Ren Jie, Lyu Zhi
Department of Orthopaedics, the Second Hospital of Shanxi Medical University, Taiyuan 030001, Shanxi, China.
Zhongguo Gu Shang. 2021 Aug 25;34(8):764-9. doi: 10.12200/j.issn.1003-0034.2021.08.014.
The finite element analysis method was used to compare the biomechanical performance of the individualized interbody fusion cage, the clinically common double bullet type fusion cage and the healthy lumbar spine model under different working conditions.
According to the CT scan data of the lumbar spine of a real healthy human body, a finite element model of the lumbar spine of a healthy human body was designed using finite element software as a normal control group. On this basis, the individualized lumbar fusion cage model and the clinical standard bullet type fusion cage lumbar spine model were further established. These three finite element models were applied with different loads such as vertical compression, forward flexion, extension, and lateral bending to observethe changes in the stress distribution and stress magnitude of each component of the lumbar spine.
The maximum stress values of the vertebral body and the fusion cage under the extension condition in the clinical standard bullet type fusion cage lumbar spine model were 45.81 MPa and 97.07 MPa, respectively. The stress of the vertebral body and the fusion cage in the individualized lumbar fusion cage model was closer to the stress of the vertebral body and the intervertebral disc in the healthy lumbar spine model. From the perspective of displacement, the displacement of each component of the lumbar spine models of the two fusion cages was smaller than that of the healthy lumbar spine model, indicated that the internal fixation of the fusion cage limited the range of motion of the vertebral body. On the other hand, it also confirmed the validity of the finite element model established in the study. The displacement of the fusion cage and the vertebral body in the individualized model under different working conditions was generally smaller thanthat of the standard model fusion cage and the vertebral body.
The fusion cage can replace the diseased intervertebral disc to a certain extent, so as to reduce the patient's pain and restore the lumbar function. The personalized design of the fusion cage can better meet the needs of individual patients, which has the great significance to the recovery of the patient's lumbar spine function, the service life of the fusion cage and the protection of the contact vertebral body, and provides certain guidance for actual clinical treatment.
采用有限元分析方法，比较个体化椎间融合器、临床常用的双子弹型融合器与健康腰椎模型在不同工况下的生物力学性能。
根据真实健康人体腰椎的CT扫描数据，使用有限元软件设计健康人体腰椎的有限元模型作为正常对照组。在此基础上，进一步建立个体化腰椎融合器模型和临床标准子弹型融合器腰椎模型。对这三种有限元模型施加垂直压缩、前屈、后伸和侧弯等不同载荷，观察腰椎各部件应力分布和应力大小的变化。
临床标准子弹型融合器腰椎模型在后伸工况下椎体和融合器的最大应力值分别为45.81MPa和97.07MPa。个体化腰椎融合器模型中椎体和融合器的应力更接近健康腰椎模型中椎体和椎间盘的应力。从位移角度看，两种融合器腰椎模型各部件的位移均小于健康腰椎模型，表明融合器内固定限制了椎体的活动范围。另一方面，也证实了本研究建立的有限元模型的有效性。个体化模型在不同工况下融合器和椎体的位移总体小于标准模型融合器和椎体的位移。
融合器能在一定程度上替代病变椎间盘，从而减轻患者疼痛并恢复腰椎功能。融合器的个性化设计能更好地满足个体患者需求，对患者腰椎功能恢复、融合器使用寿命及接触椎体保护具有重要意义，为实际临床治疗提供一定指导。
