A wearable IMU-based medical assessment system for trunk motion: clinical validation and preliminary study

Abstract

Assessment of spinal range of motion (ROM) is essential in clinical practice, particularly in the management of low back pain (LBP), but current methods remain limited in their ability to efficiently evaluate spinal mobility and trunk devices effects. This observational cohort clinical validation study aimed to validate an inertial measurement unit (IMU)-based system for measuring spinal mobility and to assess its ability to detect the effects of two trunk devices, a lumbar belt and a posture shirt. Adult participants with no reported spinal pathology were assessed in an outpatient clinical laboratory setting. Three IMU sensors were placed at T1, T12, and S1 to measure spinal mobility during lateral trunk flexion. System performance was compared with a standard goniometer using intraclass correlation coefficients (ICC) and Bland-Altman analyses. In addition, the ability of the IMU-based system to discriminate between the effects of the lumbar belt and the posture shirt on trunk kinematics during sit-to-stand movement was evaluated using ANOVA. The IMU-based system showed excellent agreement with the goniometer (ICC = 0.96 for right lateral flexion and 0.90 for left lateral flexion), with clinically acceptable limits of agreement. It also distinguished between the two devices: the lumbar belt significantly reduced lordosis during sitting and standing and reduced trunk flexion during transition, whereas the posture shirt showed a more pronounced effect on thoracic kyphosis. These findings support the IMU-based system as a reliable tool for assessing spinal mobility and evaluating trunk therapeutic devices in clinical practice.