Intervertebral discs: nuclear morphology and bursting pressures

Abstract

The morphology of the nucleus pulposus was determined by discography in 78 cadaveric discs and they were classified into the following groups: globular, posterolateral winging, posterolateral hernia, posterior position, irregular, central posterior hernia, and degenerate. Each nucleus was burst with a hydraulic pump and the pressure and site of bursting determined. Globular, posterolateral winging, and irregular nuclei required high pressures to produce failure and this usually occurred by fracture of the vertebral end plates. Posterolateral hernia, central posterior hernia, and degenerate nuclei burst at low pressures in the posterolateral and posterior directions. Increase in intranuclear pressure will not usually produce the types of disc prolapse associated with nerve root damage unless there is a gross abnormality of disc structure.