Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100083, China; Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing 100083, China.
Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100083, China; Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing 100083, China.
Acta Biomater. 2019 Jan 1;83:477-486. doi: 10.1016/j.actbio.2018.11.019. Epub 2018 Nov 13.
Magnesium-based implants are subjected to complicated stresses during implantation in the human body. The stress effects on corrosion of magnesium (Mg) in vitro were investigated in previous studies, whereas in this study, the corrosion behaviors of high-purity (HP) Mg under stress were comparatively studied in vitro in Hank's solution and in vivo in the subcutaneous environment of rats. Loading devices were designed to apply compressive stress (15.1 ± 0.5 MPa) and tensile stress (13.2 ± 0.2 MPa) on HP Mg specimens both in vitro and in vivo. Corrosion rates of HP Mg were characterized by mass and volume losses. It was shown that the applied compressive stress had no effect on in vitro corrosion behaviors and the applied tensile stress accelerated the in vitro corrosion, thereby causing severe pitting corrosions and stress corrosion cracking (SCC). However, there was no significant change for corrosion behaviors in vivo under neither compressive stress nor tensile stress. Severe pitting corrosion and SCC did not occur in vivo. Histological evaluation revealed that a fibrotic capsule induced by foreign body reaction was formed on the corrosion surfaces of HP Mg in the subcutaneous environment. It was proposed that the fibrotic capsule suppressed the effects of stress in vivo by protecting the corrosion surfaces. These results provided new insights into understanding the stress effects on the corrosion of Mg both in vitro and in vivo. STATEMENT OF SIGNIFICANCE: Mg and its alloys have shown potential as biodegradable metallic materials. During implantation, Mg is subjected to various mechanical environments in the human body. It is necessary to have a clear understanding of different effects of stress on Mg corrosion. However, few studies were performed in vivo. It is important to analyze the effect of quantitative stress on Mg corrosion in vivo. Therefore, in this study, quantitative stresses were applied on Mg both in vitro and in vivo. The effects of stress on in vitro and in vivo corrosions of Mg were investigated and compared.
镁基植入物在人体植入过程中会受到复杂的应力。以前的研究调查了这些应力对镁（Mg）体外腐蚀的影响，但在这项研究中，比较研究了高纯度（HP）Mg 在体外 Hank's 溶液和体内大鼠皮下环境中的受力腐蚀行为。设计了加载装置，以对 HP Mg 标本施加压缩应力（15.1±0.5 MPa）和拉伸应力（13.2±0.2 MPa），无论是在体外还是体内。通过质量和体积损失来表征 HP Mg 的腐蚀速率。结果表明，施加的压缩应力对体外腐蚀行为没有影响，而施加的拉伸应力加速了体外腐蚀，从而导致严重的点蚀腐蚀和应力腐蚀开裂（SCC）。然而，在体内，无论是压缩应力还是拉伸应力，腐蚀行为都没有明显变化。体内没有发生严重的点蚀腐蚀和 SCC。组织学评估显示，在皮下环境中，异物反应引起的纤维囊在 HP Mg 的腐蚀表面形成。提出纤维囊通过保护腐蚀表面来抑制体内的应力影响。这些结果为理解体外和体内 Mg 腐蚀的应力影响提供了新的见解。
镁及其合金已显示出作为可生物降解金属材料的潜力。在植入过程中，镁在人体内会受到各种机械环境的影响。有必要清楚地了解不同的应力对镁腐蚀的影响。然而，体内研究很少。分析体内定量应力对镁腐蚀的影响很重要。因此，在这项研究中，对镁进行了体外和体内的定量应力施加。研究并比较了应力对镁体外和体内腐蚀的影响。
