Calculation of Total Joint Replacement Contact Forces During Level Walking

描述（由申请人提供）：全关节置换术（TJR）可以减轻关节疾病患者的疼痛并增加功能活动能力。由于原发性TJR植入的患者年龄更小、体重更重、更活跃，预计TJR翻修率会增加。聚乙烯磨损已被确定为TJR失效的主要原因；因此，临床前磨损分析在设计过程中起着至关重要的作用。临床前分析TJRs需要准确的关节接触力数据，而这些数据很难获得。一个令人困惑的问题是患者步态和活动的变化会导致不同的接触力和相应的聚乙烯磨损。TJR磨损模拟器很可能不能代表所有TJR患者，但建议使用多组输入数据用于磨损模拟器以解释这种差异是不现实的。一个经过验证的数学模型可以计算接触力并允许输入数据的变化，可以为临床前测试增加有价值的见解。我们建议扩展我们之前的建模方法，以准确计算TJR患者的接触力。我们的方法允许肌肉激活水平的变化，以解释生理肌肉活动的全部范围，并导致接触力的解决空间，而不是一个剖面。所提出的研究将产生一个能够提供准确的接触力的模型，并且足够灵敏地识别各种负载条件下TJR接触力的差异。长期目标是提供额外的信息，以帮助关节置换的设计，这将有助于提高种植体的寿命。我们的总体假设是，与器械关节置换术的体内力相比，一个新的联合下肢参数化模型将比孤立的髋关节和膝关节模型更有效地约束解空间。我们提出三个目标来调查我们的总体假设。在第一个目标中，我们将验证我们的数学模型。第二个目的是比较两种模型计算的接触力的解空间。在第三个目标中，我们将通过比较两个全膝关节置换术患者队列的新模型计算的接触力来研究相关的临床应用。与公共卫生相关：我们建议开发一个新的下肢数学模型来计算关节置换术患者的关节接触力。该模型将能够为可变的患者步态和活动提供关节接触力，否则无法获得。由于需要翻修手术的全关节失败率不断增加，我们的长期目标是通过提供接触力来补充全关节模拟器提供的信息，从而帮助提高种植体的使用寿命。

DESCRIPTION (provided by applicant): Total joint replacement (TJR) surgery decreases pain and increases functional mobility for patients with joint disease. As primary TJRs are implanted in patients who are younger, heavier, and more active, increases in TJR revision rates are expected. Polyethylene wear has been identified as a leading cause of TJR failure; therefore preclinical wear analysis has an essential role in the design process. Preclinical analysis of TJRs requires accurate joint contact force data which are difficult to obtain. A confounding issue is that variation in patient gait and activities results in different contact forces and corresponding polyethylene wear. It is likely that TJR wear simulators do not represent all TJR patients, but it is unrealistic to suggest that more than one set of input data be used for wear simulators to account for such variation. A validated mathematical model which calculates contact forces and allows variation of input data could add valuable insight for preclinical testing. We propose to extend our previous modeling methods to accurately calculate contact forces for TJR patients. Our methodology allows for variation in muscle activation levels to account for the full range of physiologic muscle activity and results in a solution space of contact forces rather than one profile. The proposed research will result in a model that can provide accurate contact forces and be sensitive enough to discern differences in TJR contact forces under a variety of loading conditions. The long-term objective is to provide additional information to aid the design of joint replacements which will help improve implant longevity. Our overall hypothesis is that a novel parametric model of the combined lower limb will constrain the solution space more effectively than isolated hip and knee models when compared to in vivo forces from instrumented joint replacements. We propose three aims to investigate our overall hypothesis. In the first aim we will validate our mathematical model. With the second aim we will compare the solution space of contact forces calculated with both models. In aim three we will investigate a relevant clinical application by comparing contact forces calculated with the new model for two total knee replacement patient cohorts. Relevance to Public Health: We propose to develop a new mathematical model of the lower limb to calculate joint contact forces for joint replacement patients. The model will be able to provide joint contact forces for variable patient gait and activities which are not otherwise available. Because of the increasing rate of total joint failures requiring revision surgery, our long-term aim is to help improve implant longevity by providing contact forces to supplement information provided by total joint simulators.