naked facet sign


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A fanciful term referring to the CT appearance of a bare vertebral articular facet in facet joint dislocation
Background The normal vertebral facet (apophyseal) joint space looks like a hamburger on axial CT: the superior articular process of the vertebra below forms a semicircular 'bun' atop the 'meat patty’; the inferior articular process of the vertebra above forms the bun beneath the patty. In facet joint dislocation, the articular facets are uncovered: the ‘hamburger bun’—the superior articular facet—lies posteriorly. The sign may be either unilateral if the facet dislocation is unilateral or bilateral if the dislocation is bilateral
Aetiology Flexion-distraction injury; a positive hamburger sign indicates severe ligamentous disruption and spinal instability

naked facet sign

The radiographic appearance of spinal facet joints that have been disrupted by flexion injuries to the thoracic or lumbar spine. CT scanning of the joints shows that the inferior facets of the upper vertebrae are not directly aligned above the superior facets of the lower vertebrae.
Synonym: hamburger sign
See also: sign