Finite element analysis of human lumbar vertebrae in internal fixation system model with different bone density trajectories.

Purpose: To evaluate the biomechanics effect of modified cortical bone screw technique (MCBT) with other traditional internal fixation systems on lumbar osteoporotic wet specimen.

Methods: Four different finite element models were established using CT data: (1) lumbar osteoporosis model without internal fixation system; (2) traditional pedicle screw technology (TT) model; (3) traditional cortical bone screw technology (CBT) model; (4) MCBT model. The changes of global displacement, intervertebral disc displacement of all models and internal fixation system Von Mises stress among the three models were compared under the same physiological load.

Results: Compared with the other three models, the total displacement of the modified CBT screw model was the smallest, with the maximum displacement of 0.216 mm; The intervertebral disc displacement of the modified CBT screw model was the smallest, with the maximum displacement of 0.149 mm; the internal fixation system Von Mises stress of the modified CBT screw technique model was the largest compared with the other three models, The maximum Von Mises stress is 232.73 MPa.

Conclusion: Compared to traditional pedicle screw and traditional CBT, MCBT has better mechanical stability, and it is of certain clinical application value.