In the 1st half of last century, magnesium was first introduced in the medical industry as an orthopedic biomaterial. There are many characteristics and properties that make magnesium a very attractive option for use in implants and similar applications. Other common implant materials have densities that range from 3.1-9.2g/cm3 whereas the density of natural bone is 1.8-2.1g/cm3 (112.37-131.10lb/ft3). Magnesium alloys are much more comparable at a density of 1.74-2.0g/cm3 (108.62-lb/ft3). Magnesium is also much more comparable to natural bone than other materials in regards to fracture toughness, elastic modulus and compressive yield strength. Not only does magnesium provide the mechanical and physical properties desirable in these applications, it also exhibits some special characteristics.
Magnesium is found naturally as an ion in the human body equating to about one mole in a 155lb (70kg) person, half of which is stored within bone tissue. Magnesium within the body aids in metabolic reactions, has good biocompatibility, and is nontoxic. In addition, uncoated magnesium implants can be biodegradable in bodily fluids through corrosion which eliminates the need for a second surgery to remove implants. Application of protective coatings can prevent corrosion issues for applications in which a more permanent solution is needed. Research and testing of different alloys and formulas for protective finishes is currently in progress to increase the array of ways in which magnesium can be used in medical applications.