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 articular
            process 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;

---

Facet fracture-dislocation injuries of the cervical spine.

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

---