A Finite Element Simulation of the Dynamic Burst Fracture Process

Following a burst fracture, decompressive surgery is often recommended on the basis of imaging alone. There is, however, doubt as to whether the observed fragment position represents the true extent of canal occlusion that occurs during the fracture process. A dynamic finite element model, validated against high-speed video images of an experimental burst fracture, was used to simulate the projection of the fragment into the spinal canal. At high levels of canal occlusion, the presence of the spinal cord was found to be significant, with both the cord and the posterior longitudinal ligament acting to reflect the fragment back towards the vertebral body. The greatest cord pressure occurred at maximum dynamic occlusion and this is likely to cause the greatest neurological damage. The final fragment position caused less canal occlusion than occurred dynamically and is therefore not a good indication of the damage that occurs at the moment of injury.