Magnesium alloys: A stony pathway from intensive research to clinical reality. Different test methods and approval‐related considerations

Abstract

The first degradable implant made of a magnesium alloy, a compression screw, was launched to the clinical market in March 2013. Many different complex considerations are required for the marketing authorization of degradable implant materials. This review gives an overview of existing and proposed standards for implant testing for marketing approval. Furthermore, different common in vitro and in vivo testing methods are discussed. In some cases, animal tests are inevitable to investigate the biological safety of a novel medical material. The choice of an appropriate animal model is as important as subsequent histological examination. Furthermore, this review focuses on the results of various mechanical tests to investigate the stability of implants for temporary use. All the above aspects are examined in the context of development and testing of magnesium-based biomaterials and their progress them from bench to bedside. A brief history of the first market launch of a magnesium-based degradable implant is given. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 329-347, 2017.

The Reduction of Dissolved Oxygen During Magnesium Corrosion

“…This is because corrosion can either be one of the main drawbacks of magnesium structures (for example in the automotive industry) or its core working principle, which is the case for biodegradable magnesium implants . Thus, before magnesium can find its way into a wider span of applications and be established as a key structural material, a unified corrosion theory and reproducibility of measurements among research groups is essential . Some examples of this lack of consistency include the clarification of enhanced hydrogen evolution during anodic polarization and the disparity observed between in vitro and in vivo measurements during the biological‐induced degradation of Mg alloys .…”

“…[1] Thus, before magnesium can find its way into aw ider span of applicationsa nd be established as ak ey structural material, au nified corrosiont heory and reproducibility of measurements among research groups is essential. [2,3] Some examples of this lack of consistency include the clarification of en-hanced hydrogen evolution duringa nodic polarization and the disparity observed between in vitro and in vivo measurements during the biological-induced degradation of Mg alloys. [2,[4][5][6] Contraryt om ost corrosion scenarios observed in other metals, duringt he corrosion of magnesium, dissolved oxygen (DO) is widelyd isregarded as an important cathodicr eagent.…”

Development of magnesium implants by application of conjoint‐based quality function deployment

“…Excess magnesium is excreted in the blood and, finally, in the urine (Mantripragada et al, 2013;Walker et al, 2014). The complete degradation makes additional removal surgery unnecessary, and eliminates corresponding health risks such as neurovascular injuries, damage to surrounding tissue, wound healing disorders, refractures, or unexpected complications during the removal of the hardware due to, for example, ruined screw heads (Husain, Pollak, Moehring, Olson, & Chapman, 1996;Krettek & Mommsen, 2012;Seitz, Lucas, & Kirschner, 2016;Willbold et al, 2017;Wu & Shih, 1995). In addition, magnesium implants promote the healing process due to their mechanical properties, which are close to those of bones (Li et al, 2016).…”

“…Notwithstanding the advantages of magnesium alloys, researchers have also revealed some problematic issues and drawbacks that are hampering the further penetration of competitive degradable magnesium implants into the market. In particular, the challenges include the control of degradation (Agarwal, Curtin, Duffy, & Jaiswal, 2016;Castro & Durán, 2018;Pogorielov, Husak, Solodivnik, & Zhdanov, 2017;Rahim, Ullah, & Mueller, 2018;Sanchez, Luthringer, Feyerabend, & Willumeit, 2015;Sezer, Evis, Kayhan, Tahmasebifar, & Koç, 2018;Song, 2007a;Zheng, Gu, & Witte, 2014) and mechanical integrity, the production of hydrogen gas during degradation (Witte et al, 2008), the strength (Pogorielov et al, 2017;Rahim et al, 2018;Willbold et al, 2017), and modifications of the surface to reduce biofilm-related infections (James, 2016;Rahim et al, 2018), which are essential requirements for long-term patient care and optimal healing processes.…”

Döküm Ve Haddelenmi̇ş Az31b Magnezyum Alaşiminin Kuru Şartlarda Aşinma Davranişinin Kiyaslanmasi

“…Magnesium alloys have also been widely studied as potential materials for temporary medical implants owing to its strength and safe absorbability by the human body, and they have been progressed to some preclinical studies and product commercialization [3,4]. Among them, Mg-Al are the most common magnesium alloys having superior castability, good corrosion resistance, reasonable mechanical properties and acceptable processing cost [5,6].…”