State Key Laboratory for Turbulence and Complex System and Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing, People's Republic of China.
Acta Biomater. 2012 Jul;8(6):2360-74. doi: 10.1016/j.actbio.2012.02.018. Epub 2012 Mar 2.
Magnesium alloys have shown potential as biodegradable metallic materials for orthopedic applications due to their degradability, resemblance to cortical bone and biocompatible degradation/corrosion products. However, the fast corrosion rate and the potential toxicity of their alloying element limit the clinical application of Mg alloys. From the viewpoint of both metallurgy and biocompatibility, strontium (Sr) was selected to prepare hot rolled Mg-Sr binary alloys (with a Sr content ranging from 1 to 4 wt.%) in the present study. The optimal Sr content was screened with respect to the mechanical and corrosion properties of Mg-Sr binary alloys and the feasibility of the use of Mg-Sr alloys as orthopedic biodegradable metals was investigated by in vitro cell experiments and intramedullary implantation tests. The mechanical properties and corrosion rates of Mg-Sr alloys were dose dependent with respect to the added Sr content. The as-rolled Mg-2Sr alloy exhibited the highest strength and slowest corrosion rate, suggesting that the optimal Sr content was 2 wt.%. The as-rolled Mg-2Sr alloy showed Grade I cytotoxicity and induced higher alkaline phosphatase activity than the other alloys. During the 4 weeks implantation period we saw gradual degradation of the as-rolled Mg-2Sr alloy within a bone tunnel. Micro-computer tomography and histological analysis showed an enhanced mineral density and thicker cortical bone around the experimental implants. Higher levels of Sr were observed in newly formed peri-implant bone compared with the control. In summary, this study shows that the optimal content of added Sr is 2 wt.% for binary Mg-Sr alloys in the rolled state and that the as-rolled Mg-2Sr alloy in vivo produces an acceptable host response.
镁合金因其可降解性、与皮质骨相似以及可生物降解/腐蚀产物的生物相容性而被认为是一种有潜力的可生物降解的金属骨科材料。然而，其合金元素的快速腐蚀率和潜在毒性限制了镁合金的临床应用。从冶金学和生物相容性的角度来看，本研究选择锶（Sr）来制备热轧 Mg-Sr 二元合金（Sr 含量范围为 1 至 4wt.%）。根据 Mg-Sr 二元合金的力学性能和腐蚀性能以及 Mg-Sr 合金作为骨科可生物降解金属的可行性，筛选出最佳 Sr 含量，通过体外细胞实验和髓内植入试验进行了研究。Mg-Sr 合金的力学性能和腐蚀速率与添加的 Sr 含量呈剂量依赖性。热轧 Mg-2Sr 合金表现出最高的强度和最慢的腐蚀速率，表明最佳 Sr 含量为 2wt.%。热轧 Mg-2Sr 合金表现出 I 级细胞毒性，并比其他合金诱导出更高的碱性磷酸酶活性。在 4 周的植入期间，我们观察到在骨隧道内逐渐降解热轧 Mg-2Sr 合金。微计算机断层扫描和组织学分析显示，实验植入物周围的矿物质密度增加，皮质骨变厚。与对照相比，在新形成的植入物周围骨中观察到更高水平的 Sr。综上所述，本研究表明，在热轧状态下，二元 Mg-Sr 合金中添加 Sr 的最佳含量为 2wt.%，体内热轧 Mg-2Sr 合金产生可接受的宿主反应。
