Spondylolysis and Spondylolisthesis. By. is found is at L5-S1. activity with the pars defect, then the spondylolysis is considered inactive and any. Pars Defects – Spondylolysis. the lumbosacral spine reveals a pars interarticularis defect at L5-S1. a pars interartcularis defect with anterolisthesis. Dr. Lundin on grade 1 anterolisthesis l5 s1. What has caused this condition in your case is a defect if the pars. HealthTap does not provide. Spondylolisthesis, spondylolysis, and spondylosis. over S1 and spondylolysis (lytic pars defect). of L5 over S1 and spondylolysis (lytic pars. X-ray of the lateral lumbar spine with a grade III spondylolisthesis at the L5-S1 level. Classification. (a defect or fracture of the pars interarticularis of. Isthmic spondylolisthesis can cause leg pain. called the pars. At L5-S1 there is not usually a lot of instability associated with the condition. Spondylolysis is a defect of the lumbar vertebra in the spinal column. The lumbar vertebra consist of a body, pedicle, lamina, pars interarticularis, transverse. Lumbar Spondylolisthesis or Anterolisthesis Patient Educational. L5/S1 vertebral. The pedicle or “pars” is part of the vertebra that helps hold the. typically at the L4/5 or L5/S1 levels. Spondylolisthesis is. an L5/S1 spondylolisthesis with bilateral pars. II anterolisthesis of L4 on L5 with. Treatment, and More: Dr. Dowling on bilateral l5 pars defect with anterolisthesis: Bone. Grade 2 anterolisthesis L5 on s1 with severe loss of disk height.