关键词: 胸腰段, 爆裂骨折, 植骨, 有限元

Abstract:

Objective　To construct a finite element model(FEM) of first lumbar vertebral burst fracture, and compare the stress distributions between transpedicular grafting and transcanal grafting.    Method    The FEM of normal thoracolumbar segment T12~L2 with first lumbar vertebral burst fracture was established through thin layer CT scan, three-dimensional reconstruction by using Mimics and ANSYS software, respectively. The model was fixed by the posterior pedicle screws. On the basis of the models, we subsequently generated another 2 models simulating 2 types of surgical techniques, transpedicular grafting (TPG) and transcanal  grafting(TCG). The stress distribution of model was observed in the respective 4 models when spine was exposed to a stress of 350N/8Nm in the position of flexion, extension，lateral bending and rotation.    Results　Through the static analysis of Ansys software, it was concluded 4 model under various conditions of equivalent stress nephogram, and display the equivalent stress peak, flexion: 6.89, 54.10, 8.03, 5.92 MPa; extension: 56.70, 109.00, 12.50, 8.61 MPa; lateral bending: 6.83, 47.50, 11.30, 3.60 MPa; rotation: 23.80, 112.00, 13.10, 7.65 MPa. Not concentrated stress at the time of bone graft screw of the tail and connecting rods, stress significantly decreased after bone graft, assuming a scattered distribution to the central screw.    Conclusion    Both of the 2 types of grafting procedure/technique can reconstruct the strength of injured vertebrae and enhance the instant stability. Nevertheless, the technique of transcanal grafting may offer a better mechanical performance through decreasing the stress on the internal fixation in a more adequate and efficient way. Therefore this study concludes that it is a better surgical technique worth of being popularized in clinic.

Key words: Thoracolumbar, Burst fracture, Bone grafting, Finite element