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Hyperextension Injuries: (19-38% of cervical injuries)


- See:
    - Central Cord Syndrome:
    - Extension Teardrop Fracture of C2
    - Hangman's frx
    - Jefferson Fracture
    - Lower Cervical Burst Fractures
    - Hyperextension fracture dislocation
    - Prevertebral Soft Tissues
- Discussion:
    - hyperextension injuries may include:
         - hyperextension sprain;
         - Hyperextension dislocation;
         - traumatic spondylolisthesis (Hangman's frx of C2);
         - avulsion injury of the Atlas or Axis;
         - isolated laminar fractures;
    - may occur from a blow to the face (& accompanied w/ fascial frx)
    - mechanism involves distractive anterior forces and compressive Posterior column forces;
    - pts w/ severe Spondylosis may suffer neurologic deficit w/ no radiographic fractures or subluxations;
    - cord is pinched between posteriorly projecting osteophytes & thickened, bulging ligamentum flavum;
    - C2 Laminar Frx:
           - isolated laminar frx of Axis have also been described & may be confused w/ traumatic spondylolisthesis;
           - laminar frx occurs posterior to the pars interarticularis, & unlike Hangman's frx, is considered a stable injury;
           - because of diffus sclerosis in pts w/ Spondylosis, laminar frx may be difficult to detect on plain films;
           - while they are stable, fragments may compromise canal & impinge on cervical cord resulting in deficits;
    - injuries resulting in anterolisthesis include:
           - unilateral facet subluxation (shows > 3-6 mm of anterior offset)
           - hyperflexion strain - results in less offset;
- Radiographs:
    - unilateral articular mass frx are seen on AP film as disruption of undulating lataeral margin;
    - lateral film:
    - oblique film:
    - prevertebral soft tissue swelling;
    - widening of intervertebral disc space;
    - fractures of the posterior elements;
- Treatment:
     - pts with cord or nerve root dysfunction due to hyper-extension injuries are managed non surgically with an orthosis, & their neurologic 
           status is carefully monitored


Hyperextension-dislocation of the cervical spine. Ligament injuries demonstrated by magnetic resonance imaging.