GOALI: Tuning Degradation Properties of Metallic Implants through Polymeric Coatings and Surface Texture

在美国，每年大约有150万次关节镜手术(干涉螺钉、缝合锚)。然而，当前一代可生物降解的骨科植入物并没有完全达到预期。与常见的金属或聚合物植入物相比，镁合金将两者的优点结合到一种材料中。例如，镁螺钉可以自攻，尺寸比聚合物螺钉小，植入时对周围骨骼的伤害最小。然而，它们也是可降解的，从而开启了完全可生物再吸收金属的可能性。也就是说，镁的主要限制是它的降解速度太快，不适合大多数临床应用。这个GOALI学术联络机会(GOALI)研究项目将研究如何使用镁表面的薄阻挡涂层来延长降解时间框架，这将带来下一代完全可降解的植入物，其固定性能类似于目前可用的金属，而不需要进行后续手术。作为整体努力的一部分，还设计了一个同步和综合的教育计划，以培训学生，并使他们为应对可植入材料带来的独特挑战做好准备。与ConMed公司的合作将提供博士奖学金和工业技能之间的紧密结合，以便更彻底地为学生毕业后的工作做好准备。这项研究将广泛应用于课堂教学和初中生。在本研究项目中，将研究可生物降解聚合物涂层，以控制镁植入体的生物吸收，描述涂层工艺变量、涂层成分、机械性能和生命周期性能之间的相互关系。结果将以目前可用的生物可再吸收材料为基准。通过改变聚合物涂层的组成和相对分子质量以及通过工艺条件改变涂层的结晶度和厚度，可以假设水的可用性可以被控制，以便定制植入物的生物吸收轮廓。将讨论的研究方向包括：可降解的聚合物涂层如何控制镁表面的水有效性？2：在聚合物涂层的镁模型植入物上，早期成骨细胞附着、随后的增殖和成熟为骨形成细胞的事件是什么？3；镁表面的粗糙度如何影响镁/聚合物材料的生物降解？这些问题的答案将使人们能够预测随时间推移的退化行为，以指导未来设备的设计。

There are approximately 1.5 million arthroscopic procedures (interference screws, suture anchors) per year in the United States. However, the current generation of biodegradable orthopedic implants have not fully met expectations. Compared to commonly available metallic or polymeric implants, magnesium alloys combine the advantages of both into one material. Magnesium screws, for instance, can be made self-tapping and smaller in size than polymer screws, minimizing injury to the surrounding bone upon implantation. Yet, they are also degradable, opening up the possibility of fully bioresorbable metals. That said, the major limitation of magnesium is that its rate of degradation is too rapid for most clinical applications. This Grant Opportunity for Academic Liaison with Industry (GOALI) research project will investigate how thin barrier coatings on magnesium can be used to extend degradation time frames, which will usher in the next generation of fully degradable implants with fixation properties similar to currently available metals without the need for subsequent surgeries. As part of the overall effort, a concurrent and integrated educational program also is designed to train students and prepare them for the unique challenges presented by implantable materials. A collaboration with ConMed Corporation will offer tight integration between PhD scholarship and industrial skills in order to more thoroughly prepare students for jobs after graduation. The research will be broadly distributed into both classroom instruction and to middle and high school studentsIn this research project, biodegradable polymer coatings will be investigated to control the bioabsorption of magnesium implants delineating the interrelationships between coating process variables, coating composition, mechanical properties and life-cycle performance. Results will be benchmarked against currently available bioresorbable materials. By varying the composition and molecular weight of the polymer coating as well as changing the crystallinity and the thickness of the coating through processing conditions, it is hypothesized that water availability can be controlled in order to customize bioabsorption profiles of the implant. Lines of research that will be addressed include the following 1: How is water availability at the magnesium surface controlled by a degradable polymer coating? 2: What are the events of early pre-osteoblasts attachment followed by their subsequent proliferation and maturation into bone forming cells on polymer-coated magnesium model implants? 3; How does roughness of the magnesium surface affect the biodegradation of magnesium/polymer materials? The answers to these questions will enable predictions of degradation behavior over time to guide the design of future devices.