Which fracture is known as a Jefferson fracture, resulting from vertical compression of the atlas?

• A. Clay Shoveler's Fracture
• B. Burst Fracture
• C. Hangman's Fracture
• D. Jefferson Fracture

Answer: (D)

A Jefferson fracture is an atlas fracture caused by vertical (axial) compression. When a strong vertical load hits the head, the ring of the first cervical vertebra (the atlas) can burst, breaking both the anterior and posterior arches. As the ring splits, the lateral masses are pushed outward, leading to lateral widening of the atlas on imaging. This mechanism—bursting of the C1 ring from vertical compression—is what distinguishes a Jefferson fracture from other cervical injuries. For example, a Hangman’s fracture is a fracture of the C2 pars interarticularis from hyperextension, a Clay Shoveler’s fracture is an avulsion of the spinous process, and a burst fracture generally involves a vertebral body (not the atlas) from high-energy axial load.