Iskhakova Kamila, Wieland D C Florian, Marek Romy, Schwarze Uwe Y, Davydok Anton, Cwieka Hanna, AlBaraghtheh Tamadur, Reimers Jan, Hindenlang Birte, Sefa Sandra, Lopes Marinho André, Willumeit-Römer Regine, Zeller-Plumhoff Berit
Institute of Metallic Biomaterials, Helmholtz-Zentrum Hereon, Max-Planck-Straße 1, 21502 Geesthach, Germany.
Department of Orthopaedics and Traumatology, Medical University of Graz, Auenbruggerplatz 5, 8036 Graz, Austria.
J Funct Biomater. 2024 Jul 12;15(7):192. doi: 10.3390/jfb15070192.
Magnesium alloys are some of the most convenient biodegradable materials for bone fracture treatment due to their tailorable degradation rate, biocompatibility, and mechanical properties resembling those of bone. Despite the fact that magnesium-based implants and ZX00 (Mg-0.45Zn-0.45Ca in wt.%), in particular, have been shown to have suitable degradation rates and good osseointegration, knowledge gaps remain in our understanding of the impact of their degradation properties on the bone's ultrastructure. Bone is a hierarchically structured material, where not only the microstructure but also the ultrastructure are important as properties like the local mechanical response are determined by it. This study presents the first comparative analysis of bone ultrastructure parameters with high spatial resolution around ZX00 and Ti implants after 6, 12, and 24 weeks of healing. The mineralization was investigated, revealing a significant decrease in the lattice spacing of the (002) Bragg's peak closer to the ZX00 implant in comparison to Ti, while no significant difference in the crystallite size was observed. The hydroxyapatite platelet thickness and osteon density demonstrated a decrease closer to the ZX00 implant interface. Correlative indentation and strain maps obtained by scanning X-ray diffraction measurements revealed a higher stiffness and faster mechanical adaptation of the bone surrounding Ti implants as compared to the ZX00 ones. Thus, the results suggest the incorporation of Mg ions into the bone ultrastructure, as well as a lower degree of remodeling and stiffness of the bone in the presence of ZX00 implants than Ti.
镁合金是用于骨折治疗的一些最便利的可生物降解材料，这是由于其可定制的降解速率、生物相容性以及与骨骼相似的机械性能。尽管镁基金属植入物，特别是ZX00（重量百分比为Mg-0.45Zn-0.45Ca）已被证明具有合适的降解速率和良好的骨整合性，但我们对其降解特性对骨骼超微结构的影响的理解仍存在知识空白。骨骼是一种具有层次结构的材料，其中不仅微观结构而且超微结构都很重要，因为诸如局部力学响应等特性是由其决定的。本研究首次对愈合6周、12周和24周后围绕ZX00和钛植入物的具有高空间分辨率的骨骼超微结构参数进行了比较分析。对矿化情况进行了研究，结果显示与钛相比，靠近ZX00植入物处（002）布拉格峰的晶格间距显著减小，而微晶尺寸未观察到显著差异。羟基磷灰石薄片厚度和骨单位密度在靠近ZX00植入物界面处呈下降趋势。通过扫描X射线衍射测量获得的相关压痕和应变图显示，与ZX00植入物周围的骨骼相比，钛植入物周围的骨骼具有更高的刚度和更快的力学适应性。因此，结果表明镁离子融入了骨骼超微结构，并且在存在ZX00植入物的情况下，骨骼的重塑程度和刚度低于钛植入物周围的骨骼。
