Biomechanical properties of thoracic spine with various locations of metastatic defects：three-dimensional finite element analysis / 中国组织工程研究

ABSTRACT

BACKGROUND:The spinal column is the most common site of cancer metastases. Most of the previous biomechanical experiments utilized models with defects only in the vertebral body or posterior elements, but the biomechanical changes of the thoracic vertebrae and posterior part with various locations of metastasis deserve further research. OBJECTIVE:To set up the three-dimensional (3D) finite element model to investigate biomechanical effects by simulating combined destruction of vertebral body and other posterior components. METHODS:Based on CT data, we constructed the 3D geometric models of the thoracic vertebrae (T9-11), including intervertebral discs, ligaments and ribs using the Mimics software. The 3D models of T9 vertebra and different parts of the posterior thoracic vertebrae related with the metastasis could be simulated, including the control group with the intact vertebrae, the group of the T10 vertebrae with the right defective hemi-vertebrae, the group of the defective hemi-vertebrae with the defective ipsilateral pedicle, the group of the defective hemi-vertebrae with the defective ipsilateral costovertebral joint, the group of the defective hemi-vertebrae with the defective ipsilateral pedicle and costovertebral joint, the group of the defective hemi-vertebrae with the defective ipsilateral pedicle, costovertebral joint and transverse process. The corresponding 3D finite element models were established using the Abaqus software. The displacement and Von Mises stress distribution of the models were analyzed when the anterior compressive flexure load was applied. RESULTS AND CONCLUSION:When the anterior compressive flexure load was applied, the entire stiffness was proportionaly decreased when the more posterior parts destroyed, especialy destruction of vertebral body and pedicle significantly decreased. The destruction of posterior structures such as the thoracic rib joints and transverse processes was not great. However, the maximal Von Mises stress increased significantly when the vertebral body and pedicle were destructed, but additional costovertebral joint destruction slightly decreased the maximal Von Mises stress because of the stress was re-distributed.