Computational Methods to Predict the Robustness of Cementless Total Hip Replacements

当一个人接受髋关节置换手术时，有许多因素会影响手术持续时间，其中许多因素对患者来说并不明显。在每个患者体内，骨的性质可能会有很大差异;这种骨质量的差异在患者之间可能更加明显，特别是如果一个患者比另一个患者更活跃，更重，或者即使他们的饮食不同。其他需要考虑的因素包括骨和植入物的几何形状、周围组织的质量、与手术相关的创伤以及植入物的对齐程度，其中最后两个因素与手术技术有关。传统上，对髋关节置换术性能的实验研究仅限于每次实验分析一种情况（例如，一种对线和一种骨）。这些调查的结果实际上只能提供一个良好的定性指标，因为生物环境不能在实验室中充分模拟。除此之外，还需要大量的实验来模拟所有可能的情况（对齐、几何形状、骨质等的组合）实验研究很快变得不可行。为了解决这个缺点，已经开发出能够在短得多的时间内模拟实验测试的计算方法。然而，到目前为止，这些调查中的大多数再次描述只有一种情况，许多计算模型需要充分描述的变化，只有一个单一的参数的影响。因此，拟议的研究计划将提供新的计算工具，可以在一个单一的分析中同时有效地解释参数的变化，如骨的特性，载荷条件和手术技术。预计本研究的直接受益将包括开发能够确定当前植入物设计对错位和骨几何形状变化更宽容的模型，因此无论患者如何，都可能表现良好。在中期，这些分析应使外科医生在为患者选择最合适的植入物时做出明智的决定。从长远来看，这项研究将有助于假体制造商获得新的设计，提高性能和寿命，使制造商，健康提供者，当然还有患者受益。

When a person undergoes hip replacement surgery, there are many factors that can affect how long it will last, many of which are not immediately apparent to the patient. Within each patient, the properties of bone can vary considerably; this difference in bone quality may be even more apparent between patients, particularly if one patient is more active than another, is heavier, or even if their diets are different. Other factors to consider are the geometries of the bone and implant, the quality of the surrounding tissues, the trauma associated with surgery and how well aligned the implant is, the last two of which are related to the surgical technique. Traditionally, experimental investigations into the performance of hip replacements have been limited to analysing one situation per experiment (e.g. one alignment and one bone). The results of these investigations can really only provide a good qualitative indicator as the biological environment can not be adequately simulated in the laboratory. Add to this, the huge number of experiments that would be required to simulate all possible scenarios (combinations of alignment, geometries, bone quality etc.) and experimental investigations soon become unfeasible. In order to address this shortcoming, computational methods have been developed that are capable of simulating an experimental test in a much shorter time. However, to date, most of these investigations again describe only one situation and many computational models are required to fully describe the effect of variations in only a single parameter. The proposed research program therefore, will deliver new computational tools that can account for variations in parameters such as the properties of bone, the loading conditions and the surgical technique simultaneously and efficiently, in a single analysis. It is anticipated that the immediate benefits of this research will include the development of models capable of determining which current implant designs are more forgiving of variations in misalignment and bone geometry, and are therefore likely to perform well regardless of the patient. In the medium term, these analyses should enable the surgeon to make an informed decision when selecting the most appropriate implant for his/her patient. In the longer term, it is believed that the research will help prosthesis manufacturers to arrive at new designs with improved performance and longevity, to the benefit of the manufacturer, the health provider, and of course, the patient.