From the Guidelines
A Chance fracture is a specific type of spinal injury that involves a horizontal splitting of the vertebra caused by flexion forces, typically occurring in the thoracolumbar spine. This type of fracture is often associated with lap belt injuries during motor vehicle accidents and extends through all three columns of the spine, starting at the posterior elements and progressing forward through the vertebral body 1. The diagnosis of a Chance fracture can be made using CT imaging, which is the gold standard for identifying fractures of the thoracolumbar spine, with a reported sensitivity of 94% to 100% 1. Key characteristics of a Chance fracture include:
- Horizontal splitting of the vertebra
- Typically occurs in the thoracolumbar spine, most commonly at the T12-L2 levels
- Often associated with lap belt injuries during motor vehicle accidents
- Extends through all three columns of the spine
- Patients may present with back pain and associated intra-abdominal injuries in up to 50% of cases
- Neurological deficits are possible but less common than with other spinal fractures
- Treatment depends on stability and neurological status, ranging from conservative management with bracing for stable fractures to surgical stabilization for unstable fractures or those with neurological compromise. CT imaging of the thoracolumbar spine is excellent for delineating soft-tissue injuries of the chest, abdomen, and pelvic region that often accompany spinal fractures, and obtaining sagittal and coronal spine images from existing chest, abdomen, and pelvis CT data is a recommended practice that is both effective and radiation dose sparing 1.
From the Research
Definition of Chance Fracture
A Chance fracture, also known as a "seatbelt fracture," is an unstable spinal injury that usually occurs at the thoracolumbar junction 2. It is characterized by a disruption of the vertebral body by an horizontal splitting of this formation and neural arches through the pedicles, with no forward or lateral displacements of the superior vertebra 3.
Mechanism of Injury
The mechanism of injury for a Chance fracture is typically a flexion distraction, which can occur in various scenarios, including:
- Car crashes, particularly head-on collisions while wearing a lap seat belt without a shoulder strap 4, 5
- Falls from a height, which can cause a flexion distraction injury even in unbelted persons 5
- Other axial loading mechanisms, which can be atypical, such as a 30-foot vertical fall 2
Patterns of Chance Fracture
Four patterns of Chance's fracture have been identified:
- First pattern: The osseous disruption crosses the posterior arches, pedicles, and vertebra, resulting in an unstable fracture 3
- Second pattern: Horizontal fracture involves both pedicles with extension anteriorly through the inferior third of the vertebral body, also unstable 3
- Third pattern: Chance's fracture with anterior vertebral extension through the superior third of the vertebra, unstable 3
- Fourth pattern: Fracture with anterior horizontal vertebral disruption in the posterior half of the body, stable 3
Complications and Treatment
Complications of a Chance fracture can include spinal cord injury, neurological deficits, and long-term functional impairment if not promptly identified and treated 2. Treatment typically involves surgical stabilization, such as pedicle screw fixation and laminectomy, to prevent long-term complications 2, 4, 6.