A Review on Surface Engineering Perspective of Metallic Implants for Orthopaedic Applications

Orthopaedic metallic implant design is expected to meet two critical challenges-biocompatibility and mechanical strength. According to a survey conducted in 2017, the global market of implants will grow by similar to 46% by 2025. Researchers have been trying to alleviate the problems of these implants, namely, biocompatibility, microbial invasion, bio-inertness, corrosion, and wear. Surface modification techniques that operate at low temperature and diffusion-based processes are preferred to circumvent the problems. These methods include thermochemical (carburizing, nitriding, etc.), electrochemical processes (electrochemical deposition, chrome plating, etc.), and ion implantation. This review presents the significance of these methods while meeting various challenges, such as wear, biocompatibility, and corrosion. The implants reviewed are stainless steel, Co-Cr alloys, titanium alloys, and magnesium alloys. Finally, the friction-stir process, another low-temperature process, has been reviewed for Mg and its alloys.