Assessment of Cellular Reactions to Magnesium as Implant Material in Comparison to Titanium and to Glyconate Using the Mouse Tail Model

Abstract

Purpose Nowadays, research in magnesium alloys as a biodegradable implant material has increased. The aim of this study was to examine osteoinductive properties and tissue responses to pure magnesium in comparison to conventional permanent (titanium) and to degradable (glyconate) implant materials. Methods Magnesium wires (0.4 mm in diameter, 10 mm length) were implanted into tail veins of mice and examined after 2, 4, 8, 16 and 32 weeks. Titanium and glyconate as controls were assessed after 2, 4, 8 and 24 weeks. μ-computed tompgraphy, histology and SEM examinations were performed. Results Magnesium implants showed increasing structural losses over time with fragmentation after an observation period of 32 weeks. Glyconate was fully degraded and titanium remained almost unaffected after 24 weeks. In contrast to some titanium and glyconate implants, first calcium and phosphate precipitations could be observed around magnesium implants after two weeks. However, ossification could not be observed even after 32 weeks, whereas enchondral ossification was found partially in the sourrounding of glyconate and titanium implants after eight weeks. Nevertheless, magnesium implants showed less inflammatory responses and fibrosing properties than the conventional implant materials. Conclusions Although the assumed osteoinductive properties could not be detected, magnesium appears to be a promising degradable implant material because of the low sensitizing and inflammatory potential.

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

“…While very fast degrading alloys induce severe local effects in bony environments, including local inflammation, bone resorption, and excessive periosteal reactions, slow degrading alloys are tolerated well in general . Pure magnesium and a variety of different alloys have already been tested in vivo . Major alloy components are calcium, aluminum, zinc, lithium, and rare earth elements or zirconium, which are alloyed in amounts up to approximately 10%.…”

“…When planning an animal study, the research question should be clearly defined. If, in a first step, the general biocompatibility concerning local effects on soft tissue, as well as systemic responses, is the focus of interest, subcutaneous, 34,43 inter/intramuscular, 34,43 or intravascular implantation 50,60 in mice or rats can give a first indication of whether a biomaterial is promising for further applications. For orthotopic implant locations, the rat is superior, due to its size and consequent applicability of implant material in bony structures.…”

Susceptibility of metallic magnesium implants to bacterial biofilm infections

“…When the production exceeds the diffusion rate hydrogen gas can accumulate in tissue cavities while soluble ions together with other molecules from the physiological environment can form precipitates that result in a protective, biocompatible corrosion layer on implant surfaces . The corrosion rate and associated side effects can be further reduced by measures such as the choice of appropriate alloy compositions, manufacturing procedures or by coatings . Together with advantageous mechanical properties these efforts have resulted in substantial progress to the point where first clinical applications could be reported .…”

“…[8][9][10][11] The corrosion rate and associated side effects can be further reduced by measures such as the choice of appropriate alloy compositions, manufacturing procedures or by coatings. [12][13][14][15][16][17][18][19] Together with advantageous mechanical properties these efforts have resulted in substantial progress to the point where first clinical applications could be reported. [20][21][22][23] Implant surfaces are prone to microbial colonization.…”

Differential magnesium implant corrosion coat formation and contribution to bone bonding

“…In vitro corrosion in technical salt water corrosion solutions proceeded more rapidly than in vivo, which has been attributed to elevated concentrations of chloride ions and the solubility of magnesium chloride. In a biological environment, the incorporation of protective carbonates, calcium phosphates and proteins reinforces the magnesium corrosion layer which is thought to improve the biocompatibility of magnesiumbased implants and to reduce side effects [7][8][9][10] . Calcium phosphate coatings are highly biocompatible and have also been proposed to promote new bone formation which would be beneficial for both, implant fixation and the healing of damaged bones 11 .…”