[Chance's fracture].

Described by Chance (1948) this fracture is induced by a mechanism of flexion distraction (seat belt fracture). The injury is characterized by the following (W.S. Smith, 1969): A disruption of the vertebral body by an horizontal splitting of this formation and neural arches through the pedicles, nor, or a minimum decrease in the anterior height of the involved vertebral body, no forward or lateral displacements of the superior vertebra, location of the disruption between the first and third lumbar vertebra in the majority of cases. Four patterns of Chance's fracture are isolated in this paper: First pattern: The osseous disruption cross the posterior arches, pedicles and vertebra. The fracture is unstable. Second pattern: horizontal fracture involves both pedicles with extension anteriorly through inferior third of the vertebral body (unstable). Third pattern: Chance's fracture with anterior vertebral extension through superior third of vertebra (unstable). Fourth pattern: fracture with anterior horizontal vertebral disruption in the posterior half of the body (stable).