Navigation at the spine.

Computer aided and computer navigated operative techniques have been used for the first time in neurosurgery and surgery of the spine. For computer aided surgery of the spine there are currently two different methods: CT-based and C-arm based techniques. The advantage of the CT-based technique is its accuracy especially in difficult anatomical regions like the cervical and upper thoracic spine, and the possibility of preoperative planning. The advantage of C-arm navigation is the broad intraoperative availability with the disadvantage of limited image quality in some regions of the spine eg, the upper thoracic spine. This last disadvantage has been dramatically improved by introducing 3-D C-arm navigation (ISO C 3-D, Siemens, GER). Generally, all methods enhance the precision of pedicle screw insertion. Clinical as well as experimental studies show an exact pedicle screw position using the computer navigated techniques in over 90% of cases. C-arm based navigational techniques are being constantly improved and the future will be CT-like images with instant intraoperative availability.