Fracture of the posterior margin of a lumbar vertebral body.

Using computed tomography, we studied twenty-nine patients who had thirty-one fractures of the posterior margin of a vertebra in the lumbar spine. Based on our findings, these fractures were classified morphologically into three types: a simple separation of the entire margin; an avulsion fracture of some of the substance of the vertebral body, including the margin; and a more localized fracture. In this series, twenty-two of the thirty-one fractures were associated with a defect involving the affected end-plate. This fact suggests that the pathogenesis of these fractures may be the fragility of the end-plate.