【作者】 张美超；

【导师】 钟世镇；

【作者基本信息】 第一军医大学 ， 人体解剖学， 2002， 博士

【摘要】 从临床应用角度出发，本课题旨在研究有限元法在骨科生物力学中的应用。通过有限元及配套影像方法，建立了合理、逼真、能准确反映实际问题的骨科生物力学有限元模型，针对临床上存在的实际问题，在脊柱相关力学问题、人工关节置换和医疗器械的生物力学性能评价等方面进行了仿真实验，并与实验研究相对照，对临床现象进行解释，同时为它们在临床上的应用提供生物力学上的依据和指导。在研究过程中，逐步摸索能够较好仿真生物力学问题的建模方法与仿真经验，并积累能够反映生物力学效应的有限元准标准模型，为下一步更系统地为临床工作服务作准备。 主要内容如下： 一、接触问题在生物力学研究中非常普遍，本文利用有限元法对腰椎小关节之间的接触现象进行了分析。腰椎小关节维护腰椎的正常运动，是腰椎运动节段重要的一部分。本文建立了L4-5正常运动节段的有限元模型，将两小关节面处理为接触模型，分析了小关节面在腰椎前屈、后伸、侧弯、旋转及压缩运动状态下的受力情况，发现小关节在承载方面作用较大，特别是抗旋转运动过程中作用更明显。 二、人工关节置换是近年来生物力学领域研究的热点，本文在腰椎4、5节段有限元模型基础上对人工椎间盘置换进行了分析。人工腰椎间盘置换术对腰椎运动节段生物力学特性的改变方向和程度尚未明确，人工腰椎间盘在临床上的应用缺乏理论依据与指导。在L4-5运动节段有限元模型的基础上，分别构建了L4-5运动节段的正常模型、退变模型和人工椎间盘置换模型，对三组模型分别施加前屈、后伸、侧弯、旋转与压缩五种运动状态的约束与载荷，以椎体、小关节为观察对象，比较它们在人工椎间盘置换前后力学性能的变化，同时对人工椎间盘盖板及人工髓核的力学特性进行分析，证明了人工椎间盘置换在临床上的合理性与可靠性，并对其中存在的问题提出了改进意见。 三、寰椎骨折是脊柱颈椎段常见的损伤，目前对各类型寰椎骨折的损伤机制尚不明确。Levine及Edwards把寰椎骨折分为后弓骨折、侧块骨折和Jefferson骨折三种类型。本研究建立了寰椎的三维有限元分析模型，通过对寰椎模型施加不同的约束与加载，模拟制造寰椎骨折的三种类型，并进行了有限元仿真计算。通过分析计算结果中衰椎应力、应变的分布及传导过程，对各种衰椎骨折进行了力学上的阐释，为其提供了结构力学上的理论依据。 四、建立了枢椎的三维有限元模型，对枢椎齿状突骨折机理进行了理论上的研究，重点针对临床上齿突骨折的三种分类：1、齿突尖骨折；2、齿突腰部骨折；3、齿突基底部骨折，赋予齿状突在矢状面沿各种角度下受力条件，模拟衰椎前弓、襄椎横韧带以及CZ－3棘间韧带对枢椎造成的暴力破坏，确定了最可能引起齿状突暴力骨折的受力角度。另外，单独设定了Han驯an骨折的载荷条件，计算分析结果与预期接近。 五、医疗器械的生物力学特性是临床外科医生关心的问题，各类骨科内、外固定器械的结构稳定性、强度极限、抗疲劳性、共振现象和冲击特性等关系到其在临床中应用的合理性与安全可靠性。本文从临床角度出发，通过临床外科医生的协作，对如何利用有限元来解决这些问题进行了研究，提出了自己的见解。同时，通过对颈前路蝶型钢扳（MAPI）、胸腰椎前路K型钢扳、短节段腰椎滑脱复位固定器、人工股骨头等医疗器械进行具体分析，为它们的临床应用提供指导，同时对这些方法进行了实例验证。更多还原

【Abstract】 This paper aimed at the appliance of finite element method(FEM) on orthopaedic biomechanics to serve for clinic. Proper, vivid and effective models about biomechanical problems were build and studied in this paper, such as the mechanical problems correlative with the human spine, artificial joint replacement and the evaluation of orthopaedic instruments et al. Some of the results were compared with that obtained from experiments to explain the clinical phenomenon as well as to provide biomechanical proof and direction for clinical appliance. On this process, good methods on reconstruction and simulation were explored, and some good models that can reflect the biomechanical effect were accumulated for the next studies. Main studies are shown below:1. Contact is very common in the study of biomechanics. In this paper, the contact phenomenon exists on lumbar facet joints were analysed. The lumbar facet joints play a considerable part in resisting the intervertebral loads. A three-dimension FEM model of normal L4-5 was built, and the lumbar facet joints were treated as to contact with each other. Various motions of L4-5 were simulated by changing the loads: anteflexion, retroversion, right rotation, right bending and longitudinal compression. The strain and stress on both sides of the facet joints were calculated, analysed and compared with each other. As a conclusion, the lumber facet joints bear the largest loads in axial rotation among the five motions.2. Artificial joint replacement is the hotspot in biomechanics recently. In this paper, the artificial disc replacement on L4-5 was studied. The artificial disc replacement on lumbar is a new kind of operation, and the changes of mechanics aroused by it are not very clear, which restrict it’s application on clinics. On the-3-basis of FEM model L4-5, three kinds of models were built to simulate the normal disc, the degraded disc and the artificial disc. Under the same conditions as specified in item 3, the strain and stress in the L4-5 and the facet joints were calculated and compared with each other. Additionally, the artificial disc was analysed to confirm its rationality and safety as well as its deficiency.3. The fracture mechanism of the atlas(Cl) were studied in this paper. Levine and Edwards divided the fracture of Cl into three types: type I :the posterior arch fracture; typell:the lateral mass fracture and type III: the Jefferson fracture. A three-dimensional FEM model of atlas was constructed and analysed to simulate each kind of fracture. From the simulations, we can see the distributions and transmission of strain and stress in model under different loadings, and the results explained the fractures very well.4. Similarly, a axis FEM model was constructed to simulate the axis fracture, emphasized on the odontoid process. Three kind of odontoid process fracture were analysed on this model, which occurred respectively on the tip, the middle and the fundus. The results gave the best angle to fracture the odontoid process of the axis. Additionally, the Hangman atlas fracture was simulated and the calculation gave the expected results.5. The biomechanical features of medical treatment instruments are concerned by clinicians, which is composed of structure stability, intensity limitation, anti-fatigue, resonance-responding and impact characters et al. These features are all related to the rationality and safety of instruments. In this paper, FEM were applied and personal techniques were bring forward to solve these problems. Examples of the analysis by finite element method were also shown in it, which includes: the modified anterior plate instrumentation(MAPI), the anterior thoracolumbar K-plate system, the short reduction-fixation(HOIST device) for lumbar spondylolisthesis and the artificial femoral head.更多还原