Preventing Total Hip Modular Junction Fretting through Optimal Surface Topography

 描述（由申请人提供）：在了解组配式锥形连接在体内的表现方面存在根本性差距，最近全髋关节置换术（THA）中组配式锥形连接问题的重现表明了这一点。具体而言，耳轴和股骨头锥形表面的形貌（以周向机加工痕迹的形式）被怀疑起了作用。这一差距的持续存在是一个重要的问题，因为直到它被填补，知识如何改善模块化连接仍然在很大程度上是不可理解的。长期目标是确定耳轴-股骨头锥形表面形貌组合，以最大限度地减少体内微动，并在组装过程中实现最大的公差，从而降低微动磨损和腐蚀的可能性。本申请的总体目标是确定组装和循环载荷后表面形貌与植入物稳定性之间的关系，并确定现代THA的目标最佳表面形貌。中心假设是，具有较浅、间距更宽的机加工痕迹的表面形貌在组装后将具有较高的拔出载荷和关闭扭矩，在循环载荷下的微动较少，并且对取出的植入物的严重损坏较少。提出的研究的基本原理是，确定最大限度地减少微动的表面形貌将导致改进的模块化连接，减少植入失败。将根据三个特定目标对中心假设进行测试：1）表征耳轴-头锥表面地形、整体植入物尺寸和取出的THA的损坏模式; 2）通过对耳轴头锥表面地形、载荷、植入物整体几何形状和材料进行参数FEA，确定循环载荷期间对初始植入物稳定性和后期稳定性最重要的因素;和3）实验测试初始稳定性和使用FEA确定为理想的耳轴-头部锥形形貌组合在循环载荷下的稳定性。在目标1下，将使用回收分析来识别与损伤等级一致的植入物特征范围，以便使用FEA进行评价。FEA将用于实现目标2，以确定在循环载荷下导致最高拔出力和关闭力矩以及最低微动的表面形貌。将在FEA确定的最佳形貌的目标3中进行实验测试。该方法是创新的，因为新的多尺度FEA方法将全球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植入物。因此，减少组配式锥形接头微动磨损和腐蚀的新策略有望产生。所提出的研究是重要的，因为它是确定如何减少微动磨损和腐蚀的模块化锥形接头的第一步。最终，这些知识有可能促进FEA和实验设计，并有助于减少美国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.