Jefferson Fracture

Axial CT image shows double fractures of the anterior arch and a single fracture of the posterior arch of atlas (C1) (arrows) with mild displacement.

Facts:

• C1 fracture believed to be due to compression causing fracture of the arch of atlas
• Often in combination with avulsion of the transverse ligament of the C1
• Simultaneous injuries to other C spine are common
• Three types: fracture of only anterior arch (type 1), fracture of only posterior arch (type 2), and fractures of both anterior and posterior arches (type 3)
• Type 3 fracture is unstable
• Fractures rare in children, but one needs to know that anterior synchondroses fuse at age 7, posterior at age 4.

Imaging Findings

• MDCT is imaging modality of choice, able to demonstrate fracture lines and degree of displacement
• On radiograph, displacement of the lateral masses may be seen on the odontoid view.
• Mimicker = failure of fusion of the vertebral arch, this pseudo-fracture lines are less sharply defined and/or sclerotic.

References:

1. Imhof H, et al. Spinal Imaging, 2008.

2. Atlas Frx / Jefferson Fracture in Wheeless' Textbook of Orthopedics