MAGNETIC-RESONANCE-IMAGING OF THORACOLUMB AR FRACTURES STABILIZED BY AN INTERNAL FIXATOR

To analyse the possible injuries of vertebral segments, especially the disc, after unstable thoracolumbar fractures stabilised with AO inter nal fixator,we performed magnetic resonance imaging (MRI) of the traum atised region after implant removal. There were two aspects of disc de generation (DD): (1) biochemical changes and (2) structural damage. MR I detects biochemical processes as one aspect of DD that is often smal l even in the presence of greater structural damage of the nucleus pul posus caused by fracture. None of the patients presented with structur al failure of the anulus fibrosus,which is the essential structural co mponent of the vertebral segments with regard to stability. We observe d biochemical changes more often in the lower of the two fracture-adja cent discs and alterations of discal shape more often in the upper of the two, whereas loss of height concerned both discs to approximately the same degree. The supporters of upper-disc resection in thoracolumb ar fractures justify their procedure among other things with the struc tural disc damage, such as alteration of shape and loss of height (alt ogether more frequent in the upper disc). Our observations that a disc with a structurally altered nucleus pulposus can be biochemically int act and can show an intact anulus fibrosus are arguments in favour of disc preservation. With regard to the upper disc, the widespread opini on that complete and regular disc damage requires a resection has to b e revised. The question of whether the lower disc should be resected m ore often because of its greater biochemical changes cannot be answere d by the present study alone. Besides the excellent static information in all anatomical structures of the vertebral column available by MRI , a repeat examination in a prone position yields dynamic information on the spinal cord in the case of suspected dorsal adhesions.