Pilot biomechanical study of complex upper-limb movements in patients with RSA using inertial sensors: Feasibility of sport-specific gestures

Background: This study aimed to evaluate recovery of complex upper-limb movements from a kinematic and biomechanical perspective in patients undergoing Reverse Total Shoulder Arthroplasty (RSA), comparing movement quality during athletic gestures with healthy controls. Methods: Two groups were analyzed: patients with RSA and healthy individuals without shoulder pathology. Participants performed basic shoulder tasks (flexion-extension and abduction-adduction) and three athletic gestures of increasing complexity: boccia throw, golf swing, and padel víbora stroke. Kinematic data (joint angles, angular velocities, and accelerations) were collected using a wearable inertial motion analysis system (Movit System G1). Results: Controls demonstrated a greater range of motion (maximum joint angle: 184.0° vs. 144.03°), though differences were not statistically significant. Angular velocities and accelerations were largely comparable between groups, indicating that patients with RSA adopt conservative yet functional movement strategies. No significant differences were observed during the boccia throw or golf swing. The víbora stroke showed the highest variability but remained within functional limits in both groups. Conclusions: This pilot feasibility study suggests that patients with RSA can perform complex upper-limb and sport-specific movements with biomechanical patterns comparable to healthy individuals. Although limited by small sample size, large effect sizes indicate clinically relevant differences, supporting the need for larger, confirmatory studies.