Quantitative Analysis of Scapular Range of Motion and Kyphotic Angle Using IMU Sensors : A Preliminary Study of Reliability and Validity

In recent years, the prevalence of musculoskeletal disorders affecting the neck, shoulders, and lower back has significantly increased due to the extensive use of digital devices. Among these, the visual display terminal syndrome, associated with prolonged computer and smartphone usage, often leads to forward head posture and round shoulder posture, contributing to muscle imbalances, functional impairments, and pain. Traditional methods for assessing and correcting such postures lack real-time monitoring and precise evaluation capabilities. This study aims to examine the reliability and validity of inertial measurement unit (IMU) sensors in measuring scapular range of motion (ROM) and kyphotic angle of upper thoracic, comparing with a conventional goniometer and a 3D motion capture system. Healthy young adults participated in this study. Scapular ROMs including neutral, protraction, and retraction were measured using IMU sensors and a goniometer. Kyphotic angle of upper thoracic were measured by an IMU sensor and 3D motion capture system. Results indicated high reliability for repeated measurements with IMU sensors across different scapular movements. The validity of IMU sensors compared to goniometers showed high intraclass correlation coefficients, demonstrating good agreement. Additionally, IMU sensors effectively captured upper thoracic kyphosis angles, aligning closely with data from the 3D motion capture system. These findings suggest that IMU sensors are reliable and valid for monitoring scapular and thoracic movements, offering a promising tool for real-time assessment and intervention of musculoskeletal disorders related to forward head posture and round shoulder posture. This technology can enhance personalized healthcare by providing accurate and continuous monitoring, facilitating early detection, and targeted management of posture-related musculoskeletal issues.