3D打印聚醚醚酮（PEEK）基复合材料人工椎体力学性能的有限元研究

Finite element analysis of the mechanical properties of 3D-printed artificial vertebral body of PEEK matrix composites

中文关键词:  人工椎体  聚醚醚酮  有限元  应力遮挡率

英文关键词:Artificial vertebral body  Polyetheretherketone  Finite elements  Stress occlusion rate

中文摘要:

  【摘要】 目的：通过有限元法分析3D打印的聚醚醚酮（polyetheretherketone，PEEK）基复合材料的个性化人工椎体置入后的力学性能及对相邻组织的影响。方法：提取一名男性健康志愿者的腰椎CT扫描数据进行三维重建，构建腰椎（L1~L5）有限元模型，仿真各体态下不同腰椎节段的活动度，并通过与以往研究文献研究数据比较进行有效性验证。模拟全椎体切除术（total en bloc spondylectomy，TES）切除L3椎体及相邻椎间盘，基于人工椎体的设计原则，设计了个性化人工椎体，并采用后路固定的方式使用钛合金钉棒与相邻腰椎固定。人工椎体内部设计为30%、50%、70%致密度的蜂窝结构，选择PEEK/羟基磷灰石（hydroxylaptite，HA）复合材料作为个性化腰椎人工椎体外部壳体，以PEEK/碳纤维（carbon fiber，CF）材料作为内部填充物。通过Vicon Nexus系统得到直立、前屈、后伸、侧弯、旋转状态下椎体所受力和力矩，作为有限元分析的边界条件，选择合适的植骨孔大小和壳体厚度，对人工椎体内部使用不同致密度的六边形蜂窝进行填充，通过改变皮质骨和松质骨的弹性模量建立青壮年组和中老年组模型，对模型进行有限元仿真，通过统计分析人工椎体、固定系统和相邻上下终板在不同运动状态下的最大应力值以及人工椎体的应力遮挡率的大小，分析人工椎体的性能优劣。结果：人工椎体最大应力值（42.25MPa）低于PEEK/HA的屈服强度（65MPa），内部蜂窝最大应力值（26.38MPa）低于PEEK/CF的屈服强度（90MPa），钉棒固定系统的最大应力值（271.75MPa）低于钛合金的屈服强度（900MPa），相邻终板最大应力值（7.87MPa）低于软骨终板的屈服强度（50MPa），中老年组30%蜂窝致密度的人工椎体应力遮挡率最低。结论：3D打印的PEEK基复合材料人工椎体可以较好地完成TES后腰椎结构的重建，具有较好的生物力学稳定性。

英文摘要:

  【Abstract】 Objectives: To analyze the mechanical properties of the personalized artificial vertebral body of 3D-printed polyetheretherketone(PEEK) matrix composites after implantation and its effect on adjacent tissues using finite element analysis. Methods: The CT scan data of a healthy male volunteer was extracted for 3D reconstruction, the finite element model of the lumbar spine(L1-L5) was constructed, and the ranges of motion of different lumbar vertebrae segments in various motion states were simulated, after that, the effectiveness of the finite element model was verified by comparing with the research data in previous studies. The total en bloc spondylectomy(TES) was simulated to remove the L3 vertebral body and adjacent intervertebral discs, and a personalized artificial vertebral body was designed based on the design principles of artificial vertebral body and was fixed to the adjacent lumbar segments using a posterior approach with a titanium alloy rod-screw system. The interior of the artificial vertebral body was designed as honeycomb structures with densities of 30%, 50%, and 70%. PEEK/hydroxylaptite(HA) composite materials were selected as the external shell of the personalized lumbar artificial vertebral body, and PEEK/carbon fiber(CF) materials were used as the internal filler. The forces and moments of each vertebral body in the upright, forward bending, backward extension, lateral bending and rotation states were obtained through the Vicon Nexus system, and as the boundary conditions of finite element analysis, the appropriate size of the bone graft hole and the thickness of the shell were selected, and then the inside of the artificial vertebral body was filled with hexagonal honeycombs of different densities. The models of young and middle-aged and elderly groups were established by changing the elastic modulus of cortical bone and cancellous bone, and the finite element simulation was carried out on the models. The maximum stress values of the artificial vertebral body, fixation system and adjacent upper and lower endplates under different motion states, and the stress occlusion rate of the artificial vertebral body were analyzed to evaluate the performance of the artificial vertebral body. Results: The maximum stress value of artificial vertebral body(42.25MPa) was lower than the yield strength of PEEK/HA(65MPa), and the maximum stress value of internal honeycomb(26.38MPa) was lower than the yield strength of PEEK/CF(90MPa); The maximum stress value of rod-screw system (271.75MPa) was lower than the yield strength of titanium alloy(900MPa), and the maximum stress value of the endplate on adjacent endplate(7.87MPa) was lower than the yield strength of cartilage endplate(50MPa). The stress occlusion rate of artificial vertebral body with 30% honeycomb density in the middle-aged and elderly group was the lowest. Conclusions: The 3D-printed personalized artificial vertebral body of PEEK matrix composite can complete the structure reconstruction of lumbar spine well after TES with good biomechanical stability.