Preventing Total Hip Modular Junction Fretting through Optimal Surface Topography

 描述(申请人提供)：最近在全髋关节置换术(THA)中，模块锥形接头问题的再次出现表明，在了解模块化锥形接头在体内的表现方面存在着根本的空白。具体地说，耳轴和头部锥面的地形以圆周加工痕迹的形式被怀疑起到了作用。这一缺口的持续存在是一个重要的问题，因为在它被填补之前，关于如何改进模块连接的知识在很大程度上仍然是不可理解的。长期目标是确定耳轴-锥头表面形貌组合，以最大限度地减少体内的微小运动，并在组装过程中允许最大的容错性，从而减少微动和腐蚀的可能性。这项应用的总体目标是确定装配和循环加载后表面形貌与种植体稳定性之间的关系，并确定现代THA的最佳表面形貌。中心假设是，具有更浅、更宽间隔的加工标记的表面形貌在组装后将具有更高的拔出载荷和关闭扭矩，在循环载荷下的微动较小，并且对回收的植入物的损害较小。这项拟议研究的基本原理是，确定最大限度地减少微运动的表面形貌将导致改进的模块连接，减少种植失败。中心假设将在三个特定目标下进行验证：1)表征耳轴-头锥形表面形貌、种植体整体尺寸以及回收的THA的损伤模式；2)通过对耳轴-头锥形表面形貌、载荷、种植体全局几何形状和材料进行参数化有限元分析，确定对初始种植稳定性和后来的稳定性最重要的因素；以及3)使用有限元分析对被确定为理想的耳轴-头锥形形貌组合在循环载荷下的初始稳定性和稳定性进行实验测试。在目标1下，将使用检索分析来确定与损伤等级一致的植入物特征范围，以便用有限元分析进行评估。有限元分析将被用来实现目标2，以确定在循环载荷下产生最大拉断力和关闭力矩以及最小微动的表面形貌。实验测试将在有限元分析确定的最佳地形的目标3进行。这种方法是创新的，因为它是一种新颖的多尺度有限元分析方法，它将全局THA模型与局部表面形貌联系起来，以确定局部表面形貌如何影响整个种植体。因此，预计将产生减少模块锥形接头微动和腐蚀的新策略。这项拟议的研究意义重大，因为它是确定如何减少模块锥形连接中的微动和腐蚀的第一步。最终，这些知识有可能促进有限元分析和实验设计，并帮助减轻美国TKA翻修手术日益增长的负担。

 DESCRIPTION (provided by applicant): There is a fundamental gap in understanding how modular taper junctions behave in vivo, as indicated by the recent resurgence of problems with modular taper junctions in total hip arthroplasty (THA). Specifically, the topography of the trunnion and head taper surfaces, in the form of circumferential machining marks, is suspected to play a role. Continued existence of this gap represents an important problem because until it is filled, knowledge of how to improve modular junctions remains largely incomprehensible. The long term goal is to determine trunnion-head taper surface topography combinations that minimize micromotion in vivo and allow for the greatest forgiveness during assembly, thereby reducing the potential for fretting and corrosion. The overall objective of this application is to determine the relationship between surface topography and implant stability after assembly and cyclic loading and identify target best surface topographies for modern THAs. The central hypothesis is that surface topographies with shallower, more widely spaced machining marks will have higher pull-off loads and turn-off torques after assembly, less micromotion under cyclical loading, and less severe damage on retrieved implants. The rationale underlying the proposed research is that, determining the surface topography that minimizes micromotion will result in improved modular junctions, reducing implant failure. The central hypothesis will be tested under three specific aims: 1) Characterize trunnion- head taper surface topographies, global implant dimensions, and damage patterns of retrieved THAs; 2) Determine the factor most important for initial implant stability and later stability during cyclic loading by performin a parametric FEA of trunnion-head taper surface topography, load, implant global geometry, and material; and 3) Experimentally test both initial stability and stability under cyclic loading of trunnion-head taper topography combinations identified as ideal using FEA. Under aim 1, retrieval analysis will be used to identify ranges of implant characteristics consistent with grade of damage for evaluation with FEA. FEA will be used to achieve aim 2 to determine the surface topography that results in highest pull-off force and turn-off moment and lowest micromotion under cyclical loading. Experimental testing will be performed in aim 3 of the FEA identified best topographies. The approach is innovative because of the novel multi-scale FEA approach which links a global THA model to the local surface topography to determine how the local surface topography affects the entire implant. As a consequence, new strategies for reducing fretting and corrosion of modular taper junctions are expected to result. The proposed research is significant because it is the first step towards determining how to decrease fretting and corrosion in modular taper junctions. Ultimately, such knowledge has the potential to advance both FEA and experimental design and help reduce the growing burden of TKA revision surgery in the United States.