Abstract:

BACKGROUND: It has recently been reported in the literature that segmental fixation with screws at the level of the fracture achieves improved stability over conventional four-screw fixation because it effectively reduces the incidence of screw loosening and internal fixation fracture, but the research about the biomechanics is inadequate.
OBJECTIVE: To construct a three-dimensional finite element model of thoracolumbar vertebral compression fractures and to investigate the biomechanical mechanism of the treatment about thoracolumbar vertebral compression fractures with pedicle screws in injured level.
METHODS: The ultrathin CT scan data obtained from one young male patient with the compression fractures of T12 were put into the Materialise Mimics to reconstruct a compression fracture model of T12. The fracture model was treated respectively with six and four pedicle screws. Vertical compression, flexion, extension, left and right bending loadings were performed.
RESULTS AND CONCLUSION: The largest stress was measured in the screw root. The stress under the vertical loading was the lowest, while those under the right bending and left flexion loadings were the highest. The stress of the superior screw was larger than that of the subordinate screw (P < 0.05). The stress in the four-screw group was larger than that in the six-screw group (P < 0.05). The maximal deflection of T11 under different loadings had no difference between the two groups. It is indicated that it can be optimized to reduce the failure of internal fixation with pedicle screws in injured level.