Tribocorrosion in Modular Hip Joint Junctions-A Parametric Mechanistic Study

关节炎影响5000万美国成年人（其中大多数年龄<65岁），每年花费1280亿美元，并且仍然是美国残疾的最常见原因。到2030年，估计有6700万成年人（四分之一） 预计会受到关节炎的影响。在严重的情况下，全髋关节置换术（THR）被认为是一种具有成本效益和临床成功的干预措施。功能良好的THR应该是持久的（持续患者的生命周期），并使患者能够继续正常生活，对宿主身体的副作用最小。目前，THR的平均寿命估计为15年，最有可能随后进行多次翻修手术，特别是在年轻患者的情况下。金属基髋关节植入物的主要问题之一是股骨柄在组配式连接处的松动和随后的失效。由于机械微动（微动磨损）的耦合作用和两种金属在腐蚀环境中的接触，模块化连接受到严重关注，腐蚀环境主要由于电偶耦合导致腐蚀动力学变化。对取出的金属植入物进行的大量表面分析报告证明了组配式连接处的微动腐蚀证据。先前关于组配式连接件微动腐蚀的研究报告了机械辅助腐蚀（MAC）的有害作用，这是与机械磨损相关的腐蚀速率不可预测的加速。因此，需要将摩擦学和腐蚀联系起来的摩擦腐蚀协同方法来识别模块化连接处的失效途径。在这项研究中，影响钛和钴铬钼合金在模拟连接环境中的摩擦腐蚀行为的基本机制将进行。该技术将解决机械作用、电化学降解、金属离子和组配式连接界面处存在的磨损碎屑之间的相互作用。本申请的目的是明确定义潜在的机制， 髋关节假体在组配式连接处的早期失效。我们提出以下具体目标。目的1：确定潜在的微动制度和pH值和负载对腐蚀趋势的影响。目标二：研究金属界面的电化学特性和腐蚀动力学的可变性作为pH值和负载的函数目的3：开发钛和钴铬钼合金的摩擦腐蚀协同模型，并确定作为pH值和微动制度的函数的机械转变。预计在项目完成后，将确定与摩擦腐蚀相关的失效机制，并提出设计改进建议，以提供更安全的模块化连接，这将有助于NIAMS为关节炎关键阶段的患者提供长期解决方案的使命。PHS 398/2590（修订版06/09）页续格式页

DESCRIPTION (provided by applicant): Arthritis affects 50 million U.S. adults (most of whom are aged <65 years) with costs of $128 billion annually, and continues to be the most common cause of disability in the United States. By 2030, an estimated 67 million adults (one in four) are expected to be affected by arthritis. In severe cases, total hip replacements (THR) are accepted as a cost-effective and clinically successful intervention. A well functioning THR should be one that is durable (lasting for the duration of the patient's life) and enables the suffering patient o continue a normal life with minimum side effects on the host body. Currently, the average life span of a THR is estimated at 15 years most likely followed by multiple revision surgeries, particularly in the case of younger patients. One of the major concerns for metal-based hip implants is the loosening and subsequent failure of the femoral stem at the modular junction. The modular junction has been of serious concerns because of the coupled action of mechanical micro-motions (fretting) and the contact of two metals while in a corrosive environment that causes variations in the corrosion kinetics mainly due to galvanic coupling. Numerous surface analysis reports of retrieved metal implants have demonstrated evidence of fretting-corrosion at modular junctions. Previous studies on the fretting-corrosion of modular junctions reported the detrimental role of mechanically assisted corrosion (MAC) which is an unpredictable acceleration in the corrosion rates in association with mechanical wear. Hence, the synergistic approach of tribocorrosion that links tribology and corrosion is necessary to identify the pathways of failure at modular junctions. In this investigation the fundamental mechanisms influencing the tribocorrosion behavior of Ti and CoCrMo alloy in a simulated joint environment will be conducted. This technique will address the interaction between mechanical action, electrochemical degradation, metal ions and wear debris present at the modular junction interface. The objective in this application is to clearly define the potential mechanisms enabling the early failure of hip prostheses at the modular junction. We propose the following specific aims. Aim 1: Identify potential fretting regimes and the influence of pH level and load on the corrosion tendency. Aim 2: Study the electrochemical characteristics of the metal interface and the variability of the corrosion kinetics as a function of pH and load Aim 3: Develop a tribocorrosion synergistic model for Ti and CoCrMo alloys and identify the mechanistic transitions as a function of pH and fretting regime. It is expected that after the completion of ths project the failure mechanisms related to tribocorrosion will be determined and design improvements can be proposed to provide a safer modular junction that will assist the NIAMS mission of long-term solutions for the patients at a critical stage of arthritis. PHS 398/2590 (Rev 06/09) Page Continuation Format Page