Unilateral Locked Facets:  Stable

This results from simultaneous flexion and rotation. One of the articular masses is displaced anterior to the subjacent mass.  There is subluxation and locking at the facet joint.  

You can see forward displacement of the dislocated vertebral body a distance less than 50% of the AP diameter of the vertebral body.  

There should be no significant listhesis and no abnormal gapping of either the vertebral body or spinous processes.  

This represents a stable minor ligamentous injury.

 
C3 Jumped Facet     

    
Magnified view of C3 Jumped Facet

Unilateral Locked Facet of C6

    
Magnified Views of C6 Unilateral Locked Facet.

Findings:  There is prevertebral soft tissue swelling, abrupt change in rotation at the involved level.  Grade I Anterolisthesis of C6 on C7.  The remaining facets are superimposed.