【作者】 王甲甲；

【导师】 任露泉； 钱志辉；

【作者基本信息】 吉林大学 ， 农业机械化工程， 2014， 博士

【摘要】 当代社会，人们生活方式的改变导致颈椎病呈现高发病率、职业化、年轻化的趋势；车辆交通事故频发也使得颈部损伤成为一种常见的损伤形式。颈椎生物力学研究有助于提高对颈椎伤病发病机制的认识和理解，为颈椎伤病的预防和治疗提供理论基础。其中，有限元方法以其可重复性、便于参数化研究、成本低等优点成为比较理想的研究手段，已在颈椎发病及损伤机制、临床术式、颈椎人工假体设计等方面得到广泛应用。同时，颈椎椎间融合器常用于前路融合手术中，具有实现术后即刻稳定、撑开和维持椎间隙高度、促进融合等优点，因而在颈椎前路手术中得到了快速发展。但与之伴随的下沉、移位、不融合等相关并发症也越来越引起人们的重视。本文基于人体头颈部运动生物力学试验测试、头颈部医学图像及逆向工程技术对人体颈椎运动进行了有限元建模研究，并利用仿生学理念设计了具有仿生表面形态的颈椎椎间融合器；结合生物耦合及耦合仿生理论对耦合仿生颈椎椎间融合器进行了研究。基于运动生物力学试验测试方法，设计了7个Marker反光标记点对头部及颈椎棘突点进行标记。利用三维运动分析系统，对受试对象的头颈部在前屈、左/右侧弯及左/右旋转5种正常生理运动状态下的运动学特性进行试验研究。结果表明，任意测试运动状态下，上颈椎（C2）的运动范围均明显大于下颈椎（C6、C7）的运动范围；与头部运动特性类似，棘突运动在左右侧弯和左右旋转运动中也体现出了一定的对称性。基于CT扫描得到的头颈部医学图像，建立了正常人体头颈部三维动态有限元模型，包括颅骨、7节颈椎骨、第一胸椎骨骼、6个椎间盘以及连接颅骨与颈椎、连接颈椎之间的13条韧带。利用三维运动分析系统测试得到的同一受试对象的运动学数据对模型进行验证，主要包括前屈、左/右侧弯及左/右旋转5种正常的生理运动。仿真结果与试验测试数据的对比分析表明，计算仿真结果与试验测试吻合较好，所建模型合理、有效，可用于相关生物力学研究。基于均方根误差和相对均方根误差分析方法，对模型的皮质骨、松质骨、后部结构、纤维环及韧带进行的材料敏感性分析结果表明，材料弹性模量的变化对于侧弯运动的影响可以忽略，对旋转运动影响较大，而前屈运动则受到韧带弹性模量变化轻微的影响。借助核磁成像技术，对正常生理运动状态下的颈部皮肤滑移进行了评估，包括前屈及左右侧弯运动。结果表明，前屈运动时，X方向与Y方向上最大的皮肤位移发生在C2节段，分别是8.5mm和7.2mm，在Z方向C6节段最大，为9mm；侧弯运动时，X，Y，Z方向上最大的皮肤滑移均发生在C2节段上，分别为20.5mm，11mm及9.5mm。从预防融合器下沉、移位及不融合等并发症出发，确定了评估融合器防止下沉性能的主要指标为终板、融合器、皮质骨与松质骨的最大Von-Mises应力，植骨融合性能的主要指标为植骨应力。设计了5种形状的颈椎椎间融合器，基于所建立的C5-C6节段颈椎有限元模型，通过仿真其在轴向压缩、前屈、后伸、侧弯以及旋转载荷下的运动，分析了运动模式及融合器形状变化对融合器植入力学性能的影响。运动模式研究表明，轴向压缩载荷时发生下沉的风险最低，后伸运动是最有利于植骨融合的运动模式；形状研究结果表明，12-叶融合器防止下沉性能较优，而促进植骨融合器能力较优的形状则为肾形和4-叶形。基于人体颈椎椎间盘的结构力学特性，设计了具有凹槽结构的颈椎椎间融合器。通过凹槽结构的二次旋转设计，得到了防止下沉性能评价指标（终板应力、C5松质骨应力及C6松质骨应力）关于凹槽结构中心距融合器中心的位置s，凹槽结构的宽度b，以及凹槽结构的深度h的回归方程，利用该回归方程进行最优化分析得到的最优凹槽尺寸可实现降低应力22.58%~26.04%，这大大地提高了融合器防止下沉的性能，其中，开槽宽度b和深度h对植骨融合性能的影响较为显著。受马腿第三掌骨滋养小孔力学特性的启发，设计了仿生凹坑表面形态，并分别置于融合器侧面或上下表面进行融合器性能的研究。通过凹坑表面形态置于融合器侧面的正交试验设计，结果表明：防止下沉性能的最优化水平分别为，凹坑中心所在的平面与融合器中心的距离a=-2mm（+/-代表凹坑中心所在平面位于融合器中心的上/下方），凹坑的半径r=0.1mm，凹坑深径比p=1；植骨融合性能的最优化水平分别为：a=+2mm，r=0.3mm，p=1.5。通过凹坑表面形态置于融合器的上下表面的正交试验设计，得到了防止下沉性能与植骨融合性能的最优化水平为，凹坑数量12，凹坑半径0.5mm，凹坑深径比1.5。在颈椎椎间融合器的单因素（结构和表面形态）仿生研究结果基础上，运用耦合仿生原理与试验优化理论，设计了二元耦合仿生颈椎椎间融合器。仿真试验表明，凹坑表面形态置于融合器侧面的耦合仿生融合器，其防止下沉性能及植骨融合性能均较结构单元仿生显著提高；但当凹坑表面形态置于融合器的上下表面时，耦合仿生融合器的防止下沉性能及植骨融合性能却有所下降。更多还原

