The sternal-rib complex. A possible fourth column in thoracic spine fractures.

Two cases are described in which displaced sternal fractures were associated with thoracic spine fractures of minimal, initial displacement. Nonoperative, expectant treatment led to significant kyphotic deformity. It is postulated that the sternum and ribs represent a fourth column of structural thoracic spine support. An overriding, displaced sternal fracture is a marker for a severe flexion-distraction unstable thoracic spine injury with a propensity for deformity.