Unstable wedge fracture of C7 (hyperflexion injury)

Case contributed by Bruno Di Muzio


Motor vehicle accident.

Patient Data

Age: 18 years
Gender: Male

CT Cervical Spine


Mildly comminuted fracture of the right occipital condyle with 5 mm medial displacement, slightly narrowing the foramen magnum. No convincing extra-axial hematoma. C7 superior endplate fracture with 20% height loss, 2 mm anterior displacement of the fracture fragment. No extension into the posterior vertebral body or posterior elements. The spinal canal remains capacious. Cervical spine alignment is normal. Right first rib neck fracture noted. Tiny left apical pneumothorax.

MRI Cervical Spine (trauma protocol)


There is a comminuted avulsed fracture involving the right occipital condyle with medial fragment displacement (alar ligament avulsed fracture), which does not cause significant stenosis of the foramen magnum but mildly pushes against the V3/V4 transition of the right vertebral artery. Both vertebral arteries demonstrate normal flow-void though. 

Compression fracture causing anterior wedging of the C7 vertebral body with height loss in about 20% but no associated retropulsion. There is disruption of the flavum ligament at C6/7. Increased signal suggesting avulsion of the nuchal ligament from its insertion on the C7 spinous process and a mildly increased signal of the C6/7 interspinous ligament suggesting some distraction. The anterior longitudinal ligament appears redundant at the level of C6/7 with no tear identified; some edema is noted in the prevertebral soft tissues at this level. The remainder of the vertebral bodies has normal height, bone marrow signal, and alignment. The cord is normal in the signal. The canal and neural exit foramina are capacious, with no high-grade stenosis. Limited views of the posterior fossa are unremarkable. 

Yellow arrow showing anterior wedge fracture of C7, star showing flavum ligament rupture, and blue arrow showing mild widening of the interspinous space, which has been demonstrated with increased signal suggesting some degree of sprain. 

Case Discussion

This case demonstrates hyperflexion injury of the cervical spine characterized by an anterior wedge fracture of C7 that is unstable given the associated posterior column ligamentous tear and sprain. Also, a right occipital condyle comminuted fracture/avulsion injury of the alar ligament attachment pushes against the vertebral artery. Further imaging with CTA (not shown) has not confirmed traumatic vascular injury of the right vertebral artery. 

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