Biodegradable magnesium alloys for short-term orthopedic implants: properties, surface modification and biological response

Abstract

Orthopedic diseases pose a significant challenge in the medical field, often requiring innovative solutions to address the unique needs of the patient. Orthopedic implants increasingly demand materials that not only meet mechanical and biological requirements, but also actively participate in the healing process. Magnesium and magnesium-based alloys are lightweight materials that have emerged as promising candidates because of their biodegradability, biocompatibility, and mechanical properties, which closely resemble natural bone. A key advantage of magnesium alloys lies in their ability to slowly degrade in vivo, which translates into their potential for use in temporary, bioabsorbable implants, thus eliminating the need for surgical removal. However, rapid and uncontrolled corrosion remains a critical barrier to their clinical translation. This review provides a focused analysis of current strategies to engineer the controlled biodegradation of magnesium-based orthopedic implants. We critically examine the role of alloying elements, surface modification techniques, and biological interactions in modulating degradation behavior. Particular attention is paid to the interaction between material design and biological response, which is essential for maintaining implant functionality during tissue regeneration. By identifying challenges and highlighting emerging directions, this review aims to support the development of next-generation biodegradable magnesium-based implants tailored for orthopedic applications. We wish to inspire more research and development into magnesium alloys biomaterials for the orthopedic field. Our manuscript entitled “Biodegradable magnesium alloys for short-term orthopedic implants: properties and surface modification methods” by Barbara Rynkus, Alessandra Scano∗, Silvia Puxeddu, Fabrizio Angius, Guido Ennas, and Janusz Szewczenko, deals with the use of magnesium based implants going beyond the poor corrosion resistance of this material - a significant challenge in the orthopedic field.Magnesium alloys, in fact, are valid materials for fabrication of temporary implants, ensuring high biocompatibility, very good mechanical properties and close resemblance to natural bone in terms of density and elastic modulus. Thus, they are excellent alternatives to currently used metal-based biomaterials. The only drawback is their poor corrosion resistance, which is directly connected to pH changes of the surrounding area, and hydrogen gas released as well, limiting their use in real applications.Within this context, we summarized in the manuscript the properties of magnesium and its alloys, the weak points related to their application, and the methods and techniques for modifying their surfaces to improve their functional properties, ensuring implant functionality in the orthopedic field.Considering that every year, the number of bone fractures resulting from accidents or illness is increasing (e. g. 178 million of new fractures only in 2019) and, as the population ages, the number of people suffering from osteoporosis grows, which also contributes greatly to the number of bone fractures that occur, we feel obliged to provide to the scientific community an overview on possible solutions to this challenge. In particular, we address researchers starting off in developing magnesium based implants, hoping to inspire more research on this side. • Biological responses of magnesium alloys induced by degradation have a decisive influence on osteogenesis and immune modulation. • Advanced surface modification strategies enable controlled biodegradation and improved biofunctionality. • Adding alloys to improve microstructure significantly enhances control of Mg degradation. • Surface treatment effectively slows corrosion and increases bioactivity. • Future progress requires the integration of material design, biological response, and degradation prediction models.

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