The radiologic assessment of post-traumatic vertebral stability

Abstract

The stability of the vertebral column depends upon the integrity of the bones, ligaments, and joints. The vertebral column can be divided into three distinct anatomic zones: anterior, middle, and posterior. Disruption of any single zone does not produce instability. Disruption of two contiguous zones will, however, significantly decrease the load-carrying capability of the spine and result in instability. Five radiographic signs indicative of vertebral instability have been identified: (1) displacement implies injury to major ligamentous and articular structures; (2) a wide interlaminar space implies injury to the posterior ligamentous structures and the facet joints; (3) wide facet joints imply injury to the posterior ligamentous structures; (4) a disrupted posterior vertebral body line implies burst injury with disruption of anterior bony and posterior ligamentous structures; (5) a wide vertebral canal implies injury to the entire vertebra in the sagittal plane. Each of these signs indicates disruption of a major skeletal, ligamentous, or articular structure and the presence of only one is sufficient to establish a diagnosis of instability. These conclusions are based upon a study of 138 injuries observed in 125 patients.