University of Leeds, School of Mechanical Engineering, Institute of Functional Surfaces, Leeds, UK.
University of Leeds, School of Mechanical Engineering, Institute of Functional Surfaces, Leeds, UK.
Med Eng Phys. 2020 Sep;83:34-47. doi: 10.1016/j.medengphy.2020.07.017. Epub 2020 Jul 22.
Taper degradation in Total Hip Replacements (THR) has been identified as a clinical concern, and the degradation occurring at these interfaces has received increased interest in recent years. Wear and corrosion products produced at the taper junction are associated with adverse local tissue responses, leading to early failure and revision surgery. Retrieval and in-vitro studies have found that variations in taper design affect degradation. However, there is a lack of consistent understanding within the literature of what makes a good taper interface. Previous studies assessed different design variations using their global parameters assuming a perfect cone such as: taper length, cone angle and diameters. This study assessed geometrical variations of as-manufactured head and stem tapers and any local deviations from their geometry. The purpose of this study was to provide a greater insight into possible engagement, a key performance influencing parameter predicted by Morse taper connection theory. This was achieved by taking measurements of twelve different commercially available male tapers and six female tapers using a coordinate measurement machine (CMM). The results suggested that engagement is specific to a particular head-stem couple. This is subject to both their micro-scale deviations, superimposed on their macro-scale differences. Differences in cone angles between female and male tapers from the same manufacturer was found to create a predominately proximal contact. However, distally mismatched couples are present in some metal-on-metal head-stem couples. On a local scale, different deviation patterns were observed from the geometry which appeared to be linked to the manufacturing process. Future work will look at using this measurement methodology to fully characterise an optimal modular taper junction for a THR prosthesis.
在全髋关节置换术（THR）中，已经确定了锥度降解是一个临床关注的问题，近年来，这些界面处的降解受到了越来越多的关注。在锥度连接处产生的磨损和腐蚀产物与不良的局部组织反应有关，导致早期失效和翻修手术。检索和体外研究发现，锥度设计的变化会影响降解。然而，文献中缺乏对什么是良好的锥度界面的一致理解。以前的研究使用其全局参数评估了不同的设计变化，假设一个完美的圆锥体，如：锥度长度、锥角和直径。本研究评估了制造的头和柄锥的几何变化以及它们几何形状的任何局部偏差。本研究的目的是提供更多关于可能的配合的深入了解，这是 Morse 锥连接理论预测的一个关键性能影响参数。这是通过使用坐标测量机（CMM）对 12 种不同的商用男性锥和 6 种女性锥进行测量来实现的。结果表明，配合是特定于特定的头柄对的。这取决于它们的微观尺度偏差，叠加在它们的宏观尺度差异上。同一制造商的女性和男性锥之间的锥角差异导致主要是近端接触。然而，在一些金属对金属的头柄对中存在远端不匹配的对。在局部尺度上，从几何形状观察到不同的偏差模式，这似乎与制造过程有关。未来的工作将研究使用这种测量方法来充分描述 THR 假体的最佳模块化锥度连接。
