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Flexion-Distraction Injuries (Seat Belt Types)



- See:
       - Chance Frx:
       - Fracture Dislocation:

- Definition:
    - flexion distraction injuries may occur thru bone or soft tissue, and they may involve one or several levels;
    - flexion distraction injuries occur secondary to distractive disruption of posterior & middle columns w/ compression failure of 
           anterior column;
    - Chance Frx:
           - anterior, middle, and posterior columns all fail in tension;
    - mechanism of injury:
    - associated injuries:
           - most common injuries in lap belt restrained passengers are bowel trauma and lumbar spine frxs;
           - crushing of the bowel between the lap seat belt and spinal column results in devascularization or acute bowel rupture;
           - references:
                  - The epidemiology of seatbelt-associated injuries.

- Radiographs:
    - increased interspinous process distance on AP view;
    - lateral view:
          - increased posterior height of vertebral body is seen on lateral film;
          - split spinous process is seen, esp on lateral tomograms;
    - often these are misdiagnosed as a compression frx;
          - the occurance of a traumatic compression fracture in a young patient (following MVA) should raise the possibility of a Chance fracture;
          - either good quality AP view is necessary to rule out posterior element injury, or a CT scan is required (if the AP view remains 
                 equivocal);
    - CT is not of help in many distraction type of injuries because plane of injury is in the plane of the CT scan;
           - CT cuts tend to be a few milimeters above or below injury;

- Non Operative Treatment:
    - if injury goes through vertebral body rather than disc space, interdigitation of cancellous bone gives a great deal of immediate stability & 
           rapidly heals;
    - when these injuries occur entirely thru bone, treatment is in a hyperextension cast;
    - complications:
          - if there is crushing of bone frx can settle into kyphosis because of associated disruption of posterior interspinous ligaments;

- Operative Treatment:
    - when posterior and middle columns fail by ligamentous disruption, posterior spinal fusion with a compression system is advocated;
          - however, it is important to determine whether the middle column is capable of load bearing;
                 - if this is not the case, use of compression system could lead to retropulsion of bone or disk fragments into the canal



Anterolateral compression fracture of the thoracolumbar spine. A seat belt injury.

Seat-belt injuries of the spine in young children.

Pediatric Chance fractures: association with intra-abdominal injuries and seatbelt use.

Patterns and mechanisms of lumbar injuries associated with lapseat belts.

The diagnosis and treatment of pediatric lumbar spine injuries caused by rear seat lap belts.