Imaging and biomechanics researches of reconstructing lumbosacral stability after L 5 vertebrectomy via anterolateral approach

Abstract

To investigate the feasibility of anterolateral approach for L 5 vertebral resection, bone grafting, and screw rod fixation by imaging and biomechanics researches. Twenty formalized adult cadavers (12 males and 8 females) were randomly divided into 2 groups; L 5 vertebral resection, bone graft, and screw rod fixation was performed on 10 specimens by using anterolateral approach (experimental group), and on the other 10 specimens by combined anterior and posterior approach. CT scanning and three-dimensional reconstruction were performed in the experimental group; preoperative maximal safe entry angle and depth of screws and intraoperative actual entry angle and depth of screws were measured; the sacral screw position was observed after operation. The biomechanical test was done in 2 groups. Twenty specimens smoothly underwent L 5 excision and reconstruction. CT scan showed that there was no significant difference in maximal safe entry angle and depth of screws between males and females in experimental group before operation ( P>0.05); the maximal safe entry angle and depth were 51.93° and 47.88 mm for anterior screw, and were 37.04° and 46.28 mm for posterior screw. After operation, depth of the sacral anterior and posterior screws were appropriate, which did not pierce into the spinal canal. The biomechanical test results indicated that the flexion, extension, and lateral flexion displacements, and vertical compression stiffness showed no significant difference between 2 groups ( P>0.05). For L 5 lesions not invading posterior column, to use L 5 vertebral resection, bone graft, and screw rod fixation by anterolateral approach is a safe and feasible method to reconstruct lumbosacral stability, with the advantages of no changing posture, less operation time and incision, and prevention of bone graft shift, but effectiveness need further be identified.