Traumatic spondylolisthesis occurs due to forced hyperextension with an axial loading component, with or without rebound hyperflexion.  The most common mechanism of injury is an MVC.  Other mechanisms include diving accidents and falls. 

     There are no specific physical exam findings.  Posterior tenderness over the C2 spinous process is expected.  Facial trauma in the appropriate setting indicates high-energy impact and should raise the index of suspicion for traumatic spondylolisthesis.  Deficits on neurologic exam are more likely due to associated head injury or vertebral artery injury than to damage to the spinal cord since the width of the canal at C2 and the additional space afforded by the pedicle fractures make spinal cord injury rare.