不同数量和排列方式的空心拉力螺钉治疗股骨颈骨折的有限元分析

发布时间：2018-04-09 09:07

本文选题：股骨颈骨折　切入点：有限元分析　出处：《河北医科大学》2017年硕士论文

【摘要】：目的:1建立股骨近端的有限元模型。2利用三维绘图软件分别绘制3种不同Pauwels分型的股骨颈骨折模型及4种不同类型的股骨颈内固定模型:分别为“正三角形”排列的三枚空心拉力螺钉模型;“倒三角形”排列的三枚空心拉力螺钉模型;“矩形”排列的四枚空心拉力螺钉模型;“菱形”排列的四枚空心拉力螺钉模型。3利用Ansys软件,比较分析4种不同空心拉力螺钉内固定方式对3种不同Pauwels分型的股骨颈骨折断端及内固定物的应力分布、位移大小。综合评价每种空心拉力螺钉内固定的固定特点。通过比较分析不同内固定方式生物力学的稳定性,为临床的应用提供理论依据及指导性建议。方法:1不同Pauwels分型的股骨颈骨折的有限元模型的构建:通过X线检查排除髋部的骨折、肿瘤及畸形等骨质破坏的存在。采用Somatom Sensatim 64排螺旋CT扫描正常人股骨近端,自股骨头上方至小转子下方,扫描方法为电压:120k V,电流200m A,扫描层厚1mm,层间距1mm,将图像存储为DICOM格式,共获得250个DICOM图像数据,并导入个人计算机的Mimics 14.0软件中,确定阈值后,构建出正常骨头的三维模型。将以上模型以STL格式导入到自动化逆向工程软件Geomagic Studio 12.0中,对模型进行光顺、平滑、裁剪、偏移、布尔减运算等处理,分别得到更为精细的模型文件,从而能够得到更为精细、精确的股骨颈模型文件,结果以Iges格式输出保存。将Geomagic Studio中生成的Iges格式文件导入Solid Works软件中,进行实体重构,切割骨折线,分别为30°,50°,及70°。从而生成实体模型。2内固定模型的构建:在Solid Works软件中构建4种不同空心拉力螺钉排列方式的内固定模型,分别为:a:“正三角”形排列的三枚空心拉力螺钉模型;b:“倒三角”形排列的三枚空心拉力螺钉模型;c:矩形排列的四枚空心拉力螺钉模型;d:菱形排列的四枚空心拉力螺钉模型。其中,空心拉力螺钉全长100mm,直径6.5mm,螺纹、中空部分忽略不计。所构建的空心拉力螺钉与股骨相互定位,完成空心钉植入,并应用布尔运算删除空心拉力螺钉处骨骼。生成节点和单元后导入有限元分析软件Ansys(ANSYS公司,美国)进行处理分析。3骨折内固定有限元模型的材料赋值、边界条件及加载:将以上模型导入模拟软件Ansys Workbench中,继而导入Mimics软件中根据灰度赋予不同的材料属性,并重新导入Ansys中施加边界条件和约束,模拟骨头受力情况,忽略关节之间的摩擦力,忽略关节软骨,简化处理肌肉及肌腱的应力作用。并假设骨折面完全断裂并处于完全接触状态,骨折断端接触面的摩擦力为0.2,将股骨近端有限元模型的小转子下缘全部节点的自由度约束为0作为边界条件;远端在x、y、z轴上的位移为0。采用目前常用的简化模型,仅考虑髋臼窝作用于股骨头上的力及大转子邻近的外展肌力(臀中肌与梨状肌)及股外侧肌作为有限元分析的外载荷,给予轴向600N应力,沿轴向向下,平均作用于髋臼和股骨头的接触面,从而模拟受力,进行运算。4评价指标,通过3种指标对4种内固定模型(a~d)的力学性能进行综合分析:㈠内固定物的应力分布及应力峰值;㈡股骨头及内固定的位移和峰值;㈢头侧骨折断端的应力分布及应力峰值。结果:通过获得正常人股骨近端的CT扫描数据,利用Mimics、Geomagic Studio等软件,建立股骨颈骨折的有限元模型,这种方法可行性高,且建模速度快,对人体损伤极小。有限元方法是生物力学研究的一种理论方法。通过赋予其各种组织、结构的材料属性,能够模拟出不同结构的几何模型,并且能很好的反映其生物力学特性。所以,可以成为标本生物力学研究很好的补充。对于不同Pauwels分型,最优的置钉方式是菱形排列的四枚空心拉力螺钉。对于Pauwels I型股骨颈骨折,4种模型的应力峰值分别为:a:46.382MPa;b:32.159MPa;c:43.985 MPa:d:24.342 MPa。头侧股骨颈骨折断端应力峰值分别为:a:5.840 MPa;b:7.440 MPa:c:3.731 MPa:d:6.311 MPa。股骨头处位移峰值为:a:0.610mm;b:0.608mm;c:0.598mm:d:0.595mm;对于Pauwels II型股骨颈骨折,4种模型的应力峰值分别为:a:46.763 MPa;b:39.979 MPa;c:49.619 MPa:d:25.692 MPa。头侧股骨颈骨折断端应力峰值分别为:a:4.971 MPa;b:7.332 MPa:c:3.161 MPa:d:5.734 MPa。股骨头处位移峰值为:a:0.634mm;b:0.635mm;c:0.622 mm:d:0.631mm;对于Pauwels III型股骨颈骨折,4种模型的应力峰值分别为:a:51.432 MPa;b:39.477 MPa;c:51.515 MPa:d:26.949 MPa。头侧股骨颈骨折断端应力峰值分别为:a:6.163 MPa;b:10.070 MPa:c:5.257 MPa:d:9.552 MPa。股骨头处位移峰值为:a:0.662mm;b:0.654mm;c:0.644 mm:d:0.644mm。结论:通过有限元分析得出:对于不同Pauwels分型的股骨颈骨折,矩形、菱形四枚拉力螺钉固定的骨折在压力作用下产生的移位小于正、倒三角拉力螺钉固定的骨折,可有效稳定骨折断端;相比于正、倒三角及矩形四枚拉力螺钉,菱形四枚拉力螺钉结构具有更大的应力分散作用。既能够达到较为稳定的生物力学稳定性,又能够有效防止股骨颈短缩。
[Abstract]:Objective: to establish 1 finite element model of proximal femur.2 using three-dimensional drawing software were drawn 3 different types of Pauwels femoral neck fracture model and 4 kinds of different types of femoral neck fracture model: as the "triangle" with the three cannulated screw model; inverted triangular arrangement of three hollow screw model; "rectangular" with the four cannulated screw model; "diamond" arrangement of four cannulated screws fixation model using.3 Ansys software, a comparative analysis of the broken ends and internal stress distribution, the displacement of 4 different cannulated screws internal fixation methods of