Finite element analysis of a "U" shaped lumbar dynamic fixation rod

Self-made spring Ni-Ti memory alloy rod was combined with Ti alloy pedicle screw to compose elastic internal fixation system. Spiral CT was used to scan the elastic fixator. Finite element model and solid model were constructed by ANSYS8.0 software after profile extraction and threshold dissection. The stress and displacement of every nodule and element in the course of deformation of the rod were tested and compared with traditional Ti alloy rod. In axial compression, extension and flexion load, the force of the dynamic rod was concentrated on the "U" shaped elastic zone. The results demonstrate the "U" shaped rod has a good biomechanical pkoperty. This dynamic fixation system may be a choice to replace the rigid fixation system for the lumbar degenerative disease.