Surface treatment and post-processing of metallic bio-implants: enhancing performance and biocompatibility

This review investigates the critical role of surface treatment and post-processing techniques in enhancing the performance and biocompatibility of metal bio-implants. The paper addresses the challenges posed by the significant difference in Young's modulus between natural bone (15-45 GPa) and metal alloys (110-240 GPa), which leads to stress shielding effects and potential toxic ion release. The review first details various surface coating methods, including ion implantation and anodization, highlighting their ability to improve tribological resistance, corrosion resistance, and biocompatibility. The detailed analysis gives surface modification techniques, such as laser shock peening, Nitrogen Plasma Immersion Ion Implantation (NP-III), and anodization, which are used to enhance titanium implant properties, such as increasing surface hardness, promoting tissue growth, and creating a bio-active oxide layer. Furthermore, the paper explores post-processing methods such as laser shock peening (LSP) and surface texturing, which are crucial for modifying the surface topography and microstructural properties of implants. It also discusses techniques, particularly laser-based texturing, to reduce friction and wear while inducing beneficial compressive residual stress. The review concludes by emphasizing that a tailored approach to surface modification and post-processing is essential for developing safe and effective bio-implants for a wide range of applications, from bone fixation to load-bearing joints.