改良股骨近端髓内钉固定Evans Ⅳ型股骨转子间骨折的有限元分析

发布时间：2018-07-01 10:12

本文选题：股骨转子间骨折 + 有限元分析　；参考：《广州中医药大学》2017年博士论文

【摘要】：目的:随着生物力学、材料学的发展,股骨转子间骨折的治疗也取得了许多进步,多种多样的内固定器械随之产生,髓内钉固定成为了目前股骨转子间骨折的治疗主流,但仍无法避免内固定失败的发生。回顾性分析股骨转子间骨折髓内钉固定术后的患者基本临床资料、骨质疏松评级、骨折复位质量、尖顶距等资料,探讨股骨转子间骨折髓内钉固定后发生内固定失败的危险因素。有限元分析已被用于内固定器械的力学性能评价,指导医疗器械的设计和改造。本研究根据股骨近端"三角固定"理论设计了改良股骨近端髓内钉。在PFNA-Ⅱ的基础上调整螺旋刀片与主钉的角度,同时增加1枚近端抗张力螺钉。通过有限元分析方法比较生理载荷状态下改良股骨近端髓内钉和PFNA-Ⅱ固定Evans Ⅳ型不稳定型股骨转子间骨折的生物力学性能,检验改良股骨近端髓内钉设计的合理性,为新器械的临床应用提供理论依据及研究思路。方法:选取广州中医药大学第一附属医院诊断为股骨转子间骨折并接受闭合复位髓内钉固定的患者,设定纳入标准和排除标准。收集患者年龄、性别、骨折患侧、骨折类型、复位质量、内固定种类、尖顶距、内固定失败等临床资料。采用卡方检验等方法比较内固定失败组和内固定未失败组患者的临床资料之间的差异,通过二元回归的方法了解骨折内固定失败的危险因素。选取一名健康老年男性志愿者,用螺旋CT对其右侧股骨进行全段薄层扫描。CT影像数据导入Mimics 14.1软件,根据不同组织灰度值的差异,通过阈值化及像素修补、区域增长和消除孤立点等处理,分离皮质骨、松质骨和骨髓腔,利用三维模型生成功能生成股骨中上段三维模型。将股骨中上段三维模型导入逆向工程软件Geomagic Studio 10.0进行光滑处理网格划分。将股骨模型导入Abaqus 12.0进行载荷预实验,验证本研究的模型可靠有效。再将股骨模型导入到Solidwork2010软件中模拟EvansⅣV型骨折进行截骨建立Evans Ⅳ型股骨转子间不稳定型骨折模型。在SolidWorks 2010软件中根据PFNA-Ⅱ髓内钉数据尺寸三维重建PFNA-Ⅱ和改良股骨近端髓内钉得到数字模型。将Evans Ⅳ型股骨转子间骨折模型及两种髓内钉模型导入SolidWorks 2010中进行装配,生成改良股骨近端髓内钉和PFNA-Ⅱ内固定后的模型。髓内钉在股骨中的位置以辛迪思所提供手术操作标准为参考,螺旋刀片位于股骨头中下靠后位置。然后将骨折内固定模型导入到限元分析软件Abaqus 12.0进行处理分析。参照参考文献中的材料赋值、边界条件和加载条件,模拟成人双足站立位和步态周期关节承载峰值时刻两种受力情况进行静态加载和动态加载有限元分析。得到两种内固定模型在相同载荷下的内固定物的应力分布及应力峰值、股骨的应力分布及应力值、内固定模型的位移情况及位移值,比较分析两种不同髓内钉固定老年不稳定型股骨转子间骨折的生物力学性能。结果:共纳入107例股骨转子间骨折髓内钉闭合复位固定的患者,男性45例,女性62例,平均年龄为75.07±6.16岁(65岁-90岁)。其中内固定失败组10例,内固定未失败组97例。内固定失败组和内固定未失败组患者在性别比例、骨折患侧、骨折分型、内固定方式、骨质疏松方面的差异无统计学意义(P0.05)。两组患者在年龄、骨折复位质量、尖顶距方面的差异具有统计学意义(P0.05)。二元回归显示尖顶距大于25mm是发生股骨转子间骨折髓内钉内固定失败的唯一危险因素。建立老年Evans Ⅳ型股骨转子间骨折的三维有限元模型、改良股骨近端髓内钉及PFAN-Ⅱ两种髓内钉固定股骨转子间骨折后的三维有限元模型。在两种生理载荷状态下,两种内固定模型的应力集中均位于头颈螺钉与主钉交界部位。改良股骨近端髓内钉的内固定应力值大于PFNA-Ⅱ,静态加载和动态加载情况下两者的应力峰值分别为228.0Mpa、214.4Mpa和618.3Mpa、575.4Mpa。改良股骨近端髓内钉固定模型的股骨应力峰值大于PFNA-Ⅱ固定模型的股骨应力峰值,静态加载和动态加载情况下股骨的应力峰值分别为113.4Mpa、95.8Mpa和150.8Mpa、125.8Mpa。两种加载模式下改良股骨近端髓内钉固定模型的位移值较小于PFNA-Ⅱ组,分别为5.01mm、5.37mm和5.18mm、5.59mm。结论:股骨转子间骨折髓内钉固定术后有较高的内固定失败发生率。高龄患者、骨折复位不佳、尖顶距大于25mm时出现内固定失败的风险较高。尖顶距是预测髓内钉内固定失败的重要因素。在临床手术操作中需要注意控制头颈螺钉的尖顶距小于25mm,以降低内固定失败的可能。有限元分析方法可以很好的模拟和验证新器械的生物力学性能,具有力学性能测试全面、可重复性好等优点。对于不稳定型Evans Ⅳ型股骨转子间骨折,改良股骨近端髓内钉在固定不稳定型股骨转子间骨折时具有较好的稳定性。考虑到临床实际情况,本研究中抗张力螺钉与螺旋刀片之间未产生接触,导致抗力螺钉、螺旋刀片、髓内钉主钉三者之间无法形成闭合三角形结构,上方的抗张力螺钉由于更加接近受力点而承受较高应力存在导致应力峰值较高。有限元分析是对实际情况的一种模拟分析,是将复杂问题简单化,仍需要和传统的离体生物力学实验相结合进行验证,从而为改良股骨近端髓内钉进行正确的评价。
[Abstract]:Objective: with the development of biomechanics and material science, many advances have been made in the treatment of intertrochanteric fracture of the femur, and a variety of internal fixation instruments are produced. Intramedullary nail fixation has become the mainstream of the treatment of intertrochanteric fracture of the femur, but it is still impossible to avoid the failure of internal fixation. The basic clinical data, the rating of osteoporosis, the quality of fracture reduction, the spires and so on were used to investigate the risk factors of internal fixation failure after intramedullary nail fixation of intertrochanteric fractures. Finite element analysis has been used to evaluate the mechanical properties of internal fixation instruments and guide the design and transformation of medical instruments. The proximal intramedullary nail of the femur was designed by the "triangular fixation" theory. On the basis of PFNA- II, the angle of the spiral blade and the main nail were adjusted and 1 proximal tension screws were added. The modified femoral proximal intramedullary nailing and the PFNA- II fixed Evans IV unstable femur rotor were compared by the finite element analysis. The biomechanical properties of intervertebral fractures, the rationality of the modified intramedullary nail design of the femur, and the theoretical basis