruments. The procedure is rapid and easy to perform without restricted access to the patient and—by replacing pre- and postoperative imaging—is not associated with an additional exposure to radiation. Multidisciplinary use increases utilization of the system and thus improves cost-efficiency relation.
A prospective study to evaluate navigated stabilizations of the whole spine in combination with intraoperative computed tomography. We found high accuracy of screw placement (immediate repositioning of 2.4%), immediate detection of intraoperative complications and no reoperation due to malposition. Multidisciplinary use increases utilization of the system and improves cost-efficiency relation.
From the *Department of Neurosurgery, and †Institute of Clinical Radiology, Klinikum Grosshadern, Ludwig-Maximilians-University, Munich, Germany.
Acknowledgment date: February 3, 2009. Revision date: April 30, 2009. Acceptance date: May 4, 2009.
The device(s)/drug(s) is/are FDA-approved or approved by corresponding national agency for this indication.
No funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.
Supported by BrainLAB, Feldkirchen, Germany and Siemens Healthcare, Forchheim, Germany and Trumpf, Puchheim, Germany.
Address correspondence and reprint requests to Stefan Zausinger, MD, Department of Neurosurgery, Ludwig-Maximilians-Universität, Klinikum Grosshadern, Marchioninistr 15, 81377 Munich, Germany; E-mail: Stefan.Zausinger@med.uni-muenchen.de