BIODEGRADABLE METAL ALLOYS FOR BIOMEDICAL IMPLANTS: A COMPREHENSIVE REVIEW

Biodegradable metals have gained substantial attention as biomaterials for medical implants due to their unique ability to gradually degrade and be absorbed by the body, eliminating the need for implant removal surgeries. Magnesium, zinc, iron, and their alloys show promise due to their biocompatibility, suitable mechanical properties, and biodegradability, making them ideal for orthopaedic and cardiovascular applications. These materials reduce long-term complications associated with permanent implants, such as stress shielding and chronic inflammation. Despite many advantages, challenges remain, including rapid or uncontrolled degradation, hydrogen gas release (notably with magnesium), loss of mechanical integrity, and potential cytotoxicity from alloying elements. To address these limitations, researchers explore alloying with biocompatible elements, surface modification techniques, and advanced fabrication methods to finely tune degradation rates and mechanical strength. Particularly, alloying magnesium with elements like calcium, zinc, and silver can enhance corrosion resistance, antibacterial properties, and mechanical performance. Manufacturing and processing techniques—including casting, thermomechanical processing, powder metallurgy, and additive manufacturing—play a critical role in defining implant microstructure, mechanical behaviour, degradation characteristics, and biological outcomes. This review summarises the current state of biodegradable metallic biomaterials, their clinical potential, limitations, fabrication advances, and emerging strategies to optimise their performance, aiming to propel safer, more effective implants for future biomedical applications.