and research ideas for the clinical application of the new instruments. Methods: selected patients who were diagnosed as intertrochanteric fractures in the First Affiliated Hospital of Guangzhou University of Chinese Medicine and received closed reduction and intramedullary nail fixation were set into standards and exclusion. Criteria. The clinical data of patients' age, sex, fracture side, fracture type, reduction quality, internal fixation type, spires, internal fixation failure were used to compare the difference of clinical data between the internal fixation failure group and the internal fixation unsuccessful group by the chi square test, and the two yuan regression method was used to understand the failure of the internal fixation. The risk factors. A healthy old male volunteer was selected and the.CT image data of the right femur were scanned by spiral CT into Mimics 14.1 software. According to the difference of the gray value of different tissues, the cortical bone, cancellous bone and bone marrow cavity were separated by threshold and pixel repair, regional growth and elimination of isolated points. The three-dimensional model of the three dimensional model is generated to generate the three-dimensional model of the middle and upper part of the femur. The three-dimensional model of the middle and upper part of the femur is introduced into the reverse engineering software Geomagic Studio 10 for smoothing the mesh. The femur model is introduced into the Abaqus 12 for the load pre experiment to verify the reliability and effectiveness of the model. Then the femur model is introduced into the Solidwork2010 soft. A model of unstable intertrochanteric fracture of type Evans IV was established by simulating Evans IV V fracture. In SolidWorks 2010 software, a digital model was obtained by three-dimensional reconstruction of PFNA- II with PFNA- II intramedullary nail data size and modified proximal femoral intramedullary nail. The model of Evans IV interfemoral fracture and two intramedullary nail models were used. SolidWorks 2010 was introduced into the assembly to produce a modified model of the modified proximal femoral nail and PFNA- II internal fixation. The position of the intramedullary nail in the femur was referenced by the operating standard provided by Cindy. The spiral blade was located at the back position of the femoral head. Then the internal fixation model was introduced into the finite element analysis software Abaqus 12. According to the material assignment, boundary conditions and loading conditions in the reference literature, the static loading and dynamic loading finite element analysis of two kinds of stress conditions of the adult bipedal standing position and the gait periodic joint bearing peak load are simulated. The stress distribution and stress of the internal fixtures of the two internal fixed models under the same load are obtained. Peak value, stress distribution and stress value of the femur, displacement and displacement value of internal fixation model, compare and analyze the biomechanical properties of two different intramedullary nails in the fixation of unstable intertrochanteric fracture of the femur. Results: 107 cases of intertrochanteric fracture of femur were included, 45 cases in male, 62 in women, and average year. The age was 75.07 + 6.16 years (65 years old -90 years). Among them, there were 10 cases of internal fixation failure group and 97 cases with internal fixation without failure. There was no statistically significant difference in the sex ratio, fracture side, fracture classification, internal fixation and osteoporosis (P0.05). The