Rheological Modelling of Knee Joints

退化作用，无论是由于自然老化，疾病或损伤，是一种常见的发生在人类关节的寿命。美国每年进行200，000例矫正手术，英国每年进行80，000例矫正手术，预计到2020年将增长170%。然而，植入物并非没有并发症;当前设计中存在许多不合格的领域。例如，植入物的当前使用寿命约为15年，这对于计划寿命超过15年的患者来说是不方便的。此外，金属植入物的磨损会导致金属离子释放，这在生物学背景下最好避免，以及导致松动和失效。虽然有许多关于种植体磨损的实验研究，但数值建模是相对较少探索的，尽管对种植体设计同样重要。这两项都是植入物设计确认所必需的。数值模型将允许资源有效的优化设计的植入物适合不同的使用要求。人类关节非常类似于弹性流体动力润滑，与滑液作为润滑剂。虽然大多数以前的研究认为它是一种日常使用的牛顿流体，但有实验证据表明并非如此，这为研究这一问题提供了动力。如果可以通过回归分析或其他方式开发滑液的流变学模型，则可以将其实施到已经存在的人类关节模型中。这对该部门目前正在进行的膝关节建模工作具有重要意义，因为它可以被潜在地纳入这些模型中，并被检查是否适合其他关节。

Degenerative action, whether due to natural aging, disease or injury, is a common occurrence during the lifetime of a human joint. 200,000 corrective procedures are performed yearly in the US and 80,000 in the UK, with an expected growth of 170% by 2020.However, implants are not without complications; there are numerous areas of incompetency in current designs. For instance, the current service life of an implant is about 15 years, which is inconvenient for patients planning to live beyond that. Furthermore, the wear from metal implants causes metal ion release which is best avoided in a biological context, as well as causing loosening and failure. While there are numerous experimental studies into wear of implants, numerical modelling is a relatively less explored albeit equally important aspect to implant design. Both are necessary for the validation of an implant design. A numerical model would allow resource efficient optimisation of the design of an implant suited for different usage requirements.Human joints closely resemble elastohydrodynamic lubrication, with synovial fluid as the lubricant. While most previous studies consider it to be a Newtonian fluid within the regimes of everyday usage, there is experimental evidence to suggest otherwise.This provides an incentive to investigate this matter. If a rheological model for synovial fluid can be developed, through regression analysis or otherwise, it can be implemented into already existing models of human joints. This is of significance to the current knee modelling effort being carried out by the department, as it can be potentially incorporated into those models as well as being examined for suitability for other joints.