Chance fractures occur as a result of acute hyper-flexion and distraction injury to the spine around the thoracolumbar area, especially T11 to L2. This is due to the relative immobility of the thoracic spine as compared to the lumbar spine.Common mechanism is MVA due to incorrectly worn lap seat-belt. It is also less commonly caused by a fall from a height.

This is an unstable injury but neurological complications are infrequent. However, these injuries often have a high association with intra-abdominal and retroperitoneal injuries (up to 50-60%).