Bio-tribo-corrosion resistant 3D Printed Composites for Load-bearing Implants

在承重植入物中，全髋关节置换术（THA）可能是临床上最常见的 成功的干预。CoCrMo合金是一种耐磨材料，通常用于 全髋关节置换术的股骨头。THA的体内寿命通常由于碎片的产生而缩短，并且Co 和Cr金属离子从模块化接合处释放。耳轴锥度腐蚀的处理 目前，CoCrMo股骨头和Ti6 Al 4V股骨柄的使用仍然是一个严峻的挑战。锥体腐蚀 发生的主要原因是机械辅助缝隙腐蚀（MACC）沿着微动磨损 和电化学腐蚀，并导致不良局部组织反应（ALTR），免疫- 介导的生物反应，由于钴和铬离子升高。ALTR对 骨，导致植入物失效，这可能导致早期翻修手术。Co和Cr离子可以 也会引起其他症状，如耳聋、失明和间质细胞损伤， 肾功能受损我们的应用集中在自润滑和自修复 磷酸钙（CaP）增强钛或钴铬钼合金，以最大限度地减少生物摩擦腐蚀， 例如THA中模块化锥形互锁中的耳轴。CoCrMo-CaP复合材料将 与纯CoCrMo合金相比，设计旨在最大限度地减少Co和Cr离子释放;而Ti合金- CaP复合材料将被设计为完全消除由于以下原因而释放的Co和Cr离子： 腐蚀或磨损降解。 这项研究的目的是验证我们的中心假设，即基于CaP的固体 Ti或CoCrMo合金中的润滑剂将在接触表面形成原位膜，以最大限度地减少生物接触。 减少金属离子的释放。基本原理是，一旦我们理解了 摩擦膜的形成机制及其对生物摩擦腐蚀的影响，我们可以设计 具有降低的体内金属离子释放可能性的植入物。我们的初步数据显示 CaP增强Ti6 Al 4V或CoCrMo合金在体外生物摩擦过程中的摩擦膜形成 腐蚀研究摩擦膜的存在降低了磨损引起的损伤并使金属离子最小化 体外释放。我们有三个具体目标的拟议方案-（1）了解 CaP增强钛合金基复合材料的摩擦腐蚀机理和摩擦膜的形成， 并测量其体外生物学反应;（2）了解摩擦腐蚀机理， CaP增强CoCrMo复合材料的摩擦膜形成，并测定其体外生物活性 反应，和（3）测量添加CaP的Ti或CoCrMo合金的体内生物学性质。

Among load-bearing implants, total hip arthroplasty (THA) is probably the most clinically successful intervention. CoCrMo alloy, a wear resistant material of choice, is typically used in femoral heads for THAs. In vivo life of THAs are often reduced due to debris generation, and Co and Cr metal ion release from modular junctions. Management of taper corrosion from trunnions of CoCrMo head and Ti6Al4V stems remain a serious challenge today. Taper corrosion happens primarily due to mechanically assisted crevice corrosion (MACC) along with fretting and galvanic corrosion, and leads to adverse local tissue reactions (ALTR), an immune- mediated biological reaction due to elevated Co and Cr ions. ALTR has profound influence on bone, leading to implant failure, which can result in early revision surgery. Co and Cr ions can also cause other symptoms such as deafness, blindness, and interstitial cell damage resulting in impaired renal functioning. Our application is focused on self-lubricating and self-healing calcium phosphate (CaP) reinforced Ti- or CoCrMo-alloys to minimize bio-tribocorrosion in applications such as trunnions in modular taper interlocks in THAs. CoCrMo-CaP composite will be designed to minimize Co and Cr ion release compared to pure CoCrMo alloy; while Ti alloy- CaP composites will be designed to completely eliminate the release of Co and Cr ions due to corrosion or wear degradation. The objective of this proposed research is to test our central hypothesis that CaP based solid lubricants in Ti or CoCrMo alloys will form an in situ film at the contact surface to minimize bio- tribo-corrosion and reduce metal ion release. The rationale is that once we understand the mechanisms of tribofilm formation and its influence on bio-tribo-corrosion, we can design implants with reduced metal ion release possibility in vivo. Our preliminary data show in situ tribofilm formation with CaP reinforcement in Ti6Al4V or CoCrMo alloys during in vitro bio-tribo- corrosion studies. Presence of tribofilm lowered wear induced damage and minimized metal ion release in vitro. We have three Specific Aims for the proposed program – (1) to understand tribocorrosion mechanism and tribofilm formation in CaP reinforced Ti-alloy matrix composites, and measure their in vitro biological response; (2) to understand tribocorrosion mechanism and tribofilm formation in CaP reinforced CoCrMo composites, and measure their in vitro biological response, and (3) to measure in vivo biological properties of CaP added Ti or CoCrMo alloys.