The problem of rapid degradation of PLA coated by Guangyu high strength pure magnesium bone nail
The problem of rapid degradation of PLA coated by Guangyu high strength pure magnesium bone nail
The main drawback of traditional magnesium bone nail is that "the degradation speed is too fast". Before the bone hyperplasia, the magnesium bone nail has been degraded and ablated. Since 2014, Taiwan Guangyu Technology Co., Ltd. has cooperated with the Taiwan metal center to carry out experiments. It uses high-purity magnesium materials to manufacture non-toxic magnesium bone nails and "encapsulates biodegradable polymer materials" to slow down the rapid degradation rate of traditional magnesium bone nails, and has successively obtained invention and utility model patents.
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The main drawback of the traditional magnesium bone nail is that "the degradation speed is too fast". Before the bone hyperplasia, the magnesium bone nail has been degraded and ablated. Since 2014, Taiwan Guangyu Technology Co., Ltd. has cooperated with the Taiwan metal center to carry out experiments. It uses high-purity magnesium materials to manufacture non-toxic magnesium bone nails and "encapsulates biodegradable polymer materials" to slow down the rapid degradation rate of traditional magnesium bone nails, and has successively obtained invention and utility model patents.


In order to solve the problem that the degradation rate is too fast, the AZ31 & ZK60 magnesium alloy was implanted into the femur of New Zealand white rabbits by alloying and surface treatment technology. It was found that ZK60 in untreated group had obvious air cavity performance in 1-2 weeks after implantation, and that in surface treated ZK60 was similar in 2 weeks after implantation, but gradually slowed down at 3 weeks after implantation. However, the air cavity performance of untreated group was still enlarged until 5 weeks after implantation. There was no significant air cavity in AZ31 group.
If alloy elements and surface treatment elements are to be used as biomedical materials, they may have unknown effects on human body. In order to avoid these unknown hazards, Guangyu technology research team used the simplest element (high-purity magnesium material) to develop high-strength magnesium bone nail to replace alloy element bone nail. In 2015, Guangyu obtained the patent of high-purity magnesium high-strength bone nail material
The literature points out: pure magnesium bone nail has no effect on the differentiation ability of stem cells, and its cell proliferation rate is much higher than other bone nail materials, which is safer and more effective (as shown in the figure). However, there is still a big difficulty in the development of high-purity magnesium bone nail: the degradation rate is too fast, and it can not support until the bone growth is completed.

In order to overcome this problem, Guangyu company continues to research and develop: to slow down the degradation rate by coating biodegradable polymer materials. Biodegradable polymer material (PLA) can be absorbed by human body and has no toxicity. It is one of the widely used biomedical materials. There are also commercial bone nails and plates in the market.
Comparing the advantages and disadvantages of the two materials: Pure Mg has the advantages of biocompatibility and high strength; disadvantages: the degradation rate is too fast and the degradation environment is alkaline. Polylactic acid (PLA) advantages: biocompatibility, can be produced by 3D printing; disadvantages: the degradation rate is too slow, the intensity is low, and the degradation environment is acidic.
The advantages of PLA coated pure magnesium bone nail can be obtained as follows:
1. They are non-toxic and biocompatible to human body.
2. Prolong the degradation time.
3. In the degradation process, the nail environment is neutral.
In terms of manufacturing technology, Guangyu has also obtained different utility model patents on both sides of the Strait. We use ultrasonic guiding head to connect screws and apply energy to make them produce phase change and dissolve embedded tissues. The pH test of pure magnesium and co culture of magnesium ions and cells showed that PLA coated pure magnesium bone nail could slow down the degradation and increase the strength of bone nail, and the heat conduction test of bone nail showed uniform conduction.
Biomedical cooperation is welcome.