Fig. 14

Bilateral versus unilateral facet joint dislocation. a Mid-sagittal CT image shows anterior translation of C5 over C6 by more than 50 % anteroposterior width of the C6, highly suggestive of bilateral facet joint dislocation, which was confirmed on parasagittal images (not shown). Large triangular bony fragment is noted at the posteroinferior corner of C5 (arrow) with diffuse loss of C5–C6 intervertebral disc space. b Mid sagittal CT image shows anterior translation of C4 over C5 by less than 50 % anteroposterior width of C5 (approximately 25 %), highly suggestive of unilateral facet joint dislocation, which was confirmed on parasagittal images (not shown). Small triangular bony fragment is noted at the anteroinferior corner of C4 (arrow) with loss of C4–C5 disc space. Disruption of spinolaminar line (black curved lines) at the level of anterolisthesis with anterior displacement of the same vertebra and lamina (C5 in a and C4 in b) is highly suggestive of hyperflexion injury. Presence of small avulsion fragments at the discovertebral junction with loss of intervertebral disc height is associated with disc injury, which needs further evaluation with MRI