Biodegradable magnesium alloys as promising materials for medical applications (Review)

Non-degradable steel and titanium implants used to replace defects of the locomotor system or fabricate vascular stents provide maximum stability but have too many drawbacks. Currently, biodegradable magnesium alloys are considered as promising materials for creation of fixation devices in orthopedics and cardiovascular surgery. First attempts of using magnesium-based implants for bone fixation were made as early as at the beginning of the 20th century, however, due to a high corrosion rate and gas formation they turned out to be unsuccessful. Magnesium-based alloys developed recently demonstrate improved anti-corrosion and mechanical properties and are promising for manufacturing of biodegradable, biocompatible metal implants. The microstructure of magnesium implants, their mechanical properties, electrochemical behavior, and kinetics of degradation are affected by alloying elements, methods of surface coating, and thermomechanical treatment of implants. All these factors determine the rate of alloy degradation in physiological environment and the level of gas formation. Although preclinical studies and even singular pilot clinical trials of the medical devices based on magnesium alloys have been carried out recently, there remain many unsolved issues preventing the introduction of biodegradable magnesium alloys in clinical practice. This review discusses the most promising directions in the development of biomedical materials based on magnesium alloys, existing limitations, and challenges of their use. The possibility of employing biodegradable magnesium alloys in oncology is also shown.