Objective: Biplanar fluoroscopic imaging linked to a computer-driven mechanical end-effector is under development as a targeting system for spinal surgery. This technology has the potential to enhance standard intraoperative fluoroscopic information for localization of the pedicle entry point and trajectory, and it may be an effective alternative to the computed tomography-based image-guided system (IGS) in pedicle screw placement. A preclinical study to assess the accuracy and time efficiency of this system versus a conventional IGS was conducted.
Methods: Pedicle screw placement was performed in six cadavers from T1 to S1 levels using the ViewPoint IGS (Picker International, Inc., Cleveland, OH) on one side versus the Fluorotactic guidance system (Z-Kat, Inc., Miami, FL) on the other side. Of 216 possible pedicles, 208 were instrumented; 8 pedicle diameters were too small or were not adequately imaged. Postinsertion, each pedicle was assessed for the presence and location of cortical perforation using computed tomographic scanning and direct visualization.
Results: The number of successful screw placements was 89 (87.3%) of 102 for IGS and 87 (82.1 %) of 106 for the Fluorotactic guidance system, respectively. The mean time to register and operate on one level using the Fluorotactic guidance system was 14:34 minutes (minutes:seconds), compared with 6:50 minutes using the IGS. The average fluoroscope time was 4.6 seconds per pedicle.
Conclusion: Our data indicate that this first-generation fluoroscopy-based targeting system can significantly assist the surgeon in pedicle screw placement. The overall accuracy is comparable to an IGS, especially in the region of T9-L5. A second-generation system with a faster end-effector and user-friendly interface should significantly reduce the operating and fluoroscope time.