Analysis of tissue-material characteristics at the bone-magnesium interface built by biodegradable implants

需要为活跃的青少年患者群体和表现为创伤性骨折的成年人提供最佳医疗护理，例如，在参加体育活动后。在目前阶段，这类骨折采用不可降解的金属植入物治疗，有时必须取出，例如，植入物和生长中的骨之间可能会出现大小和形状不匹配的情况，特别是在生长过程中的儿童。这样的第二次手术干预伴随着额外的治愈期、潜在的并发症和对患者的副作用。由镁合金制成的可降解植入物具有很高的骨愈合潜力，因为这种植入物在恢复过程中会随着时间的推移而溶解。由于镁是天然存在于人体内的，而且镁合金的机械性能更接近人类骨骼，因此镁合金的生物相容性可能会进一步有利于愈合过程。由于种植体的降解，骨与种植体的界面不能再被认为是恒定的，因为它伴随着不断变化的化学环境而受到稳定的重塑。到目前为止，人们还不完全了解这种转变对骨整合的影响。因此，我们的目标是检测降解种植体对骨组织力学性能的影响，并将其与不同等级骨结构的变化联系起来。我们设计了一项研究计划，以测量镁种植体周围所需的纳米结构、化学和生物力学特性，通过加入提供全面骨表征(UKE)和生物可降解镁种植体(下文)专业知识的相关工作组的能力，破译由降解引起的不同等级长度尺度的变化。我们将利用组织学、元素图谱、纳米压痕和小角X射线散射实验来获得关于化学成分、机械性能以及微和纳米结构行为的信息。因此，将生成一个全面的数据集，将镁植入物周围的机械、结构和化学参数汇集在一起。对这个多模式数据集进行相关分析将使我们更好地了解哪些关键因素决定了在植入物与骨界面稳定重塑的情况下的骨整合，以及由此产生的骨基质特性如何依赖于此。这将有可能将骨组织的生物力学变化与种植体降解、降解产物的形成和动态变化的骨-种植体界面的结构适应联系起来。

Optimal medical care is required for active juvenile patient groups and adults exhibiting traumatic fractures, e.g., following sports activities. At the current stage, such fractures are treated with non-degradable metal implants that sometimes must be removed as, e.g., a mismatch in size and shape between the implant and growing bone can occur especially for children during growth. Such a second surgical intervention comes along with additional healing periods, potential complications, and side effects for the patient. Degradable implants made of magnesium (Mg) alloys provide a high potential for bone healing as such an implant dissolves with time during recovery. Magnesium alloys may further benefit the healing process due to their biocompatibility as Mg is naturally occurring in the body and Mg alloys mechanical properties are closer to those of human bone. Due to the degradation of the implant, the bone to implant interface can no longer be regarded as constant as it is subject to a steady remodelling alongside a changing chemical environment. Up to now, it is not fully understood how this transition impacts osseointegration. Therefore, we aim to examine the influence of degrading implants on the mechanical properties of the bone tissue and connect it to changes in the different hierarchical bone structures. We have designed a research program to measure the needed nanostructural, chemical, and biomechanical properties around Mg implants to decipher changes at different hierarchical length scales induced by degradation through joining the competencies of the involved workgroups providing the expertise of comprehensive bone characterization (UKE) and biological degradable magnesium implants (Hereon). We will utilize histology, elemental mapping, nanoindentation, and small-angle X-ray scattering experiments to obtain information on the chemical composition, mechanical properties, and micro- and nanostructural behaviour. As a result, a comprehensive dataset will be generated, bringing together mechanical, structural, and chemical parameters around Mg implants. Performing a correlative analysis on this multimodal dataset will allow us to understand better which key factors determine the osseointegration in the presence of a steadily remodelling implant to bone interface and how the resulting properties of the bone matrix depend on this. It will be possible to connect the bone tissue's biomechanical changes to structural adaptations during implant degradation, formation of degradation products, and dynamically changing bone-implant interface.