Wear Testing for Enhanced Prediction of TKR Clinical Performance

描述(申请人提供)：仅在美国，每年就有超过45万例手术，全膝关节置换术(TKR)已经成为一种常见的外科手术，用于减轻患病或创伤的膝关节的疼痛和增加功能活动度。TKRS使用寿命的一个主要限制因素仍然是聚乙烯胫骨衬里的磨损。预期寿命和体重的增加，以及年轻患者接受TKR手术的趋势，将对未来的设备提出更高的要求。临床前耐力测试已经成为在种植体开发过程中预测新设备机械性能的标准程序。这些测试程序遵循测试成功策略，该策略需要从日常使用的载荷和运动频谱获得输入数据。然而，最近的研究表明，目前的国际测试标准并不能模拟十字保持膝关节假体植入患者在步态过程中的运动学和运动学条件。此外，目前的协议只关注步行，完全忽略了日常生活的其他活动。虽然步行是一天中最频繁的活动，但其他日常体力活动通常比步行产生更高的胫骨负荷、更大的假肢运动和更有害的交叉剪切。事实上，测试部件的磨损特征与体内磨损的特征不匹配，无论是在磨痕的大小和形状上，还是在磨损形态上。TKRS的正面、内侧和侧面的承载表面并不是导致磨损和骨溶解的唯一表面。聚乙烯衬里背面和金属底板/托盘之间的微小运动会导致“背面磨损”。背部磨损被认为比前关节表面的磨损具有更大的溶骨意义，因为背部接触面积更大，产生的颗粒可能更小，尽管背部磨损的准确量化已被证明是困难的。日常体力活动和特定地点的TKR穿着之间的关系也是未知的。我们假设，输入到佩戴模拟器的运动和力曲线必须来自TKR患者的多个日常活动，以便准确地再现临床观察到的TKR正面和背面的磨损率和模式。我们提出三个目标来调查我们的总体假设。在前两个目标中，我们将演示使用来自TKR患者和多个日常活动的输入配置文件生成更真实的磨损。在第三个目标中，我们将设计和验证一种新的多活动磨损方案，以反映真实的体内使用情况。我们将使用新技术，使用硬脂酸镧跟踪血清中聚乙烯的磨损情况，并进行质谱分析。不同的元件用于不同的TKR界面，以实现对正面和背面磨损的原位跟踪。调查结果将通过检索独特的步态和活动信息进行验证。这些研究被故意限制在市场占有率较高的十字保留TKR设计上。 与公共健康相关：与当前的输入配置文件不同，多活动模拟器标准将产生与活体使用情况密切相关的磨损率和模式，这将提高预测磨损测试的质量。这将进一步推进和加快膝关节假体的设计进程。任何临床前消除材料和/或设计错误都会直接提高植入物的寿命，并最终影响患者的福祉。

DESCRIPTION (provided by applicant): With over 450,000 surgeries performed annually in the US alone, total knee replacement (TKR) has become a common surgical procedure to alleviate pain and increase functional mobility in diseased or traumatized knee joints. A major limiting factor to the service life of TKRs remains the wear of the polyethylene tibial liner. Increases in life expectancy and body weight, as well as the trend for TKR surgery in younger patients will put even higher demands on future devices. Preclinical endurance testing has become a standard procedure to predict the mechanical performance of new devices during implant development. These testing procedures follow a test-to-success strategy, which require input data derived from the load and motion spectrum of daily use. However, recent studies show that current international testing standards do not mimic the kinematic and kinetic conditions during gait for patients implanted with a cruciate retaining knee prosthesis. In addition, current protocols focus only on walking, completely omitting other activities of daily living. Although walking is the most frequent activity throughout the day, other daily physicals activities often generate higher tibial loads, larger prosthetic movements, and more detrimental cross-shear than walking. Indeed, wear features of tested components do not match those worn in vivo, neither regarding wear scar size and shape, nor wear morphology. The frontside medial and lateral bearing surfaces of TKRs are not the only surfaces which contribute to wear and osteolysis. Micromotion between the back of the polyethylene liner and the metallic base plate/tray leads to "backside wear". Backside wear has been claimed to be of greater osteolytic significance than the wear experienced on the front articulating surfaces because of the larger backside contact area and the potentially smaller particles generated, although accurate quantification of backside wear has proven difficult. The relationship between daily physical activity and location specific TKR wear is also not known. We hypothesize that the motion and force profiles inputted to wear simulators must be from multiple daily activities measured from TKR patients in order to accurately reproduce clinically observed wear rates and patterns on both the front and backside of TKRs. We propose three aims to investigate our overall hypothesis. In the first two aims we will demonstrate that more realistic wear is generated using input profiles from TKR patients and from multiple daily activities. In the third aim we will design and validate a new multi-activity wear protocol reflecting true in vivo use. We will use novel technology that uses lanthanide stearates to track polyethylene wear in serum with mass spectrometry. Different elements are used for different TKR interfaces to allow in situ tracking of frontside versus backside wear. Findings will be validated using retrievals with unique gait and activity information. The studies are purposefully limited to cruciate-retaining TKR design with a high market share. PUBLIC HEALTH RELEVANCE: A multi-activity simulator standard that will result in wear rates and patterns that closely reflect true in vivo use, unlike current input profiles, will improve the quality of predictive wear tests. This will further advance and speed up the design process of knee prostheses. Any preclinical elimination of material and/or design errors directly improves implant longevity and impacts ultimately the well-being of the patient.