Adequately identifying patients at risk for osteoporotic fractures is a growing concern as our population ages. Our long term goal is to develop novel techniques, which in conjunction with bone mineral density (BMD), will better identify patients at risk for fracture and allow the clinical implementation of strategies to prevent fractures. The objective of the current study is to determine whether a novel minimally invasive method for in vivo measurement of cortical bone material properties can identify those who are at risk for fragility fractures of the hip and wrist. Our working hypothesis is that women with fragility fractures have altered cortical bone material properties that make them susceptible to these injuries. We further hypothesize that these altered bone matrix properties are not detectable with traditional testing methods, such as BMD. To test this hypothesis, we propose two aims: Aim 1) Determine whether women with hip fractures have altered cortical bone tissue properties, as assessed in vivo by a new minimally invasive approach called reference point indentation, compared to women without fractures; and Aim 2) Determine whether women with wrist fractures have altered cortical bone tissue properties, as assessed in vivo by reference point indentation compared to patients without fractures. We will compare cortical bone tissue properties, as assessed by in vivo reference point indentation at the mid-tibia, in three groups of postmenopausal women: 1) those with recent hip fractures (n=50); 2) those with recent wrist fractures (n=50) and 3) age-similar controls without a history of fracture (n=50). In addition, we will assess hip and spine BMD by DXA as well as clinical characteristics, including vitamin D status, medication history, and lifestyle factors (e.g., smoking, alcohol, and physical activity). Successful completion of this project will provide novel information about possible clinical utilit of minimally invasive, in vivo bone indentation measurements as a tool to assess fracture risk.