Anatomical parameters of fifth lumbar vertebra in L5-S1 spondylolytic spondylolisthesis from a surgical point of view

We measured the length, width, height, and angles related to both Meyerding grading system and Marchetti-Bartolozzi classification in L5-S1 spondylolytic spondylolisthesis patients to investigate the anatomical characteristics of fifth lumbar pedicles. Seventy patients with L5-S1 spondylolytic spondylolisthesis and general spinal disease were included. Patient attributes, Meyerding grading system and Marchetti-Bartolozzi classification of spondylolisthesis, length, width, height of L4 and L5 pedicle, and the angle between pedicle and vertebral midline were measured. The heights of L5 vertebral body, divided as anterior, mid, and posterior were also measured. The pedicle is elongated and the angle of the pedicle is wider in cases of L5-S1 spondylolysis. Vertebral body shape was more posteriorly wedged in L5-S1 spondylolysis. Pedicles were more narrow and shorter in L5-S1 spondylolysis. In L5-S1 spondylolytic spondylolisthesis, a longer screw is suitable for insertion of L5 pedicle and the screw should be inserted more medially compared to patients without spondylolysis.