unilateral facet dislocation
Unilateral facet dislocation is a relatively stable type of facet dislocation.
Pathology
Mechanism
Flexion/distraction associated with rotation. The inferior articular facet of vertebral above moves over the superior facet of the vertebral below and becomes locked. It usually affects C4-C5 or C5-C6 levels.
Radiographic features
Plain radiograph
- anterolisthesis of less than 25 - 50%
- as the other normally aligned facet prevents displacement greater than this
- if there is a greater amount of displacement, then bilateral facet joint dislocation should be considered
- bow-tie sign: rotated facets on lateral view
- rotation and misalignment of spinous processes on AP view which point to the involved side
- widening of the interspinous space at affected level
CT
- naked facet or inverted hamburger sign may be present
- also helpful to detect other fractures and their extent
MRI
MRI is used to detect other soft tissue injuries like disc herniation and cord edema/contusion.
Treatment and prognosis
30% of these injuries are associated with neurological deficit.
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Assoziationen und Differentialdiagnosen zu unilateral facet dislocation:
