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Biodegradable magnesium alloys for orthopaedic applications: A review on corrosion, biocompatibility and surface modifications

Novel Magnesium Alloys Developed for Biomedical Application: A Review

https://www.tpbin.com/Uploads/Subjects/4172cde2-d3d4-4f47-8eda-5e019def129f.pdf

Magnesium alloys for temporary implants in osteosynthesis: in vivo studies of their degradation and interaction with bone.

To evaluate the ability of Mg-6Zn to replace titanium nails in the reconstruction of the intestinal tract in general surgery, we compared the Mg-6Zn and titanium implants with respect to their effects on rat's intestinal tract by biochemical, radiological, pathological and immunohistochemical methods. The results indicated that Mg-6Zn implants started to degrade at the third week and disintegrate at the fourth week. No bubbles appeared, which may be associated with intestinal absorption of the Mg-6Zn implants. Pathological analyses (containing liver, kidney and cecum tissues) and biochemical measurements, including serum magnesium, creatinine, blood urea nitrogen, glutamic-pyruvic-transaminase and glutamic-oxaloacetic-transaminase proved that degradation of Mg-6Zn did not harm the important organs, which is an improvement over titanium implants. Immunohistochemical results showed that Mg-6Zn could enhance the expression of transforming growth factor-β1. Mg-6Zn reduced the expression of tumor necrosis factor at different stages. In general, our study demonstrates that the Mg-6Zn alloy had good biocompatibility in vivo and performed better than titanium at promoting healing and reducing inflammation. It may be a promising candidate for stapler pins in intestinal reconstruction.

Comparison of the effects of Mg-6Zn and titanium on intestinal tract in vivo.

To evaluate the different effects of Mg-6Zn alloy and Ti-3Al-2.5V alloy implants in intestinal tract healing, we compared these two different alloys with respect to their effect on a rat's intestinal tract, using serum magnesium, radiology, pathology and immunohistochemistry in vivo. It was found using the scanning electron microscope that the Mg-6Zn alloy began to degrade during the first week and that the Ti-3Al-2.5V alloy was non-degradable throughout the process. The Mg-6Zn alloy did not have an impact on serum magnesium. Superior to the Ti-3Al-2.5V alloy, the Mg-6Zn alloy enhanced the expression of transforming growth factor-β1 in healing tissue, and promoted the expression of both the vascular endothelial growth factor and the basic fibroblast growth factor, which helped angiogenesis and healing. The Mg-6Zn alloy reduced the expression of the tumor necrosis factor (TNF-α) at different stages and decreased inflammatory response, which may have been related to the zinc inhibiting TNF-α. In general, the Mg-6Zn alloy performed better than Ti-3Al-2.5V at promoting healing and reducing inflammation. The Mg-6Zn alloy may be a promising candidate for use in the pins of circular staplers for gastrointestinal reconstruction in medicine.

http://iopscience.iop.org/article/10.1088/1748-6041/9/2/025011/pdf

Comparison of the effects of Mg-6Zn and Ti-3Al-2.5V alloys on TGF-β/TNF-α/VEGF/b-FGF in the healing of the intestinal tract in vivo.

To investigate the initial mechanical strength and the degradation behaviour with the associated changes in mechanical properties of magnesium-based osteosynthesis implants, 30 rabbits were implanted with cylindrical pins of the alloys MgCa08 (magnesium with 08 wt% calcium), LAE442 (magnesium with 4 wt% lithium, 4 wt% aluminium and 2 wt% rare earths) and WE43 (magnesium with 4 wt% yttrium and 3 wt% rare earths) The implants were inserted into the medullary cavity of both tibiae After 3 and 6 months, each half of the animals was euthanized, respectively, and the implants were taken out A determination of volume, three-point bending tests, scanning electron microscopy (SEM) and energy dispersive X-ray analyses as well as metallographic and μ-computed tomography examinations were accomplished All implants were clinically well tolerated MgCa-implants showed the least initial strength and the highest loss in volume after 6 months SEM- and μ-computed tomography examinations revealed a pronounced pitting corrosion Therefore, their use as degradable implant material seems to be limited LAE442 has the best initial strength which seems to be sufficient for an application in weight-bearing bones The degradation behaviour is very constant However, possible unknown side effects of the rare earths have to be excluded in further investigations on biocompatibility Considering all results of WE43, its application as osteosynthesis material for fracture repair is ineligible due to its heterogeneous and unpredictable degradation behaviour

http://library.nmlindia.org/FullText/JMS45103624.pdf?origin=publication_detail

Annett Krause

Papers

Degradation behaviour and mechanical properties of magnesium implants in rabbit tibiae