A new approach to computer-aided spine surgery: fluoroscopy-based surgical navigation.

A new computer-based navigation system for spinal surgery has been designed. This was achieved by combining intraoperative fluoroscopy-based imaging using conventional C-arm technology with free-hand surgical navigation principles. Modules were developed to automate digital X-ray image registration. This is in contrast to existing computed tomography- (CT) based spinal navigation systems, which require a vertebra-based registration procedure. Cross-referencing of the image intensifier with the surgical object allows the real-time image-interactive navigation of surgical tools based on one single registered X-ray image, with no further image updates. Furthermore, the system allows the acquisition and real-time use of multiple registered images, which provides an advanced multi-directional control (pseudo 3D) during surgical action. Stereotactic instruments and graphical user interfaces for image-interactive transpedicular screw insertion have been developed. A detailed validation of the system was performed in the laboratory setting and throughout an early clinical trial including eight patients in two spine centers. Based on the resulting data, the new technique promises improved accuracy and safety in open and percutaneous spinal surgery.