Magnesium and its alloys as Orthopedic Biomaterials :
As a lightweight metal with mechanical properties similar to natural bone, a natural ionic presence with significant functional roles in biological systems, and in vivo degradation via corrosion in the electrolytic environment of the body, magnesium-based implants have the potential to serve as biocompatible, osteoconductive, degradable implants for load-bearing applications.
Current metallic biomaterials are essentially neutral in vivo, remaining as permanent ﬁxtures, which in the case of plates, screws and pins used to secure serious fractures, must be removed by a second surgical procedure after the tissue has healed sufﬁciently. Repeat surgery increases costs to the health care system and further morbidity to the patient. Magnesium is an exceptionally lightweight metal. With a density of 1.74 g/cm3, magnesium is 1.6 and 4.5 times less dense than aluminium and steel, respectively. The fracture toughness of magnesium is greater than ceramic biomaterials such as hydroxyapatite, while the elastic modulus and compressive yield strength of magnesium are closer to those of natural bone than is the case for other commonly used metallic implants. Moreover, magnesium is essential to human metabolism and is naturally found in bone tissue.