【作者】 曹李华；

【导师】 张朝跃；

【作者基本信息】 中南大学 ， 外科学， 2010， 硕士

【摘要】 目的：本文通过有限元法建立寰椎后弓骨折的三维有限元模型并模拟内固定术后模型的生物力学进行分析和验证,以便对临床进一步诊治寰椎后弓骨折提供一定的理论依据。方法：(1)获取健康成年男性的寰枢椎复合体CT扫描的计算机数字图像数据,利用Mimics软件将图像坐标数据转换成ASCII格式的点云数据,并利用CATIA软件对点云进行处理,随后通过Geomagic studio、Catia建立寰枢椎几何模型,然后导入有限元处理软件Hypermesh、Ls-dyna建立枕颈区有限元模型,并确定模型加载的边界条件和加载方式。(2)将健康寰枢椎模型中的C2椎体下表面定位,模拟颈椎大幅度的俯仰运动、轴向大载荷加载,了解寰椎正常模型和骨折模型在各种工况下的受力情况。(3)对于骨折模型,按照后路钛板、螺钉内固定手术进行处理,模拟颈椎的正常动作检验手术的有效性。结果：(1)所建上颈椎的有限元模型外形逼真,几何相似性好,正常模型共包含35719个节点,8797个单元,骨折模型共包含38451个节点,9782个单元；(2)应用上颈椎模型在枕骨加载面压力,模拟头颅位于中立、前屈、后伸位时,寰椎前弓受力最大,其次是后弓及侧块；(3)单独应用寰椎模型,直接在寰椎上关节面加载力,模拟头颅在中立、前屈、后伸位时寰椎最大应力集中于前弓,次级应力集中区域为侧块及后弓与侧块的交界处；直接在后弓加载力模拟头部过度后伸时,最大应力集中于后弓与侧块交界处。(4)对于寰椎后弓骨折模型,在模拟头颅中立、前屈、后伸位时在钛板、螺钉处存在应力集中,但仍在理想范围之内。结论：1、所建模型外观逼真符合实验要求,所得数据和图像可以重复使用。2、在模型上可以施加确切模拟和理想化的边界载荷条件,从而验证骨折的受伤机理。3、内固定术后模型验证寰椎后弓骨折内固定术后钛板和螺钉处存在应力集中,但是仍在理想范围之内,证明该手术方法是可靠的。更多还原

【Abstract】 Objective:In this paper, finite element method fracture of the posterior arch of atlas three-dimensional finite element model and simulate the internal fixation biomechanical model analysis and verification, in order to further diagnosis and treatment of clinical fractures of the posterior arch of atlas provide a theoretical basis.Methods:(1) The coordinate data of healthy men’s atlas was got by SCT. Then the picture data was converted to ASCII cloudy point by MIMICS. The point data was deal with CATIA software. GEOMAGIC STUDIO and CATIA were used to establish geometry model. The pre-post was carried out by HYPERMESH and LS-DYNA. The finite model was loaded and validated by some test data. (2) The underside of C2 in the healthy atlantoaxial model was fixed, and the significant movement of neck was simulated such as pitching, axial large load, to understand atlantoaxial model under the condition of various movements and forces. (3) Fracture model is treated with internal fixation operation to simulate the normal cervical spine motion, and thus test the feasibility of surgery.Results:1) The established finite element model of upper cervical spine, which contains a total of 35719 nodes,8797 elements, has accurate appearance and good geometric similarity; 2) Using upper cervical spine model (C0-C2) and exerting surface pressure on occipital simulates the situation that when head is in neutral, anteflexion, extension positions, atlas anterior arch is acted by the largest force, followed by the posterior arch and lateral mass; 3) Using atlas model alone and exerting force to upper joint surface of atlas simulates the situation that when head is in neutral, anteflexion, extension positions, atlas maximum stress concentrates on anterior arch and secondary stress concertrates on lateral mass and the junction between posterior arch and lateral mass; directly exerting force to posterior arch simulates the situation that when head is in the position of over-extension, the maximum stress concentrates on the junction between posterior arch and interal mass.4) Finite element analysis of internal fixation model after simulated surgery to the model of atlas posterior arch fracture concludes that when simulating the situation that head is in neutral, anteflexion, extension positions, there is stress concentration in position of screw, but in the ideal range.Conclusion:1, the model looks realistic with the experimental requirements, the data and images can be reused.2, the model can be applied accurately simulated and idealized boundary load conditions, which verifies the fracture mechanism of injury.3, model validation after internal fixation of posterior arch of atlas fracture fixation plate and screws there is stress concentration, but still within the ideal range, show that the surgical method is reliable.更多还原