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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

 

 

 

 

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