Abstract
Mg-based alloys have great potential for development into fixation implants because of their highly biocompatible and biodegradable metallic properties. In this study, we sought to determine the biocompatibility of Mg60Zn35Ca5 bulk metallic glass composite (BMGC) with fabricated implants in a rabbit tendon–bone interference fixation model. We investigated the cellular cytotoxicity of Mg60Zn35Ca5 BMGC toward rabbit osteoblasts and compared it with conventional titanium alloy (Ti6Al4V) and polylactic acid (PLA). The results show that Mg60Zn35Ca5 BMGC may be classed as slightly toxic on the basis of the standard ISO 10993-5. We further characterized the osteogenic effect of the Mg60Zn35Ca5 BMGC extraction medium on rabbit osteoblasts by quantifying extracellular calcium and mineral deposition, as well as cellular alkaline phosphatase activity. The results of these tests were found to be promising. The chemotactic effect of the Mg60Zn35Ca5 BMGC extraction medium on rabbit osteoblasts was demonstrated through a transwell migration assay. For the in vivo section of this study, a rabbit tendon–bone interference fixation model was established to determine the biocompatibility and osteogenic potential of Mg60Zn35Ca5 BMGC in a created bony tunnel for a period of up to 24 weeks. The results show that Mg60Zn35Ca5 BMGC induced considerable new bone formation at the implant site in comparison with conventional titanium alloy after 24 weeks of implantation. In conclusion, this study revealed that Mg60Zn35Ca5 BMGC demonstrated adequate biocompatibility and exhibited significant osteogenic potential both in vitro and in vivo. These advantages may be clinically beneficial to the development of Mg60Zn35Ca5 BMGC implants for future applications.
Highlights
Magnesium (Mg) alloys have emerged as ideal candidates for the surgical fixation of implants because of their highly biocompatible and biodegradable metallic properties
The intergroup comparison of the bone mineral density (BMD) surrounding the implant sites showed that the Mg60Zn35Ca5 bulk metallic glass composite (BMGC) and Ti6Al4V alloy groups achieved significantly levels of BMD (p < 0.001) higher than those of the control and polylactic acid (PLA) groups, at both 12 and 24 weeks of implantation (Figure 7B)
We found that the BMD of the Ti6Al4V alloy group for the metallic implant groups decreased from week 12 to week 24, but this phenomenon was not observable in the Mg60Zn35Ca5 BMGC group
Summary
Magnesium (Mg) alloys have emerged as ideal candidates for the surgical fixation of implants because of their highly biocompatible and biodegradable metallic properties. Compared with other conventional materials used for surgical fixation, such as stainless steel or titanium alloy (Ti6Al4V), Mg-based alloys have Young’s moduli similar to bone, lowering the risk of the load-shielding phenomenon after in vivo implantation [1]. Biodegradability is another major advantage of Mg-based alloys, as there is no need for a second operation to remove the implant after bony union is achieved. Mg60Zn35Ca5 bulk metallic glass composite (BMGC) has been reported to exhibit a degradation rate much lower than those of traditional Mg-based crystalline alloys because of its single-phase structure [4]. The dispersion of titanium particles within the composite markedly improve the compressive strength and brittleness of Mg60Zn35Ca5 BMGC relative to those of conventional biodegradable implants made of synthetic polymers, rendering it a suitable candidate for developing load-bearing bone fixation devices [5]
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