---

- Criteria for Unstable Frx:
    - Neurologic deficit;
    - Posterior Element Injuries;
    - Loss of more than 50% of anterior vertebral body height;
    - Greater than 25 to 35 deg of kyphosis;
    - Thoracolumbar burst frx:
           - angulation of thoracolumbar junction > 20 deg
           - canal comprimise > 30 percent

- Treatment:
    - Anterior Approach
    - Distraction Systems:
    - Multisegmented Hook Instrumentation
    - Posterolateral Decompression:

- Discussion:
    - in stable bust frxs, posterior column is uninjured & remains functional as tension band wheras unstable burst frx have comminution 
           or ligamentous damage to posterior column;
    - axial force will builds up sufficient pressure in disc to centripetally frx superior portion of vertebral body in all directions;
    - fragments usually remain attached to annulus & are contained w/ in intact anterior and posterior longitudinal ligaments;
    - unstable burst frx are prone to further collapse & retropulsion upon normal axial loading;
    - w/ severe compression frx (over 70% of the vertebral body), there will also be concomitant disruption of interspinous ligament;
           - frx will often settle into kyphosis with time