Yen-Ting Chen1, Fei-Yi Hung2, Yen-Ling Lin1, Chia-Yen Lin3. 1. Department of Materials Science and Engineering, National Cheng Kung University, Tainan, Taiwan. 2. Department of Materials Science and Engineering, National Cheng Kung University, Tainan, Taiwan. Electronic address: fyhung@mail.ncku.edu.tw. 3. Ting Sin Co., Ltd., Tainan, Taiwan.
Abstract
BACKGROUND: Magnesium alloy implants have lower stress load and can be absorbed gradually, but their degradation rates are too fast generally. A magnesium alloy contained 5% Zn and 0.5% Zr (ZK50) which have lower degradation rate are designed to be applied to cannulated bone screw. METHODS: An oxidation heat treatment of 380 °C for 2 h proceeds to modify the ZK50 Mg alloy (ZK50-H). The microstructure observation, degradation tests and Biocompatibility analysis are proceeded between ZK50 and ZK50-H. Finally, a mini-pig implantation test is proceeded to provide a reference of implant application for future pre-clinical evaluation. RESULTS: The heat treatment can improve the mechanical properties. A passive ceramic layer formed after simulated body fluid (SBF) solution immersion can restrict the degradation effectively. The cytotoxicity test shows the initial biosafety of ZK50 Mg alloy. A mini-pig implantation test of bone screw has proceeded to confirm the advanced biocompatibility. The ZK50-H screws can maintain enough support at least 8 weeks which the fracture of bone can get curing. The excellent osteoinduction of ZK50-H has a positive effect to growth of new bones and help the mini-pig regain heal faster in 12 weeks. CONCLUSION: This study shows ZK50-H Mg alloy screw is a feasible degradation implant and can be carried out the next-step clinical experiments.
BACKGROUND:Magnesium alloy implants have lower stress load and can be absorbed gradually, but their degradation rates are too fast generally. A magnesium alloy contained 5% Zn and 0.5% Zr (ZK50) which have lower degradation rate are designed to be applied to cannulated bone screw. METHODS: An oxidation heat treatment of 380 °C for 2 h proceeds to modify the ZK50 Mg alloy (ZK50-H). The microstructure observation, degradation tests and Biocompatibility analysis are proceeded between ZK50 and ZK50-H. Finally, a mini-pig implantation test is proceeded to provide a reference of implant application for future pre-clinical evaluation. RESULTS: The heat treatment can improve the mechanical properties. A passive ceramic layer formed after simulated body fluid (SBF) solution immersion can restrict the degradation effectively. The cytotoxicity test shows the initial biosafety of ZK50 Mg alloy. A mini-pig implantation test of bone screw has proceeded to confirm the advanced biocompatibility. The ZK50-H screws can maintain enough support at least 8 weeks which the fracture of bone can get curing. The excellent osteoinduction of ZK50-H has a positive effect to growth of new bones and help the mini-pig regain heal faster in 12 weeks. CONCLUSION: This study shows ZK50-H Mg alloy screw is a feasible degradation implant and can be carried out the next-step clinical experiments.