What does a chance/lap belt/slice fracture typically involve?

A chance fracture, also known as a lap belt fracture or slice fracture, typically involves a specific mechanism of injury often associated with automobile accidents where a seatbelt is worn improperly. The defining characteristic of this type of fracture is the distraction of the middle column of the spine. This is due to a flexion-distraction mechanism where the vertebral body is subjected to forces that lead to a fracture that can affect the anterior and posterior elements of the vertebra.

In this type of injury, the middle column, which consists of the posterior longitudinal ligament, the intervertebral disc, and the anterior half of the vertebral body, is compromised. This results in a fracture typically characterized by a horizontal split through the vertebral body and can extend through the pedicles or facets.

This involvement can lead to significant instability, making it critical to identify and treat appropriately. Understanding the characteristics of chance fractures helps clinicians recognize the extent of injury and address potential complications such as spinal instability or neurologic deficits.