The accuracy and safety of image-guidance system using intraoperative fluoroscopic images: an in vitro feasibility study.

The "virtual fluoroscopy" is a new navigation system that combines image-guided surgery and C-arm fluoroscopy. The purpose of this study was to evaluate the accuracy of this system in the case of pedicle screwing. The angular deviation in the axial and sagittal planes was measured using the bodies of 50 vertebral models. Another type of model was used to evaluate the positional deviation (two dimension and three dimension). The mean angular deviation on the axial plane was 1.3 degrees and that on the sagittal plane was 1.0 degree. The positional deviation was not recognised. This system provides quite accurate information. Using this system, the surgeon can insert surgical instruments, such as pedicle screws, while confirming the real time virtual image on the monitor displaying the surgical field, including the position and direction of the instruments, without being disturbed by his own hands or instruments and without radiation exposure.