History
This adult male patient was involved in a car accident.  He struck his head on the windshield and was then thrown into hyperextension.

Discussion
Hangman’s Fracture (Traumatic spondylolisthesis). Fractures of the neural arch of the axis are one of the most common injuries of the cervical spine. Up to 40% of axis fractures are hangman’s fractures.1  They are usually the results of automobile accidents in which there is abrupt deceleration from a high speed, though the fracture occurs during hyperextension.  The distribution of the fracture is similar to that resulting from judicial hanging.  This has prompted the term hangman’s fracture.  This is actually a misnomer, since the hangman does not receive the fracture.  It should more accurately be called the hangee’s fracture.1
The fracture occurs as a bilateral disruption through the pedicles of the axis, sometimes referred to as the pars interarticularis.  The fracture lines are best seen on CT or the lateral view just anterior to the inferior facet, usually in association with anterior displacement of C2 upon C3.  This displacement is usually persistent following osseous union, a sign of previous injury, which should be recognized.  Occasionally the axis body will be flexed and distracted superiorly.  Prevertebral hemorrhage is common, increasing the retropharyngeal interspace that may compromise the adjacent airway.  Up to 25% have an accompanying fracture, usually of the atlas.2  An avulsion of the anterior–inferior corner of the vertebral body (teardrop fracture) often occurs simultaneously. 
There is a surprising lack of neurologic findings in fractures of the neural arch of the axis due to the large spinal canal at this level.  Extension of the fracture into the transverse foramen may precipitate vertebral artery injury.1

Dr. Terry R. Yochum is a second generation chiropractor and a Cum Laude Graduate of National College of Chiropractic, where he subsequently completed his radiology residency. He is currently Director of the Rocky Mountain Chiropractic Radiological Center in Denver, Colorado, and Adjunct Professor of Radiology at the Southern California University of Health Sciences, as well as an instructor of skeletal radiology at the University of Colorado Schoolof Medicine, Denver, CO. Dr. Yochum can be reached at 1-303-940-9400 or by e-mail at This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

Dr. Chad Maola is a 1990 Magna Cum Laude Graduate of National College of Chiropractic. Dr. Maola is available for post-graduate seminars. He may be reached at 1-727-433-0153 or by email at This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

References
1. Yochum TR, Rowe LJ:  Essentials of Skeletal Radiology, 3rd ed., Lippincott, Williams & Wilkins, Baltimore, Maryland, 2005.
2. Resnick D: Diagnosis of Bone and Joint Disorders, 2nd ed., W B Saunders, 1988.