Finite Element Analysis Of The Total En Bloc Spondylectomy Of Cervicothoracic Spine

Total spondylectomy(TS)is considered to be the most effective treatment for malignant spinal tumor.It is increasingly favored by doctors because of its completely resection and the low recurrence rate of the tumor.The stability of the spine after the reconstruction has become the most important part because of the surgery needs to remove a whole section or several sections of the spine.Since there are fewer theoretical studies of this surgery than the experimental studies,the finite element analysis of the total spondylectomy for cervicothoracic spine has been report by this article.The three-dimensional finite element model of C5-T2 segment of cervicothoracic spine has been established based on the CT images with CAD and CAE technology.The intact model includes cortical bone,cancellous bone,rear bone,the annulus matrix,collagen fibers,nucleus pulposus,endplate,five kinds of ligaments and small joints.Five surgery models,the C7 sections of which were removed,were established based on the intact model with different kinds of internal fixation instruments implanted: 1.Reconstruction by titanium mesh and fixed by anterior plate and double-segmental pedicle screw(TM+AP+DPS);2.Reconstruction by titanium mesh and fixed by anterior plate and single-segmental pedicle screw(TM+AP+SPS);3.Reconstruction by titanium mesh and fixed by double-segmental pedicle screw(TM+DPS);4.Reconstruction by autologous bone and fixed by anterior plate and double-segmental pedicle screw Lossless model includes cortical bone(B+AP+DPS);5.Reconstruction by autologous bone and fixed by double-segmental pedicle screw(B+DPS).Loads in six different directions were applied to the intact model and the surgery models to simulate the activities of flexion,lateral bending and torsion of human body.The mechanical properties of the autogenous bones and the internal fixation instruments were analyzed by observing the stress distribution on them.The pros and cons of the surgery programs were evaluated by comparison of the mechanical properties of the models.The results showed that there’s no significant difference of the stiffness of the five surgery models and the effects of the fixation are close.Stress concentration occurred on the titanium mesh of the TM+AP+SPS model.The stress distribution and the effects of the fixation of TM+AP+DPS model and TM+DPS model are similar.In the same condition,the autogenous bone endure less stress than the titanium mesh and the valueand the distribution of stress on other internal fixation are close.So when it’s reconstructed by titanium mesh and fixed by double-segmental pedicle screw,it may be possibile that the anterior plate is not used during the surgery.When it’s reconstructed by the autogenous bone and fixed by double-segmental pedicle screw,it is essential that the anterior plate is used during the surgery.