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Duke Orthopaedics
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Wheeless' Textbook of Orthopaedics

Facet Joint Injuries



- See:
     - Bilateral InterFacet Dislocation
     - Hyperflexion Injuries
     - Unilateral Facet Dislocation:

- Discussion:
    - frequently missed in acute cervical spine trauma; (oblique radiograph views are important here);
    - lateral mass frx is considered to be extension rotational injury;
    - flexion of superior vertebral body usually does not occur, because subluxing inferior articularprocess does not have to ride up intact 
           superior process;
    - inferior process fractures are typically at base of process and tend not to be associated
           with neurologic deficit, because neuroforamen is not narrowed;
    - w/ high-grade anterior subluxation (>/= 50%), there is little anterior shear resistance by the disk or ligaments;
    - associated injuries:
           - unilateral or bilateral facet joint subluxation or dislocation is seen;
                  - contralateral facet subluxation & anterolisthesis is common;
           - apical frxs of superior process are usually assoc w/ transient high-grade bilateral facet subluxation and cord injury;
           - w/ frx of articular process & subluxation or dislocation there is no longer bony resistance to forward
                  subluxation (superior articular process of lower vertebra is compromised);
           - frx fragment may be small enough that remaining part of superior process provides an adequate bony block;
           - laminar frx:
                  - may be missed on routine radiographs due to the obliquity of the lamina;
                  - facet frx which extend into the lamina will be more unstable and less amenable to closed treatment;
    - neurologic findings
           - basal frxs of superior process typically are assoc w/ root or cord deficit because vertebral
                  subluxation cannot be resisted by incompetent superior articular process;


- Radiographs of Facet Frx:
    - AP
           - disruption of undulating lataeral margin;
    - Lateral View:
           - facet injuries may be difficult to see on the lateral view due to overlap of both facets;
    - Pillar View
           - depicts the lateral mass en face;
           - frx typically extends vertically thru articular mass & separate fragment, or fragments, may be depressed or displaced laterally;
    - Oblique projections;
           - articular process frx can be overlooked, if intervertebral realignment has already occurred spontaneously;
           - look for discrete frx lines as well as facet disarticulation;
           - pillar frx is usually visible in inferior articulating facet of involved mass;
           - may not be visible is if vertical plane of frx line does not coincide with obliquity of projections;

- Non Operative Treatment:
    - small apical frx of superior process w/o subluxation on dynamic lateral radiographs may be treated with an orthosis;


- Operative Treatment:
    - displaced articular process frxs are treated w/ posterior wiring & grafting, because orthosis, including halo, may not maintain reduction 
           and prolonged traction may not be practical;
    - spinous process wiring:
           - alone may not provide derotating force needed to maintain realignment;
           
    - oblique facet wiring technique:
          - wire passes thru inferior articular process then around spinous process of subjacent vertebra;
          - it resists both forward & upward motion of inferior facet process


References 

Facet fracture-dislocation injuries of the cervical spine.

Unilateral facet dislocations and fracture-dislocations of the cervical spine.



Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Wednesday, December 21, 2011 3:04 pm