Stenosis of the lumbar spine in spondylolisthesis.

There are three factors which determine the volume of the spinal canal, its lateral recesses and the intervertebral canals; the developmental size; the level cephalad and caudad of the vertebral column; the multiple acquired conditions which may cause encroachment. The causes of narrowing in spondylolisthesis are characteristic of each type. Three common groups are mentioned, congenital, isthmic and degenerative and the nature of obstruction and its appropriate treatment is described in each case.