An endoscopic pedicle probe: preliminary development

Insertion of pedicle screws in the thoracolumbar spine can be challenging. Incorrect placement can lead to a failure of fusion or to significant neurologic morbidity. Recently, techniques utilizing intraoperative monitoring and stereotaxis have been developed to achieve proper screw placement. While these techniques may be accurate, they are expensive and may require additional operating room personnel. We have developed an endoscopic pedicle probe for placement of pedicle screws that may overcome some of these limitations. A small 1.2 mm endoscope was adapted to fit within a hollow pedicle probe. Irrigation was provided via a separate channel within the endoscope. Images from the probe were displayed both on a monitor screen and on a heads up display. The endoscopic probe was used to probe 36 sawbone and 22 cadaver thoracolumbar pedicles. After cannulation each specimen was examined to assess nonvisualized pedicle perforation. In sawbones, perforation was visualized endoscopically in 3 pedicles (8%) with no further perforations found on later direct examination. In cadavers the cortical cancellous interface was adequately visualized and no perforations occurred. These preliminary results suggest that the endoscopic probe may have utility in the placement of thoracolumbar pedicle screws.