A novel pedicle screw placement technique with reference to the percutaneous anatomic landmarks of the highest point of the spinous process

Pedicle screw placement is technically demanding and involves radiation exposure in thoracic and lumbar spine. A large number of rays have a serious impact on both patients and surgeon. The purpose of our study was to introduce a new free-hand pedicle screw placement which can reduce the exposure as compared with the traditional posterior open method. The sagittal screw angle between the vertebral upper end plate and percutaneous anatomic landmarks of the spinous process was measured from MR images before the operation. Total 126 cases of single-segment thoracolumbar fractures without neurologic injury underwent pedicle screw fixation via two different approaches (i.e., a new free-hand pedicle screw placement and the traditional posterior open method). In the new free-hand technique group, without exposure of the spinal process, the pedicle screw was inserted perpendicularly to the percutaneous anatomic landmarks of the highest point of spinous process according to the angle measured from the MRI before operation. In the conventional technique group, we perform a posterior midline incision at the target segment and striped the paraspinal muscle along the spinous process and the vertebral lamina, and then the intraoperative fluoroscopic guidance was used to determine sagittal screw angle and transverse screw angle. The angulation between the vertebral upper end plate and the percutaneous anatomic landmarks of the spinous process from MRI was close to 90 degrees. Screw placement accuracy, operative time, blood loss, postoperative drainage, postoperative hospitalization time, and radiation exposure time of the two methods were compared. There was no statistical difference in the placement accuracy of the new free-hand technique and the conventional technique group (P=0.741). The operative time, blood loss, the postoperative hospitalization time, postoperative drainage and the frequency of intraoperation of the two methods were also compared, there were significant differences between the new free-hand group and the conventional group. This novel percutaneous pedicle screw placement technique referring to the anatomic landmarks of the spinous process is an accurate, reliable and safe technique for treating simple fracture in the thoracic or lumbar spine. In this novel screw placement procedure, there is less radiation exposure for surgeons and much lower fluoroscopy exposure for patients.