PROJECT SUMMARY Neck pain (NP) is the 3rd most common chronic pain condition in the U.S. and the 4th leading cause of disability worldwide. Despite the prevalence and significant disability and financial burden, there is still an unclear understanding of the biological mechanisms, although growing evidence suggests a biomechanical element. There is a critical need to enhance our understanding of NP mechanisms and improve treatment outcomes. Our broad long-term research initiative is to develop an objective biomarker for spinal health based on aberrant movement patterns, a measure of instability, to enhance our understanding of NP mechanisms and improve treatment outcomes. The central hypotheses are a) intersegmental spinal instability, or aberrant motion, is a primary mechanism of mechanical neck pain and b) neuroforaminal impingement is a primary mechanism of neck pain with radiculopathy and is exacerbated by movement. In AIM 1, 3D cervical spine intersegmental motion via biplanar fluoroscopy during physiological loading activities will be collected on patients with NP and asymptomatic age/sex matched controls to determine the extent their motion differs. In AIM 2, multi-dimensional interactions between biomechanical data and clinical measures will be explored through an interactive visualization-based approach. Capitalizing on state-of-the-art technology and unique visualization techniques, this interdisciplinary research will provide novel critical insights into the mechanisms of NP. The synthesis of intersegmental spinal motion during physiological loading conditions provides the ability to quantify cervical motion for the first time and develop an objective movement dysfunction based tool.