Long-term in vivo degradation behavior and near-implant distribution of resorbed elements for magnesium alloys WZ21 and ZX50

Abstract

Magnesium is generally considered to be one of the most attractive base materials for biodegradable implants, and many magnesium alloys have been optimized to adjust implant degradation. Delayed degradation, however, generates prolonged presence in the organism with the risk of foreign body reactions. While most studies so far have only ranged from several weeks up to 12months, the present study provides data for complete implant degradation and bone regeneration until 24months, for two magnesium alloys (ZX50, WZ21) with different degradation characteristics. μCT monitoring, histological staining and LA-ICP-MS illustrate the distribution of the elements in the neighboring bony tissues during implant degradation, and reveal in particular high concentrations of the rare-earth element Yttrium.

In vivo study of self‐assembled alkylsilane coated degradable magnesium devices

“…1–5 Mg is light-weight and its mechanical properties closely match those of bone. Divalent Mg 2+ ion is one of the essential ions and its corrosion products—MgO and Mg(OH) 2 are safe and can be cleared from the body.…”

In vitro and in vivo studies on as-extruded Mg- 5.25wt.%Zn-0.6wt.%Ca alloy as biodegradable metal

“…Thus the subcutaneous emphysema was observed, which might lead to the displacement of neighboring tissue and the degrading implants [15,27]. A small amount of hydrogen gas release is tolerable because the gap between tissues and implants can be refilled with cells afterwards [20]. However, excessive hydrogen evolution in vivo reduced the survival rate of rats with magnesium implants [37].…”

“…Additionally, the new bone formation is also observed in the vicinity of implants in the medullary cavity and periosteal area, which is not seen in the control group. An explanation for the new bone formation is the increased concentrations of magnesium in combination with an increase in local pH values, which would enhance the nucleation rate of apatite and improve the mineralization [20,27]. Similarly, a stimulating effect and a significant enhancement in bone formation were ARTICLES .…”

“…At week 4 postsurgery, there is no statistically significant difference (p<0.05) of serum magnesium between the magnesium group (20.4±0.4 μg mL −1 ) and control (21.7±0.7 μg mL −1 ). The stable serum magnesium level attributes to the homeostatic control of serum magnesium concentrations by kidney and/or bone, which provides a reservoir of large concentrations of magnesium to buffer acute changes in serum magnesium [20]. Moreover, the serum zinc and calcium showed no statistically significant difference (p< 0.05) between the control group (Zn 0.04 ±0.03 μg mL −1 , Ca 7.39±0.27 μg mL Table 3 compares the in vitro and in vivo corrosion rates of Mg-Zn-Ca alloys.…”

“…Yan et al [18] demonstrated that Mg-Zn alloy performed better than Ti3Al-2.5V by promoting healing and reducing inflammation. Based on the aforementioned considerations, several Mg alloys have been investigated with the addition of different contents of Ca and Zn [19][20][21][22]. All the previous studies acknowledge the biosafety of Ca and Zn addition in magnesium and support the great potential of Ca-and Zn-containing magnesium alloys for implant applications.…”