Step Count as a Digital Mobility Outcome—A Pilot Study on Differences Between the Upper and Lower Extremities

Background: Fractures of the lower extremity are commonly associated with impaired mobility, whereas injuries of the upper extremity primarily affect limb-specific function. Wearable devices allow the objective and continuous monitoring of physical activity and may therefore provide additional insight into postoperative recovery processes under real-world conditions. This exploratory study aimed to compare postoperative trajectories of daily step count following surgical treatment of upper versus lower extremity fractures and to explore possible associations with general health status and return to work. Methods: In this prospective observational study, 38 patients with upper extremity fractures and 55 patients with lower extremity fractures were included. Daily step counts were recorded postoperatively. Patient-reported general health (PROMIS Global Health) and work status at three months were assessed. Results: During the early postoperative period, patients with lower extremity injuries recorded lower daily step counts than patients with upper extremity injuries. Within three months, 89% of patients with upper extremity injuries and 49% of patients with lower extremity injuries had returned to work. Conclusions: In this exploratory cohort, postoperative step count trajectories differed between surgically treated upper and lower extremity fractures during the early postoperative period. Return-to-work rates at three months also differed between groups. Interpretation of these findings is limited by the real-world use of heterogeneous consumer wearable devices and the exploratory study design. These findings should be considered preliminary and hypothesis-generating.