【Abstract】 Currently, the cervical diseases show a high incidence, professionally andyounger with the changing of people’s lifestyle; and the popularity of the vehicle alsomakes neck injury becoming a frequent injury pattern among the vehicle accidentdamage. The cervical spine biomechanical study contributes to a better understandingof the pathogenesis of cervical spine injuries, and provides a theoretical basis for theprevention and treatment of cervical spine injuries. Among of them, finite element(FE) method is optimal because of its advantages including repeatability, convenienceto perform parametric study, and cost reduction, and are increasingly applied in thehuman cervical spine biomechanics, such as cervical disease and injury mechanism,cervical surgery and internal fixation ways, the artificial prosthesis design. Becausecervical interbody fusion has the advantages of achieving immediate postoperativestability, maintaining and distracting disc height, and promoting fusion, etc., it hasbeen developed rapidly during anterior cervical surgery. But with the widespread useof it, the related complications are increasingly attracted people’s attention, such assubsidence, shift and non-fusion.In this paper, biomechanical tests of human head and neck kinematic, medicalimages of head and neck, and reverse engineering techniques were applied to studythe human cervical spine kinematic modeling. Also the bionic structure and surfacemorphology of cervical interbody fusion cage were designed, and the dual-coupledbionic cervical interbody fusion cage coupled the optimal structure and surfacemorphology was designed.Seven reflective Markers located on the human head and cervical spine weredesigned based on sports biomechanics testing methods. The motion analysis system was applied to measure5motion patterns of subject ’s head and neck under normalphysiological states including flexion, left/right lateral bending, and left/rightrotation.A three-dimensional FE model of normal human head and neck was established,containing skull,7cervical vertebrae, the first thoracic vertebra,6intervertebral disc,and13ligaments. The model was validated using the head and neck kinematic dataobtained by motion analysis device based on the same subject. Based on the rootmean square error and relative root mean square error analysis method, the predictionaccuracy of the FE head and neck model was quantified, and the material sensitivitywas also conducted to investigate the effect of material properties, including corticalbones, cancellous bones, posterior structures, fibrous annulus and ligaments underflexion, unilateral (left) lateral bending and axial rotation. Results showed that forlateral bending, there was nearly no change in model prediction results; In flexionmotion, the Young’s modulus variations of cortical bones and posterior structures alsohave nearly negligible effect on the cervical kinematics simulation results; In axialrotation, the Young’s modulus variations of cortical bones and posterior structuresalso have great impact on the cervical kinematics simulation results.In order to avoid subsidence, and improve the fusion rate, the indicators used toevaluate the interbody fusion cage performance were determined. Different shapes ofinterbody fusion cage were designed, implanted into the FE model of C5-C6segments,and simulated under several loading conditions, including axial compression, flexion,extension, lateral bending and axial rotation. Those indicators were obtained,including Von-Mises stress of the endplates, cage, adjacent vertebrae, and bone graft.The effects of different loading patterns and cage shapes on the interbody fusion cageperformances were researched by the analysis of the indicators. In the scope of thestudy, the cage of12-leaf shape has been demonstrated as the optimal one.Based on the structural characteristics of human cervical intervertebral disc, thecervical intervertebral fusion with bionic structure has been designed. Three structuralsized factors were determined, which were the distance between the center of groovestructure and the center of cage, the width of the groove structure, and the depth of the groove structure, respectively. The quadratic general spinning design was used tooptimize the bionic structural size. The regression equations between those threestructural sizes and the indicators of subsidence resistance (the stresses of endplateand cancellous bones of fifth and the sixth cervical spine) were obtained through thequadratic regression analysis method and the optimization size parameters wereobtained, respectively. The results showed that the optimized parameters for the stressof endplate and cancellous bone of fifth cervical spine were the same, also they weredifferent from which for the stress of cancellous bone of sixth cervical spine. Incontrast, the former was better.Inspired by the mechanical properties of the third metacarpal nourish of horse leg,the bionic concave surface morphology was designed and placed on the side or bothon the top and bottom of cage. Three concave size factors were determined andoptimized through the orthogonal experiment design. When the pits distributed on thecage side, the size factors was determined, which were the distance between the planepits located and the center of cage(a), the radius of pits(r), and the ratio of pit-depth topit-radius(p), respectively. For optimal subsidence resistance, the optimumcombination was the a=-2mm(+/-represented the pits located above/below the thecenter of cage), r=0.1mm，p=1; for optimal fusion rate performance, the optimumcombination was a=+2mm，r=0.3mm，p=1.5. When the pits distributed on both the topand bottom surfaces of the cage, the size factors were determined, which were thenumber of pits, the radius of pits, and the ratio of pit-depth to pit-radius, respectively.For optimal subsidence resistance and fusion rate performance of the cage, theoptimum combination was the pits’ number of12, radius of0.5mm, and ratio ofpit-depth to pit-radius of1.5.With the single-factor bionic results of cervical fusion cage, based on thecoupling bionic theory, the dual-coupled bionic cervical interbody fusion cage wasdesigned. The results showed, the subsidence resistance and fusion rate performanceof the coupling bionic fusion cage have been improved when the pits distributed onthe cage side. While, the subsidence resistance and fusion rate performance of thecoupling bionic fusion cage have been decreased when the pits distributed on both thetop and bottom of the cage.更多还原