two groups were in age, fracture reduction quality, and spires in the two groups. The difference in distance was statistically significant (P0.05). The two yuan regression showed that the spel distance greater than 25mm was the only risk factor for the failure of intramedullary nail internal fixation for intertrochanteric fracture of the femur. A three-dimensional finite element model of the aged Evans IV intertrochanteric fracture of the femur was established, and the modified femoral intramedullary nailing and the two intramedullary nailing of the femoral intertrochanteric were fixed for the fixation of the femur. The three-dimensional finite element model after intervertebral fracture. Under two physiological loads, the stress concentration of the two internal fixation models is located at the junction between the head and neck screw and the main nail. The internal fixation stress of the modified proximal intramedullary nail of the femur is greater than that of PFNA- II. The stress peaks of both static loading and dynamic loading are 228.0Mpa, 214.4Mpa, respectively. The peak femur stress peak of the modified femoral proximal intramedullary nail fixation model was greater than that of the PFNA- II fixed model. The peak stress of the femur under static loading and dynamic loading was 113.4Mpa, 95.8Mpa and 150.8Mpa, and the displacement of the femoral proximal intramedullary nail fixation model under the two loading modes of the femur under static loading and dynamic loading, respectively. The displacement of the femoral proximal femoral nail fixation model under static loading and dynamic loading was the displacement of the femoral proximal intramedullary nail fixation model under the static loading and the dynamic loading conditions, respectively, under the static loading and the dynamic loading conditions of the femur under the static loading and dynamic loading conditions of the femur. The value is less than PFNA- II group, 5.01mm, 5.37mm and 5.18mm, respectively, 5.59mm. conclusion: after intramedullary nail fixation of intertrochanteric fracture, there is a higher failure rate of internal fixation. The risk of internal fixation failure when the fracture reduction is poor and the spires greater than 25mm is higher in the elderly patients. The apical distance is an important factor to predict the failure of intramedullary nail internal fixation. In clinical operation, it is necessary to pay attention to control the tip of head and neck screw less than 25mm to reduce the possibility of failure of internal fixation. The finite element analysis method can well simulate and verify the biomechanical properties of the new apparatus. It has the advantages of comprehensive mechanical test and good repeatability. For unstable type Evans IV type femur intertrochanteric bone The modified proximal femur intramedullary nail has better stability when the intertrochanteric fracture of the femur is fixed. Considering the clinical practice, there is no contact between the tension screw and the spiral blade in this study, which leads to the failure to form a closed triangular structure between the resistance screws, the spiral blade and the intramedullary nail main nail, and the resistance above is not formed between the three. The finite element analysis is an analogue analysis of the actual situation, which is a simplification of the complicated problems and still needs to be combined with the traditional biomechanical experiments to verify the correct evaluation of the improved proximal intramedullary nail for the femur.
【学位授予单位】：广州中医药大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：R687.3

【参考文献】