Influence of flexion-extension motion of lumbar spine on lumbosacral dural sac. An experimental study

To analyze the effects of flexion-extension motion of lumbar spine on the position and shape of lumbosacral dural sac, 10 flexion/extension lateral myelograms of cadaver specimens of normal lumbar spine were measured. The results showed that moving from flexion to extension both sagittal diameter and length of the dural sac decreased significantly, the dural sac moved caudally, and the sagittal diameter of the anterior epidural space decreased in the mid-vertebral level but increased in the intervertebral level. The dynamic changes of the dural sac and their influence factors and clinical relevance were discussed.