The School of Advanced Materials Engineering, Kookmin University, South Korea, and several other South Korean research centers, announce that their researchers have developed a magnesium-based orthopedic implant that safely biodegrades and promotes bone growth.
Researchers say that In the past decade, countless studies have been done to control the mechanical and corrosion properties of magnesium-based alloys, which degrade in the physiological environment. The goal was to overcome the flaws of the inert implant materials and shift the paradigm of conventional bone fixation devices.
Controlled degradation of the Mg-5Ca-1Zn alloy results in the formation of a biomimicking calcification matrix at the degrading interface to initiate the bone formation process. This process facilitates early bone healing and allows the complete replacement of the biodegradable magnesium implant by the new bone within a year of implantation, as demonstrated in 53 cases of successful long-term clinical studies.
Magnesium hydroxide is a corrosion product, and indeed, studies showed that the magnesium alloy implant progressively degraded throughout the clinical trial up to a year out, when the implant was barely distinguishable. As degradation proceeded, new bone grew in its place. The chemical composition closest to the implant-bone interface showed Mg(OH)2, which set off other reactions due to changes in pH levels. These changes lead to the formation of calcium phosphate compounds with the part of Region II closest to Region I displaying amorphous calcium compounds, and the part of Region II farther way displaying crystalline hydroxyapatite.
This crystalline product mimics the body’s natural calcification matrix, causing it to be resorbed by the osteoclasts and induce bone formation by the osteoblasts. This continuous process of magnesium alloy degradation and bone formation allows the implant to eventually disappear and new bone to appear.
Journal reference: Proceedings of the National Academy of Sciences
http://english.kookmin.ac.kr/site/academics/colleges_school/engineering.htm
