Upper Cervical Injuries

Definition

The atlas (C1) and axis (C2) form a unique upper-cervical complex specialised for rotation and support of the skull. Two classic bony injuries here are the Jefferson fracture of C1 and the Hangman’s fracture of C2.

Jefferson Fracture (C1)

A burst fracture of the ring of the atlas caused by an axial load onto the head (e.g. Diving into shallow water), which splays the lateral masses. Stability depends on the transverse ligament: if it is intact the fracture is stable; if disrupted (suggested by lateral-mass overhang > ~7 mm on the open-mouth view) it is unstable. Despite the dramatic radiograph, neurological injury is often absent because the canal is capacious at this level.

Hangman’s Fracture (C2)

A traumatic spondylolisthesis of the axis — bilateral fracture of the pars interarticularis of C2 — from a hyperextension–distraction force (judicial hanging historically; now RTAs). Like the Jefferson fracture, the canal is wide here so cord injury is frequently avoided.

Management

Both are assessed with CT (and MRI for ligamentous/cord concern). Stable injuries are treated with a rigid collar or halo vest; unstable patterns (disrupted transverse ligament, significant displacement or angulation) require surgical stabilisation/fusion. Immobilisation and prevention of secondary injury apply throughout.

Clinical Features

There is upper neck pain and stiffness after axial or hyperextension trauma, often with the patient guarding or supporting the head. Neurological deficit is frequently absent because the spinal canal is capacious at the C1–C2 level, but a deficit or vertebral artery injury must always be sought. Diving into shallow water, falls onto the vertex and high-speed RTAs are the typical mechanisms. Suspicion plus a low threshold for CT is essential, as plain radiographs readily miss these injuries.

Both are often neurologically intact due to a capacious canal.

• Jefferson = axial-load burst of C1; stability depends on the transverse ligament.
• Hangman’s = hyperextension bilateral C2 pars fracture (traumatic spondylolisthesis).
• Wide canal at C1–C2 → cord injury often avoided despite dramatic films.
• Stable → collar/halo; unstable → fusion. CT is the key investigation.