Project Summary/Abstract Osteoarthritis (OA) is the most common form of arthritis and is prevalent in many joints, including the joints of the hand. In order to increase the understanding of hand OA, it is necessary to understand the natural structure of these joints. Radiography is commonly used in the scientific and clinical evaluation which can include joint space width (JSW) measurement, which can progressively decline due to cartilage deterioration. When considering demographics, these JSW measures have the potential to be different, given the diversity of living conditions. With respect to the hand, radiographic JSW is more easily discernable in the finger joints, as opposed to the thumb; specifically, the thumb carpometacarpal joint (CMC), where the complex morphology can render 2D visualization challenging. However, with computed tomography (CT), the joint can be viewed in 3D and the JSW more readily assessed. With these factors to consider, the specific aims of this project are: (1) Establish age-specific distribution percentiles for JSW in the finger joints of African Americans and Whites, separately for men and women, for two time points, using data from the Osteoarthritis Initiative (OAI); and (2) Establish reference values and demographic distributions for the thumb CMC JSW using CT and evaluate the relationship with 2D radiographic JSW measurement. Aim 1 will utilize data from the OAI for approximately 3500 hand radiographs. These radiographs will be evaluated for JSW at two time points and separated by age, race and gender. For Aim 2, a cohort of 25 males and 25 females will be recruited. A radiograph and CT scan of each of the participant hands will be taken. 3D models will be constructed from the CT images, from which CMC JSW measurements will be made and similar demographic information will be drawn. The CT measurements will then be used to identify landmarks on the radiographic images to make the 2D JSW measurement. Statistical comparisons will be drawn between the two measurements and the results will be used in the formulation of novel relationships suitable for adjusting the 2D measurements for agreement with the 3D measurements. Ultimately, this work will result in the quantification of JSW for the entire hand. The longitudinal data for the finger joints will support the goals of the parent project in the future development of predictive models for OA development for at-risk populations. The framework developed for the thumb can be expanded for a larger population for the development of similar predictive models. This project supports the career development of the candidate by initiating research focused on the use of engineering processes and medical imaging, for the development of computational models which can be used to evaluate the mechanics of healthy and arthritic joints.