CAREER: Role of Variations in Tissue Material Properties in Bone Fracture Behaviors

美国国家科学基金会教师早期职业发展（Career）项目资助将开发一项研究和教育项目，旨在识别和预测骨质疏松症中骨组织成分的变化如何影响骨折行为。该研究计划有望阐明骨质疏松性骨折的潜在原因，并有助于确定其诊断指标。这对社会和美国经济都有重要的潜在好处，因为髋部骨折是导致残疾的重要原因，而预防脆性骨折代表了一个机会，可以减少美国大量且不断增长的医疗支出。该教育计划预计将通过以下方式造福社会：1)通过开发复合材料和生物材料的课程材料来加强教育基础设施，并将其纳入国家教材数据库；2)扩大代表性不足群体的参与，并在促进教学、培训、虽然骨质疏松症会引起骨组织组成的病理变化，而这在统计学上与脆性骨折有关，但骨组织组成的病理变化影响骨折风险的机制尚不清楚。这个项目的目的是机械地将微尺度组成的病理变化的影响与骨在毫米长度尺度上的骨折行为联系起来。特别是，我们解决了材料性能的微观变化，即非均质性，这是骨骼韧性的重要因素。研究方法是通过绘制样本皮质组织的属性来建立成分-纳米力学性能之间的关系，这些样本跨越了广泛的宏观髋部骨折形态。然后，研究团队将创建试样的有限元模型，结合材料特性的试样特定分布来预测更大长度尺度下的断裂行为。这项工作具有变革性，因为它通过将前一学科的患者数据与后一学科的严格建模相结合，将实验骨科研究与计算骨折力学相结合。

This NSF Faculty Early Career Development (CAREER) Program grant will develop a research and educational program that is expected to identify and predict how the changes in bone tissue composition that occur in osteoporosis will affect bone fracture behavior. The research program is expected to clarify the underlying causes of osteoporotic fractures and help to identify diagnostic indicators for them. This has important potential benefits for society and the US economy because hip fractures are an important cause of disability, and prevention of fragility fractures represents an opportunity to reduce a large and growing segment of healthcare expenditures in the US. The educational program is expected to benefit society by 1) enhancing infrastructure for education by developing curricular materials for composite materials and biomaterials, and making them available in a national database of teaching materials and 2) broadening participation of underrepresented groups and advancing discovery while promoting teaching, training, and learning by engaging underrepresented minority undergraduates in long-term research positions Although osteoporosis is known to cause pathologic changes in bone tissue composition that are statistically associated with fragility fracture, the mechanisms by which pathologic changes in bone tissue composition affect fracture risk are unknown. The objective of this project is to mechanistically link the effects of pathologic changes in microscale composition to fracture behavior at the millimeter length scale in bone. In particular, we address microscale variation in material properties, i.e., heterogeneity, which is emerging as an important contributor to bone toughness. The research approach is to establish composition-nanomechanical property relationships by mapping properties in cortical tissue from samples that span a wide spectrum of macroscopic hip fracture morphologies. Then, the research team will create finite element models of the specimens, incorporating specimen-specific distributions of material properties to predict fracture behavior at larger length scales. This work is transformative because it integrates experimental orthopedic research with computational fracture mechanics by combining patient data from the former discipline with the rigorous modeling of the latter discipline.