Adult spinal deformity (ASD) is a common spinal condition that often impacts an individual's ability to stand and maintain an upright posture. Poor balance often limits an individual's ability to perform basic activities of daily life (ADL) and can lead to disability. Current considerations of correcting ASD to improve balance focus on the amount of sway that one exhibits during normal standing. However, current tests do not provide insight into the limits of balance during normal ADL. The goal of this research is to develop a new balance assessment that includes a functional reach test (FRT) to provide numerical data on the limits of one's ability to maintain balance. The study will include both ASD patients and matched healthy adults and will compare postural sway measures between them. Wearable motion tracking sensors and a force plate will be used to monitor body movement and changes in the center of pressure under foot during normal standing and during a FRT. Data from this study will inform spine surgeons of ASD patient's risk of balance loss in daily life and enable further research on the effects of surgical techniques to restore balance among ASD surgery patients.