Daily Bolus of LR: Cervical spine facet dislocations

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February 16, 2011 by dailybolusoflr

There are two types of facet dislocations: Unilateral facet dislocations and bilateral facet dislocations.

Unilateral facet dislocations:

· Mechanism is flexion and rotation

· One inferior facet of the vertebra on top is pushed anterior and over the superior facet of the vertebra below.

· The dislocation is always less than half of the diameter of the vertebral body

· This fracture is stable because the facets become locked.

· This is often missed on xray

· Imaging:

o Lateral- anterior displacement of a vertebral body less than 50% the diameter

o AP- line formed by the spinous processes is disrupted

Bilateral facet dislocations:
Mechanism is flexion

· The upper vertebra is pushed superior and anterior so that both inferior facets are moved forward in relation to the lower vertebra.

· The dislocation is a displacement of more than half of the diameter of the vertebral body

· This fracture is unstable as it disrupts the annulus fibrosis, the anterior longitudinal ligament and the posterior ligamentous complex. It is associated with a high percentage of spinal cord injuries.

· Imaging:

o Lateral: anterior displacement of a vertebral body more than 50% the diameter

Linda Regan, MD FACEP
Program Director, Emergency Medicine Residency
Johns Hopkins Medical Institutions

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