Biodegradable implants are taking an increasingly important role in the area of orthopedic implants with the aim to replace permanent implants for temporary bone healing applications. During the implant preparation process, the material's surface and microstructure are being changed by stresses induced by machining. Hence degradable metal implants need to be fully characterized in terms of the influence of machining on the resulting microstructure and corrosion performance.

In this study, micro-computed tomography (µCT) is used for the quantification of the degradation rate of biodegradable implants. To our best knowledge, for the first time quantitative measures are introduced to describe the degradation homogeneity in 3D. This information enables a prediction in terms of implant stability during the degradation in the body.

Two magnesium gadolinium alloys, Mg-5Gd and Mg-10Gd (all alloy compositions are given in weight% unless otherwise stated), in the shape of M2 headless screws have been investigated for their microstructure and their degradation performance up to 56 days. During the microstructure investigations particular attention was paid to the localized deformation of the alloys, due to the machining process. In vitro immersion testing was performed to assess the degradation performance quantified by subsequent weight loss and volume loss (using µCT) measurements.

Although differences were observed in the degree of screw's near surface microstructure being influenced from machining, the degradation rates of both materials appeared to be suitable for application in orthopedic implants. From the degradation homogeneity point of view no obvious contrast was detected between both alloys. However, the higher degradation depth ratios between the crests and roots of Mg-5Gd ratios may indicated a less homogeneous degradation of the screws of these alloys on contract to the ones made of Mg-10Gd alloys. Due to its lower degradation rates, its more homogeneous microstructure, its weaker texture and better degradation performance extruded Mg-10Gd emerged more suitable as implant material than Mg-5Gd.

可生物降解的植入物在骨科植入物领域发挥着越来越重要的作用，旨在替代永久性植入物用于临时骨愈合应用。在种植体制备过程中，材料的表面和微观结构会因加工产生的应力而发生变化。因此，需要根据加工对所得微观结构和腐蚀性能的影响来全面表征可降解金属植入物。

在这项研究中，微计算机断层扫描 (μCT) 用于量化可生物降解植入物的降解率。据我们所知，这是第一次引入定量测量来描述 3D 中的降解均匀性。该信息能够在体内降解期间根据植入物的稳定性进行预测。

研究了 M2 无头螺钉形状的两种镁钆合金 Mg-5Gd 和 Mg-10Gd（除非另有说明，否则所有合金成分均以重量百分比表示）的微观结构和降解性能长达 56 天。在微观结构研究期间，特别注意合金的局部变形，这是由于加工过程造成的。进行体外浸泡测试以评估通过随后的重量损失和体积损失（使用 µCT）测量量化的降解性能。

尽管观察到螺钉近表面微观结构受加工影响的程度存在差异，但两种材料的降解率似乎都适用于骨科植入物。从降解均匀性的角度来看，两种合金之间没有检测到明显的对比。然而，Mg-5Gd 比率的峰顶和根部之间较高的降解深度比率可能表明这些合金的螺钉与由 Mg-10Gd 合金制成的螺钉相比，其降解更不均匀。由于其较低的降解率、更均匀的微观结构、更弱的质地和更好的降解性能，挤压成型的 Mg-10Gd 比 Mg-5Gd 更适合作为植入材料。