Image-guided spine surgery

Intra-operative computer assistance, by means of image interactive visualis ation of surgical action, is a rather novel aspect of spinal surgery. The u nderlying concept is to incorporate preoperative 3D image data, such as com puted tomography (CT) or MRI into the intra-operative procedure. This is ac hieved by visualising the actual position and orientation of surgical instr uments relative to the operated anatomy on a computer monitor. The aim is t o allow for a more precise and safer intervention. In principle, each navig ation system consists of three components: the image data-set; the bony ana tomy to be operated on; and a navigator, which links the two. Most research effort so far has been spent on developing image-guided insertion of trans pedicular screws in the thoracolumbar and lumbosacral spine. Several naviga tional systems for these applications have successfully completed the step from the laboratory into routine clinical use and first promising results o f their performance have been published. This paper explains the functional basics of such systems in general and describes those navigation tools tha t are available for use in spinal surgery. In addition, an alternative, rec ently-developed concept incorporating intra-operative imaging is presented.