L5新型自稳定人工椎体生物力学性能的有限元分析

Analysis of biomechanical properties of a new type of self－stabilizing artificial vertebral body L5 spine by finite element

中文关键词:  人工椎体  钛笼  腰骶段  有限元分析  生物力学

英文关键词:Artificial vertebral body  Titanium cage  Finite element analysis  Spine  Biomechanics

中文摘要:

  【摘要】 目的：采用有限元分析评估L5椎体次全切术后置入新型自稳定人工椎体的力学性能以及对周围组织的影响，为腰骶段脊柱结核等疾病的治疗提供新的选择。方法：提取1名健康志愿者腰骶段CT薄层扫描数据进行三维重建，构建腰骶段（L3-S1）脊柱生理组有限元模型并进行有效性验证。将L5椎体及邻近椎间盘切除后，分别置入新型自稳定人工椎体和钛笼联合侧前方钉棒固定，构建新型假体组和钛笼组有限元模型。对所有模型的S1椎体下表面进行全部自由度约束，在L3椎体上表面给予400N的轴向载荷模拟生理压缩，然后再在L3椎体上表面施加8Nm的弯矩载荷，模拟腰椎前屈、背伸、左右侧弯及左右扭转六种运动，统计分析在不同运动方向上三组模型L4~S1的活动度及L4下终板和S1上终板的最大Von mise应力。结果：新型假体组和钛笼组L4~S1在前屈、背伸、侧弯、扭转方向上的活动度分别为0.38°~0.56°与0.53°~1.41°，较生理组（4.48°~10.12°）同部位活动动度明显减小。新型假体组和钛笼组L4下终板与S1上终板在前屈、背伸、左右侧弯、左右扭转方向上的最大Von Mises应力较生理组均明显增大，新型假体组在上述方向上终板的最大Von Mises应力较钛笼组明显减小。结论：自稳定人工椎体可以较好地重建手术部位的即刻稳定性，有效降低手术部位邻近终板的局部应力，理论上可以降低术后假体的下沉率，但其长期稳定性、抗疲劳性等力学性能尚需进一步研究。

英文摘要:

  【Abstract】 Objectives: To evaluate the mechanical properties of the new self stabilizing artificial vertebral body after L5 subtotal corpectomy and its influence on the surrounding tissues used finite element analysis, so as to provide a new choice for the treatment of lumbosacral spinal tuberculosis and other diseases. Methods: The CT thin-slice scan data of lumbosacral segment of a healthy volunteer were extracted and 3D reconstruction was performed to construct the finite element analysis model of lumbosacral segment(L3-S1) intact group and verify its validity. After the L5 vertebral body and adjacent discectomy, the new artificial vertebral body and the titanium cage combined with the anterior titanium rod were placed respectively, and then the finite element analysis models of the new prosthesis group and the titanium cage group were constructed. For the inferior surface of S1 vertebral bodies of all models of all degrees of freedom, 400N axial loads of simulated physiological compression were applied on the superior surface of L3 vertebral body, and then 8Nm bending loads were applied were also applied on the superior surface of L3 vertebral body surface to simulate the six movements of flexion, extension, left/right lateral bending, and left/right rotation of lumbar spine. The ROM of L4-S1 and the maximum von Mises stress of adjacent end plate were analyzed statistically. Results: The ranges of motion in the flexion, extension, lateral flexion and rotation of the new prosthesis group and the titanium cage group were 0.38°-0.56° and 0.53°-1.41°, respectively, which were significantly lower than those in the intact group(4.48°－10.12°). The maximum von Mises stress of the endplate at the operation site(lower endplate of L4 and upper endplate of S1) of the new prosthesis group and the titanium cage group were significantly increased in the flexion, extension, lateral bending and rotation directions, but the maximum von Mises stress of the new prosthesis group was significantly decreased compared with the titanium cage group in the above directions. Conclusions: The self-stabilizing artificial vertebral body can not only reconstruct the immediate stability of the surgical site, but also effectively reduce the local stress on the endplate of the surgical site, and to some extent reduce the postoperative subsidence rate of the prosthesis. However, the mechanical properties of the new prosthesis, such as long-term stability and fatigue resistance, need to be further studied.