下颌骨髁突矢状骨折内固定及骨折愈合进程中的三维有限元分析

发布时间：2019-06-10 10:38

【摘要】：目的：基于CT图像利用反求工程方法建立II型下颌骨髁突矢状骨折、不同坚固内固定技术及骨折愈合进程中的几何模型和有限元模型，以模拟计算不同内固定方式下微型钛板的应力分布，从而为下颌骨髁突矢状骨折坚固内固定提供理论依据和临床指导。方法：运用反求工程软件、CAD软件和有限元软件建立下颌骨的三维有限元模型。在模型上进行咬合加载，分析II型髁突矢状骨折不同内固定方式下，不同内固定物的应力分布。通过比较不同愈合时期骨折游离端的最大转角、最大位移，钛板所受的最大等效应力，以此评价不同内固定方式的生物力学效果。结果：本实验建立了高几何相似性和力学相似性的下颌骨皮质骨和松质骨三维有限元模型，在此模型的基础上，建立了右侧髁突Ⅱ型矢状骨折不同内固定方式的有限元模型：（1）一枚四孔“一”字形微型钛板固定，共有30489个节点、173677个单元；（2）两枚四孔“一”字形微型钛板固定（二者平行），，共有36711个节点、187199个单元；（3）一枚四孔“一”字形微型钛板，一枚四孔“L”形微型钛板同时固定，共有31427个节点、198676个单元；（4）两枚四孔“L”形微型钛板固定（成角固定），共有41407个节点、211113个单元。以及其不同愈合时期（术后当天、第四周、第八周、第十二周）的有限元模型。术后当天四种内固定方法（1个“一”字形、2个“一”字形、1个“一”字形+1个“L”形、2个“L”形）骨折游离端位移依次为0.879mm、0.883mm、0.887mm、0.877mm；骨折游离端最大转角依次为0.038°、0.020°、0.017°、0.018°；钛板上最大等效应力依次为：2297MPa、530.324MPa、897.06MPa、600.61MPa。术后第四周四种内固定方法骨折游离端位移依次为0.877mm、0.862mm、0.868mm、0.859mm；骨折游离端最大转角依次为0.039°、0.028°、0.032°、0.045°；钛板上最大等效应力依次为：556.081MPa、445.17MPa、532.523MPa、468.725MPa。术后第八周四种内固定方法骨折游离端位移依次为0.862mm、0.862mm、0.868mm、0.859mm；骨折游离端最大转角依次为0.028°、0.028°、0.028°、0.036°；钛板上最大等效应力依次为：317.091MPa、443.71MPa、528.108MPa、465.505MPa。术后第十二周四种内固定方法骨折游离端位移依次为0.862mm、0.862mm、0.868mm、0.859mm；骨折游离端最大转角依次为0.025°、0.028°、0.028°、0.046°；钛板上最大等效应力依次为：239.631MPa、443.294MPa、527.404MPa、463.686MPa。结论：从力学效果分布均匀角度看，采用两个“一”字形钛板固定髁突骨折可为下颌骨系统提供较稳定的应力分布，次之为一个“一”字形与一个“L”形钛板的组合；从骨折断端位移角度看，两个“L”形钛板提供稳定的固位，其次为两个“一”字形钛板。不论何种固定方式，在骨折断层明显有压应力存在，坚固内固定方法对于髁突矢状骨折有着明显的治疗作用。
[Abstract]:Objective: to establish the geometric model and finite element model of type II mandibular condylar sagittal fracture, different rigid internal fixation techniques and fracture healing process based on CT image. The stress distribution of micro titanium plate under different internal fixation methods was simulated and calculated, which provided theoretical basis and clinical guidance for rigid internal fixation of mandibular condylar sagittal fracture. Methods: the three-dimensional finite element model of mandibular was established by reverse engineering software, CAD software and finite element software. The stress distribution of type II condylar sagittal fracture under different internal fixation modes was analyzed by occlusal loading on the model. The biomechanical effects of different internal fixation methods were evaluated by comparing the maximum rotation angle, maximum displacement and maximum equivalent stress of titanium plate at the free end of fracture in different healing periods. Results: a three-dimensional finite element model of mandibular cortical bone and cancellous bone with high geometric and mechanical similarity was established. The finite element models of different internal fixation methods for type II sagittal fracture of the right condyle were established: (1) A four-hole "one" shaped miniature titanium plate was fixed with 30489 nodes and 173677 elements; (2) two four-hole "one" shaped miniature titanium plates are fixed (parallel to each other), with a total of 36711 nodes and 187199 units; (3) A four-hole "one" shaped miniature titanium plate and a four-hole "L" miniature titanium plate are fixed at the same time, with a total of 31427 nodes and 198676 units; (4) two four-hole "L" miniature titanium plates are fixed (angled fixed) with 41407 nodes and 211113 elements. And the finite element models of different healing periods (4 weeks, 4 weeks, 8 weeks, 12 weeks after operation). On the day after operation, the free end displacement of four internal fixation methods (1 "one" shape, 2 "one" shape, 1 "one" L "shape, 2" L "shape) was 0.879mm, 0.883 mm, 0.887 mm, 0.877 mm, respectively. The maximum rotation angle of the free end of the fracture was 0.038 掳, 0.020 掳, 0.017 掳, 0.018 掳, and the maximum equivalent stress on the titanium plate was 2297 MPA, 530.324 MPA, 897.06 MPA, 600.61 MPA, respectively. In the fourth week after operation, the displacement of the free end of the fracture was 0.877mm, 0.862mm, 0.868mm, 0.859mm, and the maximum rotation angle of the fracture was 0.039 掳, 0.028 掳, 0.032 掳and 0.045 掳, respectively. The maximum equivalent stress on titanium plate is 556.081MPA, 445.17MPa, 532.523MPA, 468.725MPA. In the eighth week after operation, the displacement of the free end of the fracture was 0.862 mm, 0.862 mm, 0.868 mm, 0.859 mm, and the maximum rotation angle of the free end of the fracture was 0.028 掳, 0.028 掳, 0.028 掳, 0.036 掳, respectively. The maximum equivalent stress on titanium plate is 317.091 MPA, 443.71 MPA, 528.108 MPA, 465.505 MPA. At the 12th week after operation, the displacement of free end of fracture was 0.862 mm, 0.862 mm, 0.868 mm, 0.859 mm, and the maximum rotation angle of free end of fracture was 0.025 掳, 0.028 掳, 0.028 掳, 0.046 掳, respectively. The maximum equivalent stress on titanium plate is 239.631 MPA, 443.294 MPA, 527.404 MPA, 463.686 MPA. Conclusion: from the point of view of uniform distribution of mechanical effect, the fixation of condylar fracture with two "one" shaped titanium plates can provide a stable stress distribution for the mandibular system, followed by the combination of one "shaped titanium plate and one" L "titanium plate. From the point of view of fracture displacement, two "L" titanium plates provide stable retention, followed by two "one" shaped titanium plates. No matter what kind of fixation, the compression stress exists obviously in the fracture section, and the rigid internal fixation method has obvious therapeutic effect on the sagittal fracture of condyle.
【学位授予单位】：宁夏医科大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：R782.4

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