Toddlers with congenital limb deficiencies, such as fibular hemimelia, face major barriers to independent mobility during a critical window of motor development. This study presents a novel, user-centered approach to a modular pediatric lower limb orthoprosthesis dubbed +Limb. Functional evaluations demonstrated significant improvements, including correction of a 4.5 cm leg length discrepancy, reduction of pelvic tilt from 15° to 0°, and initiation of unassisted gait with controlled knee flexion up to 45°. To study how the body and muscles responded, different sensors were used, including pressure sensors (FSRs), muscle activity sensors (EMG), and a pressure plate for foot contact analysis. See more.