Learning Radiology xray montage
Chance Fracture

   Originally most often caused by seat belts as hyperflexion injuries in automobile accidents

o       With lap belts, it is now seen more often with falls

·         Seat belt injuries usually involve the lower thoracic and upper to mid lumbar spine (L1 and L2 most commonly)

·         Chance fractures are hyperflexion injuries in which there is distraction of the  posterior elements and impaction of the anterior components of the spine

o       Compression component from hyperflexion is usually minor compared to distraction component

·         Clinical findings

o       Back pain is the most common symptom

o       Ecchymosis of anterior abdominal wall should raise suspicion for the presence of this kind of fracture

o       Up to 50% of individuals with Chance fractures may also have serious blunt injury to internal organs

§         Injuries involve primarily the pancreas, duodenum and mesentery

§         The same mechanism of injury may not produce a fracture in children but may still be associated with intestinal and urinary bladder injuries

o       Since the spinal cord ends at T12-L1, injuries to cord are infrequent but the spinal nerves may be injured resulting in bowel and bladder signs

§         Those with a kyphosis of less than 15° have a better neurologic prognosis

o       Mortality is the result of associated internal injuries

·         Imaging findings

o       CT is the most sensitive study although conventional radiographs are usually obtained first

o       Horizontal fracture through the spinous process, laminae, pedicles and vertebral body

o       Vertebral body component may be less prominent than the distraction fractures of the posterior elements which are always present

§         Vertebral body component may not be visible

Chance Fracture. Reformatted sagittal CT of the lower thoracic spine demonstrates a horizontal fracture through the spinous process and pedicles (yellow arrow) and a compression fracture of the vertebral body (red arrow) characteristic of the hyperflexion distraction-impaction injury associated with lap seat belt injuries and falls.

For a photo of the same image without the arrows, click here



o       There may be associated soft tissue swelling

o       Open pedicle sign – lucency on the medial aspects of the pedicles

o       Posterior ligamentous complex tears

§         Up to 50% have injuries to

·         Interspinous ligament

·         Ligamentum flavum

·         Facet capsule

·         Posterior annulus

·         Thoracodorsal fascia

·         Treatment

o       Most Chance fractures are managed with immobilization

o       Instability is frequently associated with a kyphosis of 20° or more and a kyphosis of 30° or more usually requires internal stabilization

o       Main treatment for unstable fractures is surgical fixation with spinal canal decompression