带锁髓内钉棒槌形高螺纹锁钉的力学性能研究

发布时间：2018-12-30 15:00

【摘要】：胫骨骨折是一种较为常见的长管状骨折,髓内钉固定术是其手术治疗的主要方法之一。目前临床上应用的带锁髓内钉大都为静力性固定,存在着较高的应力遮挡效应和锁钉疲劳断裂等缺陷,这将影响骨折的愈合并增加患者的痛苦,阻碍了其临床应用的发展,因而寻求一种既能使骨折断端固定可靠,又能使消除应力遮挡效应的髓内钉及锁钉是临床需要迫切解决的一个问题。为此,课题组设计出了带锁髓内钉的“棒槌形”高螺纹锁钉,期望它能有效地降低临床上的锁钉断裂风险,实现髓内钉静动自动转变以消除高应力遮挡效应,给骨折的愈合创造一个较好的力学环境。然而,“棒槌形”高螺纹锁钉的力学性能还需通过一系列分析研究。目的:研究“棒槌形”高螺纹锁钉的力学性能,验证其力学优势,为其临床应用提供理论基础和科学依据。方法:以国人胫骨髓腔测量数据为依据,按跨距30mm、40mm、50mm分为A、B、C三组,根据锁钉在骨折固定时的实际受力情形设计出相应的试验夹具,并按跨距加工出所需的试验用锁钉,通过三点弯曲力学测试检测其弯曲强度并与通用锁钉进行对照。以CT扫描获取的胫骨二维断层数据为基础,运用Mimics、Geomagic Studio等软件构造胫骨三维实体模型,利用Pro/E软件建立髓内钉和“棒槌形”锁钉及通用锁钉模型并与胫骨三维实体模型装配,导入ANSYS软件构造两种不同锁钉的带锁髓内钉固定胫骨骨折,模拟双足站立、单足站立、慢步行走及扭转等状况下胫骨受力进行有限元分析。结果:力学测试结果显示,在弹性应变范围内不同跨距三组中“棒槌形”锁钉的平均最大弯曲载荷均高于通用锁钉的平均最大弯曲载荷,其中A、B、C三组“棒槌形”锁钉的平均最大弯曲载荷相对于通用锁钉分别提高了14.71%,14.51%,23.84%。有限元分析结果显示,在不同工况下使用“棒槌形”锁钉与使用通用锁钉固定的胫骨骨折模型和带锁髓内钉模型的最大Von Mises应力值和最大位移基本一致,应力分布情况基本相似;而不同位置“棒槌形”锁钉的最大Von Mises应力值和最大位移均明显低于通用锁钉的,且应力向锁钉两端分散。结论:“棒槌形”锁钉比通用锁钉的抗弯曲强度高,其应力向锁钉两端分散,不易发生疲劳断裂,故其力学性能优于通用锁钉。
[Abstract]:Tibial fracture is a common long-tube fracture, intramedullary nail fixation is one of the main methods of its surgical treatment. At present, most of the interlocking intramedullary nails used in clinic are static fixation, which has high stress blocking effect and fatigue fracture of locking nail, which will affect the healing of fracture and increase the pain of patients, and hinder the development of its clinical application. Therefore, it is an urgent problem to seek a kind of intramedullary nail and locking nail which can not only make the fracture end fixation reliable, but also eliminate the stress occlusion effect. In order to reduce the risk of nail breakage in clinic and realize the automatic transformation of intramedullary nail static and dynamic to eliminate the high stress occlusion effect, the research group designed a "stick mallet" high thread locking nail with interlocking nail, which is expected to effectively reduce the risk of nail breakage in clinical practice. To create a better mechanical environment for fracture healing. However, the mechanical properties of the high thread locking nail need a series of analysis and research. Objective: to study the mechanical properties of "bar-mallet" high thread locking nail, to verify its mechanical advantages, and to provide theoretical and scientific basis for its clinical application. Methods: according to the measurement data of Chinese tibial medullary cavity, the patients were divided into three groups according to the span of 30mm to 40mm and 50mm. According to the actual force of locking nail during fracture fixation, the corresponding experimental fixture was designed. The test locking nail was manufactured according to the span. The bending strength of the nail was measured by three point bending mechanics test and compared with that of the common locking nail. Based on the two-dimensional fault data of tibia obtained by CT scanning, a three-dimensional solid model of tibia was constructed by using Mimics,Geomagic Studio and other software. Intramedullary nail, "bar mallet" locking nail and common nail model were established with Pro/E software and assembled with tibial three-dimensional solid model. Two kinds of interlocking intramedullary nails were introduced into ANSYS software to fix tibial fracture, and the standing of tibial fractures was simulated by using two kinds of interlocking intramedullary nails. The finite element analysis of tibia force was carried out under the condition of standing on one foot, walking slowly and torsion. Results: the results of mechanical tests showed that the average maximum bending load of the "bar" locking nail was higher than that of the common locking nail in the three groups with different span in the elastic strain range, among which the average maximum bending load of the "bar" locking nail was higher than that of the common locking nail. The average maximum bending load of group C "bar hammer" locking nail is 14.71% and 14.51% higher than that of common nail, respectively. The results of finite element analysis show that the maximum Von Mises stress and maximum displacement of tibial fracture model and interlocking intramedullary nail model are basically the same as those of tibial fracture model and interlocking intramedullary nail model. The stress distribution is basically similar; However, the maximum Von Mises stress and the maximum displacement of the "bar mallet" locking nail in different positions are obviously lower than those of the common locking nail, and the stress is dispersed to the two ends of the lock nail. Conclusion: the bending strength of "bar hammer" locking nail is higher than that of common lock nail, and the stress is dispersed to both ends of lock nail, and fatigue fracture is not easy to occur, so its mechanical property is superior to that of common lock nail.
【学位授予单位】：天津理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：R687.3

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