Biomechanic Study And Clinical Analysis Of The Thoracolumbar Burst Fracture

The first part of this article is to study the anatomic factors of the reduction of fragment in the spinal canal for thoracolumbar burst fracture and the related biomechanic relationship. Using burst fracture model of L1 made by fresh thoracolumbar spine ( T11～L3 ), the change of the narrowest place in the spinal canal under axial distraction was drew. At the same speed for group one (Group Ⅰ)with the posterior longitudinal ligament (PLL) being intact and the fibrous annulus being cut off, group two (Group Ⅱ)with the fibrous annulus being intact and the PLL being cut off, group three (Group Ⅲ)with both being intact, the curve of the relationship between the reduction percentage of fragment and the axial distraction was drawn. Then it is found that the curves of the relationship between the reduction percentages of fragment and the axial distraction were "s"shaped. Curves ascended slowly and the axial distractions rised progressively on the sequence of Group Ⅰ, Ⅱ, Ⅲin pre-reduction period. Curves ascended acutely in reduction period. The axial distraction and the reduction percentages rised on the sequence of Group Ⅰ, Ⅲand Ⅱ. There was still a significant reduction curve during the post-reduction period. The conclusions are that the axial distraction takes an important role on the reduction of fragment in the spinal canal for the thoracolumbar burst fracture, and intact PLL and fibrous annulus take a key role in the course of the reduction of fragment. The second part of this article is to compare the effects of two surgical methods for posterior decompression on the treatment of thoracolumbar burst fractures. Through the retrospective analysis from March 1998 to January...