生物可降解MgYREZr合金的研究进展

Recent Advances on Biodegradable MgYREZr Magnesium Alloy

近年来医用可降解镁合金在生物医用材料领域备受关注,其中以WE43为代表的MgYREZr合金以优异的综合性能受到研究者的青睐。本文综述了WE43合金的组织结构、力学性能、降解性能和生物相容性的研究进展,以及德国采用近似于WE43成分的MgYREZr合金制备的可降解镁合金骨钉所进行的临床实验结果。MgYREZr合金由于RE元素的存在,组织均匀,经过大塑性变形可获得尺寸<1mm的晶粒,具有较高的抗拉强度、屈服强度及延伸率等力学性能;合金中的RE元素可以稳定腐蚀层,通过合理的热处理制度可以显著降低合金的降解速率。动物实验表明,合金具有良好的生物相容性及高的生物活性;临床实验显示,MgYREZr合金螺钉在治疗踇外翻的手术中具有与钛合金螺钉相同的治疗效果,而在腕舟骨骨折固定术中却发现了螺钉周围的骨溶解现象,导致病人的开始活动时间延至半年后。MgYREZr合金作为内植入物材料具有良好的综合力学性能和较高的耐蚀性,然而,针对不同的临床适应症,MgYREZr合金所制备器件的降解行为、生物学行为等还需要大量的体内外实验研究;进一步控制MgYREZr螺钉的降解速率以适应不同的临床需求,依然是其拓展临床应用范围所面临的主要问题。

In recent years, magnesium and its alloys as biodegradable materials have attracted much attention. Biodegradable Mg YREZr, mainly WE43 alloy, with good integrated properties has been studied in favor. In this paper, the microstructure, mechanical properties, biodegradable property and biocompatibility of biodegradable Mg YREZr alloy were reviewed, as well as the clinical results of the bone fixation screws developed in Germany using the alloy with similar composition to WE43. Mg YREZr alloy presents uniform microstructure and higher mechanical properties after large plastic deformation with the grain size of less than 1 mm. The RE elements can be dissolved and stabilize the corrosion layer, which can decrease the degradation rate of the alloy accompanying with optimized heat treatment. The animal tests showed biocompatibility and good bioactivity. Clinical tests showed the Mg YREZr alloy screws presented equivalent to titanium screws for the treatment of mild hallux valgus deformities, howeverresorption cysts was revealed by X-rays when the acute scaphoid fractures were treated with a doublethreaded screw made of Mg YREZr, and it was only after 6 months that the fractures were consolidated enough to allow physical work. So for different clinical cases, the degradation and biological behaviors of Mg YREZr alloys need to be further studied in vitro and in vivo. To control the degradation rates to meet the different clinical requirements is still a major obstacle for biodegradable Mg YREZr alloys to enlarge their clinical application.