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2022, Vol. 26 ›› Issue (6): 864-869Finite element analysis of different angles of nail placement in sagittal plane of spinal fractureWei Bing1, Chang Shan2
Abstract: BACKGROUND: For patients with spinal fractures, when the surgeon adopts the method of posterior implantation and nail placement, different angles will be adopted according to his own habits, but which angle is better for the postoperative effect is not yet clear. OBJECTIVE: To establish a finite element model of thoracolumbar vertebral body fracture to explore the influence of pedicle screws placed at different angles in the sagittal plane on spinal stability. METHODS: Three young and middle-aged patients with fresh compression fractures of the lumbar 1 vertebral body were selected. The fracture model was constructed by finite element software (lumbar 1 vertebral body fracture, T12-L2 model), and the HyperMesh assembly screw was used to establish the model of the L1 fracture at three different angles (sagittal plane is parallel to the upper endplate; obliquely upward endplate 7°; obliquely downward endplate 7°) in the sagittal plane. Various loads were applied to the model, and biomechanical analysis of its force was conducted. RESULTS AND CONCLUSION: In the vertical state, the maximum displacement of the vertebral body after different nail placement methods all appeared on the surface of the thoracic 12 vertebral body. In the torsion state, the maximum displacement of the vertebral body all moved back to the upper vertebral body in the posterior column part and the upper part of the connecting rod. In the forward flexion state, the maximum displacement of the vertebral body occurred at the front edge or the posterior column part of the thoracic 12 vertebral body. In the extension state, the maximum displacement of the vertebral body was mainly concentrated in the posterior column of the thoracic 12 vertebral body. In the scoliosis state, the larger displacement of the vertebral body was mainly concentrated on the scoliosis side of the thoracic 12 vertebral body. In the same state, the body displacement of all vertebrae with the oblique upward screw is the smallest, indicating that the vertebral body will be more stable if the screw is placed at an angle of 7°. Key words:fracture, spinal fracture, posterior nail placement, finite element analysis, pedicle screw, stability, sagittal angle |