FUNCTIONAL RADIOGRAPHS OF ACUTE THORACOLUMBAR BURST FRACTURES - A BIOMECHANICAL STUDY

The geometric changes of acute thoracolumbar burst fractures under ext ension and traction loadings were analyzed using functional radiograph s. The injuries were produced in an in vitro high-speed impact model. The changes in nine geometric parameters (three angular and six linear ) were analyzed from neutral posture to extension and traction positio ns. In the extended position, all parameters, except the posterior ver tebral height and vertebral diameter, were significantly different fro m the neutral posture values. Also in extension, the posterior vertebr al height, vertebral diameter, and posterior unit height were signific antly different from their intact values. In the traction position, al l nine geometric parameters changed significantly from the neutral pos ture, whereas only the vertebral diameter remained significantly diffe rent from its intact value. These findings demonstrated the treatment advantages of applying traction force to acute burst fractures in cont rast to extension moments. Further, changes in the angular parameters due to motion from neutral to extension posture demonstrated that the acute flexibility of the three-vertebrae segment was contributed almos t equally by the upper disc (35%), lower disc (27%), and fractured ver tebra (38%).