The vertebral canals in lumbar disc disease.

The sagittal dimensions of the five lumbar vertebral canals tend to be more shallow in patients operated for lumbar radiculopathy than in a group of controls. The more frequent occurrence of radiculopathy in patients with small canals can be explained by the requirement for only a small protrusion of intervertebral disc, or any other structural abnormality, to impinge the nerve. The sagittal diameter can be obtained easily from the lateral roentgenogram and, therefore, requires no invasive or expensive tests. This measurement can be quite helpful in interpreting myelographic defects and in planning and doing operations on patients with radiculopathy.