the 3 different Pauwels types of femur fracture of the neck. A comprehensive evaluation of characteristics of fixed fixed each hollow screw. Through comparative analysis of different internal fixation biomechanical stability, provide a theoretical basis and guidance for clinical application On the construction of finite element model. Methods: 1 different Pauwels types of femoral neck fracture: through X-ray examination to exclude hip fractures, tumors and malformations of bone destruction. Using Somatom Sensatim with 64 slice spiral CT scan of normal proximal femoral head, from above to below the small rotor, scanning method voltage: 120K V 200m, current A, slice thickness 1mm, spacing 1mm, images will be stored as DICOM format, received a total of 250 DICOM image data, and import of personal computer software Mimics 14, to determine the threshold, to construct three dimensional model of normal bone. The above model in STL format into automatic reverse engineering software Geomagic Studio 12, smoothing, smoothing, clipping, offset on the model, Boolean subtraction processing, respectively, to obtain more precise model files, which can be more precise, accurate femoral neck model file, The results in Iges format output. The Iges format file into Solid Works software to generate Geomagic Studio in solid reconstruction, cutting the fracture line was 30 degrees, 50 degrees, and 70 degrees. To build a solid model is generated by.2 internal fixation model: construction arrangement of 4 kinds of hollow screw internal fixed model in Solid Works software respectively: a: triangle shaped arrangement of three cannulated screws fixation model; b: inverted triangle shaped arrangement of three cannulated screw model; c: rectangular array of four cannulated screws fixation model; d: diamond arranged four cannulated screws fixation model. The hollow screw, length 100mm, diameter 6.5mm, thread, the hollow part is negligible. The hollow screw and femur constructed by mutual positioning, complete hollow screw implantation, and the application of Boolean operation to remove bones. Hollow tension screw generation The nodes and elements into finite element analysis software Ansys (ANSYS company, USA) for analysis and processing of.3 internal fixation of fracture finite element model of the material assignment, boundary conditions and loading: the above model into the simulation software Ansys Workbench, and then import the Mimics software based on the gray with different material properties, and re applied into Ansys the boundary conditions and constraints, simulated bone stress, neglecting friction between joints, ignoring the articular cartilage, simplify the stress treatment of muscle and tendon. It is assumed that the fracture surface and complete rupture of the state of complete contact state, fracture broken end friction contact surface is 0.2 degrees of freedom constraint small rotor proximal femur finite element the lower edge of the model of all nodes is 0 as the boundary condition; the distal in X, y, Z axis displacement for 0. of the current commonly used simplified