Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016, China.
Mater Sci Eng C Mater Biol Appl. 2013 Oct;33(7):3881-8. doi: 10.1016/j.msec.2013.05.023. Epub 2013 May 18.
Magnesium alloys were studied extensively as a class of biodegradable metallic materials for medical applications. In the present study, ZK60 magnesium alloy was considered as a candidate and the micro-arc oxidation (MAO) treatment was adopted in order to reduce the degradation rate of the alloy. The in vivo degradation behaviors and biological compatibilities of ZK60 alloys with and without MAO treatment were studied with a transcortical model in rabbits. The implant and the surrounding bone tissues were characterized by CT, SEM and histological methods at 2, 4 and 12 weeks after the implantation. The results demonstrated that both the bare and MAO-coated ZK60 alloys completely degraded within 12 weeks in this animal model. The MAO coating decreased the degradation rate of ZK60 alloy and enhanced the response of the surrounding tissues within the first 2 weeks. After then, an acceleration of the degradation of the MAO-coated ZK60 alloy was observed. It was found that the alloy could be degraded before the complete degradation of the MAO coating, leading to the local peeling off of the coating. An in vivo degradation mechanism of the MAO-coated ZK60 alloy was proposed based on the experimental results. The severe localized degradation caused by the peeling off of the MAO coating was the main reason for the acceleration of the degradation of the MAO-coated ZK60 alloy.
镁合金作为一类可生物降解的金属材料，在医学应用中得到了广泛的研究。本研究选用 ZK60 镁合金作为候选材料，并采用微弧氧化（MAO）处理来降低合金的降解速率。通过兔皮质骨模型研究了未经 MAO 处理和经 MAO 处理的 ZK60 合金的体内降解行为和生物相容性。植入后 2、4 和 12 周，采用 CT、SEM 和组织学方法对植入物和周围骨组织进行了表征。结果表明，在该动物模型中，裸 ZK60 合金和 MAO 涂层 ZK60 合金均在 12 周内完全降解。MAO 涂层降低了 ZK60 合金的降解速率，并在前 2 周增强了周围组织的反应。随后，观察到 MAO 涂层 ZK60 合金的降解加速。发现合金在 MAO 涂层完全降解之前就可以降解，导致涂层局部剥落。根据实验结果提出了 MAO 涂层 ZK60 合金的体内降解机制。MAO 涂层剥落引起的严重局部降解是加速 MAO 涂层 ZK60 合金降解的主要原因。
