Titanium Alloys as Biomaterials: a Review

Abstract The human body primarily comprises spontaneously organized polymers like proteins and ceramic materials such as bone minerals. Additionally, trace elements in the form of metals play pivotal roles at the molecular level. Simultaneously, metals and their alloys serve as crucial structural materials for surgical implants, particularly in orthopedics, and their application has recently expanded to other tissues like blood vessels. However, the increased usage of metal implants in medicine has brought about challenges related to their limited lifespan. Metallic biomaterials encompass a variety of alloys: stainless steels, magnesium, titanium, cobalt, nickel-titanium shape memory alloys, as well as tantalum, silver, and zirconium. This review primarily focuses on titanium-based biomaterials, emphasizing critical issues concerning their clinical application. These issues encompass bone integration in porous or structured implants, joint prostheses wear, surface modification of scaffolds and implants, the general toxicity of metal ions released during corrosion, phase composition of titanium-based alloys, and fatigue failure of structures due to repetitive mechanical stress, particularly corrosion fatigue. In conclusion, the review underscores the most significant challenges associated with titanium-based biomaterials, while also highlighting the most promising approaches and strategies to address them.