Feasibility Analysis Of A New Mimics Based Approach To Locate Insertion Points In The L5 Pedicle

Objective: In the clinical practice of lumbar pedicle screw implantation,due to the lack of a typical hercules ridge structure in L5,it is usually necessary to enlarge the surgical incision or excessively pull the soft tissues such as the muscles and fascia of the lower back in order to find the insertion point.Although the transverse process,intervertebral joint and other anatomical sites can be used to determine screw placement points,the excessive exposure of these anatomical sites greatly increases the risk of bleeding and the operation time.In addition,in cases of severe lumbar degenerative disease,the difficulty in identifying the above anatomical markers further increases the difficulty of operation.For this reason,we used the intersection point of the horizontal line at the root of the spinous process and the vertical line at the outer edge of the lamina as the L5 insertion point,and performed pedicle screw internal fixation to achieve good clinical results.The purpose of this study is to use mimics to reconstruct L5 in 3d,simulate screw placement with newly defined screw placement points,collect relevant screw placement data as a reference,and discuss the safety,accuracy and feasibility of the newly defined screw placement points in L5 pedicle screw based on clinical practice.Methods: Randomly selected 50 cases of normal lumbar spine three-dimensional CT imaging raw material,import it Mimics V21.0 in reconstruction of L5three-dimensional simulation image,on the 3 d image positioning new nailing point and simulation,nailing observation is correct in pedicle screw,measuring the new definition into nail points with pedicle axis position relations with neighbours,measuring the transpedicular screw on the surface of the depth and the sagittal and coronary nailing Angle and distance between pin the tail on both sides.A total of 100 patients who planned to undergo lumbar surgery and needed L5 screw fixation were randomly selected clinically.In the experimental group,50 patients underwent L5 pedicle screw internal fixation at the new registration point.Pedicle screw was implanted according to the Angle of preoperative simulated screw placement measurement.The 50 patients in the control group received traditional screw placement,and the same c-arm fluoroscopy ensured the safety and accuracy of screwplacement.Postoperative screw placement time,blood loss,postoperative pain visual score,screw placement accuracy,repeat screw placement rate,intraoperative fluoroscopy time,length of stay and postoperative complications were compared between the two groups.Results:In this study,it was found that even in patients with severe lumbar degenerative disease,it was difficult to identify anatomical marks such as facet joints and transverse processes,because the degenerative changes of spinous process and lamina were small and the anatomical marks were relatively fixed.Therefore,it provided a new method for pedicle screw implantation in patients with severe L5 degenerative disease.The newly positioned screw placement point was located on the medial side of 3.58±1.41 mm of the central axis of the vertebral pedicle.The simulated screw placement depth was 43.28±3.36 mm,the sagittal plane Angle was 14.48±3.34°,and the transverse section Angle was 13.84±2.71°.The center of screw track was located at 1.33±0.55 mm on the medial axis of the vertebral pedicle,1.24±0.63 mm on the upper side,and the distance between the screw ends was 45.46±3.86 mm.During clinical surgery,100 L5 pedicle screws were implanted by the new positioning method.96(96%)screws were accurately and safely located in the vertebral pedicle,while 4(4%)screw placement was not effective.A total of 100 L5 pedicle screws were implanted by the traditional screw placement method.Ninety-four(94%)screws were located in the vertebral pedicle accurately and safely,while six(6%)screws were poorly placed.The two groups of patients did not show the nerve root injury and other adverse complications.Compared with the two groups of patients,the new positioning method was better than the traditional one in screw placement time,screw placement blood loss,postoperative pain visual score,screw placement accuracy,repeat screw placement rate,intraoperative fluoroscopy time and length of stay,but there was no significant difference in postoperative complications.Conclusion:Because the degree of degeneration of spinous process and lamina is small and the anatomical site is relatively stable,the screw placement problem in patients with severe lumbar degenerative disease and other typical anatomical markers are not easily recognized has been solved.At new nail pedicle axis slightly inside,without too much exposure intervertebral joint capsule and transverse process such asanatomy,reducing the excessive force,muscle and fascia in nailing time,blood loss,postoperative pain visual grading nailing,repetition and the accuracy rate of nailing,intraoperative fluoroscopy time,hospitalization days were superior to the traditional aspects such as nailing method.Therefore,it is a safe and feasible positioning method to use the intersection of the horizontal line at the root above the spinous process and the vertical line at the outer edge of the lamina as the insertion point of L5 pedicle screw.