Clinical evaluation of a system for precision enhancement in spine surgery

Most techniques in segmental spinal fixation surgery rely on the identification of predefined targets with the help of anatomical landmarks and on intraoperative use of image intensifiers. However, because there is no direct link between the image information, the accessible spinal anatomy, and the action of surgical instruments several potential problems and possible complications are still involved. A novel system for spinal surgery has been designed allowing for the real-time, intraoperative localization of surgical instruments in medical images. In practice this was achieved by combining image-guided stereotaxis with advanced optoelectronic position sensing techniques. Modules were developed for image data processing, surgical planning and simulation, and various intraoperative procedures. A detailed validation of the system was performed indicating an overall accuracy to be better than the slice distance of the spinal image used. In an in-vitro setting 20 pilot holes for pedicle screws were prepared in human cadaveric lumbar spines. An analysis in 77 histological cuts showed an ideal location in 70 and only minor cortex engagement in seven sections. In vivo the system has been successfully applied in three posterior low lumbar stabilizations with overall 15 transpedicular screws. RELEVANCE--:This article focuses on the clinical evaluation of a computer-assisted surgery system and its application to the operating theatre for transpedicular fixation of the spine. The given approach effectively keeps the surgeon 'in the loop' and requires only minor modifications of the established surgical techniques and associated instruments. The results of this study indicate that advanced computer-assisted techniques may significantly improve the accuracy and safety of surgical interventions of the spine. The proposed technique may in future be adapted to other applications in orthopaedic surgery.