On the compatibility of surgical implants of bioresorbable magnesium alloys with medical devices of titanium alloys

Abstract

Self-resorbable implants made of magnesium alloys, unlike the traditional implants made of titanium alloys and stainless steels, have the ability to completely dissolve in the human body, which makes it possible to eliminate the need for a recurrent operation to extract them. The issue of the possibility of using magnesium implants in the combination with products made of titanium alloys remains insufficiently studied at the moment. At the same time, it is widely known that the elements such as titanium and iron, with a potential more positive than magnesium, have a disastrous influence on the corrosion of magnesium alloys, since magnesium dissolves much faster due to the galvanic effect. This work is aimed to determine how the distance to a titanium implant affects the corrosion rate of a ZX10 magnesium alloy sample with an ultra-fine grain structure. As it is an issue of medical application, the authors carried out the corrosion tests within the conditions simulating the human body conditions: the corrosion medium circulation and keeping temperature within 37±1 °C. The authors used physiological solution as a corrosion medium. During corrosion testing, a titanium implant was placed in three, six, and twelve centimeters from the magnesium alloy sample; and the control tests were also carried out without a titanium implant. According to the obtained data, at a distance of 3 cm, the galvanic effect between titanium and magnesium manifests itself strongly, increasing the corrosion rate and the size of corrosion damage, but at a distance of 6 cm, the titanium implant does not have a visible effect on the corrosion of a sample.