Scapular kinematics are associated with pain duration, age, and place of residence in subacromial pain syndrome

Subacromial pain syndrome (SAPS) is a prevalent upper limb musculoskeletal disorder. Although scapular kinematics changes are associated with SAPS, studies show varied, often inconclusive patterns. Factors like pain duration and rural residence, which are associated with limited access to care and greater arm demands, may explain these results. The purpose of this study was to investigate how pain duration, age, sex, and place of residence influence scapular kinematics in individuals with SAPS. Sixty participants from urban and rural areas with SAPS were recruited, and upper body motion was tracked during an overhead reach task. Scapular angles were extracted at specific humeral elevation levels. Robust mixed linear regression models examined relationships between scapular angles and independent variables. Older (>35) rural, younger (≤35) urban, and younger rural groups showed lower upward rotation and higher internal rotation with longer pain duration, indicating scapular kinematics may be associated with SAPS progression. The older urban group showed opposite kinematic relationships, possibly due to differing arm demands. Internal rotation increased with age, and upward rotation varied with sex for all conditions except at maximum humeral elevation, regardless of pain duration. Scapular kinematics are related to pain duration, age, and residence, potentially contributing to pain status or progression. Future research should consider pain duration and individual factors, such as age and arm demand, when studying kinematic alterations in persons with SAPS.