Accelerating Corrosion of Pure Magnesium Co-implanted with Titanium in Vivo

Peng Hou,Shen Liu,Yimin Chai,Jiahua Ni,Pengfei Cheng,Shaoxiang Zhang,Xiaonong Zhang,Yuanzhuang Zhang,Hongliu Wu,Yufeng Zheng,Haidong Xu,Pei Han,Jingyi Liu,Changli Zhao

doi:10.1038/srep41924

Peng Hou, Shen Liu + Show 12 more

Open Access

https://doi.org/10.1038/srep41924

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Abstract

Magnesium is a type of reactive metal, and is susceptible to galvanic corrosion. In the present study, the impact of coexistence of Ti on the corrosion behavior of high purity Mg (HP Mg) was investigated both in vitro and in vivo. Increased corrosion rate of HP Mg was demonstrated when Mg and Ti discs were not in contact. The in vivo experiments further confirmed accelerating corrosion of HP Mg screws when they were co-implanted with Ti screws into Sprague-Dawley rats’ femur, spacing 5 and 10 mm. Micro CT scan and 3D reconstruction revealed severe corrosion morphology of HP Mg screws. The calculated volume loss was much higher for the HP Mg screw co-implanted with Ti screw as compared to that co-implanted with another Mg screw. Consequently, less new bone tissue ingrowth and lower pullout force were found in the former group. It is hypothesized that the abundant blood vessels on the periosteum act as wires to connect the Mg and Ti screws and form a galvanic-like cell, accelerating the corrosion of Mg. Therefore, a certain distance is critical to maintain the mechanical and biological property of Mg when it is co-implanted with Ti.

Highlights

Magnesium and its alloys have gained attention in recent decades as metallic biomaterials due to their excellent biocompatibility, mechanical properties and biodegradability[1,2,3]
It is well known that the corrosion behavior of Mg would be changed if it is in contact with other metal, or with the β-phase in Mg alloy[16]
It is well known that the corrosion rate and corrosion behavior of Mg are fatal to the implantation, few studies have addressed the change of the corrosion rate and corrosion behavior of Mg under conditions in which Mg and another metal were co-implanted in vivo

Summary

Introduction

Magnesium and its alloys have gained attention in recent decades as metallic biomaterials due to their excellent biocompatibility, mechanical properties and biodegradability[1,2,3]. Different metallic biomaterials might be co-implanted to maximize the therapeutic effect. Ti materials are often selected as endo-osseous implants with other alloys served as suprastructure[14]. This could occur to Mg biomaterials in orthopedic applications. In a recent clinical study, Yu et al.[15] used vascularized iliac grafting, together with commercial cannulated compression screws and magnesium screws to treat displaced femoral neck fractures in young adults. The aim of this study is to investigate the effect of titanium screws co-implantation on the corrosion behavior of pure magnesium, as well as its impact on the osteogenesis

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