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

该NSF教师早期职业发展（CAREER）计划拨款将开发一项研究和教育计划，预计将确定和预测骨质疏松症中发生的骨组织成分变化如何影响骨折行为。该研究计划预计将阐明骨质疏松性骨折的根本原因，并有助于确定诊断指标。这对社会和美国经济具有重要的潜在利益，因为髋部骨折是残疾的重要原因，预防脆性骨折是减少美国医疗保健支出的一个巨大且不断增长的部分的机会。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）扩大代表性不足的群体的参与，并在促进教学，培训，和学习，通过从事长期代表性不足的少数民族大学生，尽管骨质疏松症已知会导致骨组织成分的病理变化，而这些变化在统计学上与脆性相关骨折，骨组织组成的病理变化影响骨折风险的机制尚不清楚。本项目的目的是将微观组成中的病理变化的影响与骨中毫米长度尺度的断裂行为机械地联系起来。特别是，我们解决了材料特性的微观变化，即，异质性，这正在成为骨韧性的重要贡献者。研究方法是建立成分纳米力学性能的关系，映射属性在皮质组织的样本，跨越广泛的宏观髋部骨折形态。然后，研究小组将创建样本的有限元模型，结合材料特性的特定分布，以预测更大长度尺度下的断裂行为。这项工作是变革性的，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.