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

University Of South Florida, Tampa FL

Investigators

Abstract

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 students In 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.