Classification Description Notes
Type 1 Fracture through posterior arch Stable. Hyperextension injury
Type 2 Fracture through anterior arch Stable. Hyper flexion injury
Type 3 Bilateral posterior with uni- or bilateral anterior arch Stability depends on integrity of the transverse ligament. Axial load injury. “Jefferson Burst”.
Type 4 Fracture through the lateral mass Unstable. Axial load and rotation injury
Type 5 Transverse fracture through anterior arch Unstable. Avulsion of longus coli or atlantoaxial ligament



Dreizin, D., et al. (2014). “Multidetector CT of blunt cervical spine trauma in adults.” Radiographics 34(7): 1842-1865.

Bransford, R., et al. (2009). “Unilateral C-1 lateral mass sagittal split fracture: an unstable Jefferson fracture variant.” J Neurosurg Spine 10(5): 466-473.

Gehweiler JA Jr, et al. (1976). “Fractures of the atlas vertebra.” Skeletal Radiol 1(2):97–102.