model, considering only the acetabular fossa on the femoral Abductor nearby and the forces on the rotor (piriformis muscle and gluteus medius) and vastus lateralis muscle as the load of finite element analysis, given the 600N axial stress along the axial direction, the contact effect on the average acetabular and femoral head surface to simulate the stress, calculate.4 evaluation index. Of the 4 kinds of internal fixation model by 3 indexes (a~d) to make a comprehensive analysis of the mechanical properties: the internal fixation of the stress distribution and the peak value of two; internal fixation of femoral head and the displacement and the peak; three head side of the fracture stress distribution and the peak value of the broken end. Results: by CT scan data the normal person, the proximal femur using Mimics Geomagic Studio software, establish the finite element model of femoral neck fracture, this method is highly feasible, and fast modeling speed, minimal damage to human bodies. The finite element method is a theoretical method of biomechanical research. By giving the various groups Fabric, material property, can simulate the geometric models of different structures, and can reflect the biomechanical characteristics very well. So, can complement the biomechanical well studied. For different Pauwels types, the way is the optimal arrangement of the diamond nail four cannulated screws fixation for femoral I Pauwels. Fracture of the neck, the peak stress of 4 models respectively: a:46.382MPa; b:32.159MPa; the broken end of the peak stress were c:43.985 MPa:d:24.342 MPa., head of a femoral neck fracture: a:5.840 MPa; b:7.440 MPa:c:3.731 MPa:d:6.311 MPa. femoral head displacement peak: a:0.610mm; b:0.608mm; c:0.598mm:d:0.595mm; for Pauwels type II femoral neck fracture, stress peak the 4 models were: a:46.763 MPa; b:39.979 MPa; the broken end of the peak stress were c:49.619 MPa:d:25.692 MPa., head of a femoral neck fracture: a: 4.971 MPa; b:7.332 MPa:c:3.16 1 MPa:d:5.734 MPa. femoral head displacement peak: a:0.634mm; b:0.635mm; c:0.622 mm:d:0.631mm; Pauwels III for femoral neck fracture, the stress peak of 4 models respectively: a:51.432 MPa; b:39.477 MPa; the broken end of the peak stress were c:51.515 MPa:d:26.949 MPa., head of a femoral neck fracture: a:6.163 MPa; b:10.070 MPa:c:5.257 MPa:d:9.552 MPa. the femoral head displacement peak: a:0.662mm; b:0.654mm; c:0.644 mm:d:0.644mm. conclusion: the finite element analysis for different Pauwels types of femoral neck fracture, rectangle, diamond four lag screws fracture produced under pressure is lower than the normal displacement, inverted triangle screw fixation of fractures can effectively stabilize fracture compared with the end; Yu Zheng, inverted triangle and rectangle four screw, four screw diamond structure has bigger stress dispersion effect. Both can achieve a relatively stable The stability of the biomechanics can also effectively prevent the short necking of the neck of the femur.

【学位授予单位】：河北医科大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R687.3

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