Validity and reliability of inertial measurement units in active range of motion assessment in the hip joint

Abstract

AbstractMeasuring joint range of motion has traditionally occurred with a universal goniometer, inclinometer, or expensive laboratory systems. The popularity of the inertial measuremen unit (IMU) is growing, enabling the small even single portable device to measure the range of motion. Until now, they were not used to assess hip joint range of motion. Our study aimed to check the validity of IMU in assessing a hip range of motion and compare them to other measurement devices - universal goniometer and inclinometer. Twenty participants completed three hip movements (flexion in standing and prone internal and external rotation) on both hips. Two testers independently assessed each movement with a goniometer, digital inclinometer, and IMU at different time points. To assess the agreement of active hip ROM between devices, Intraclass Correlation Coefficient (ICC) and Bland-Altman analysis were used. Furthermore, inter-rater and intra-rater reliability were also assessed by using ICC and Bland-Altman analysis. Limits of agreement (LOA) were calculated using Bland-Altman plots. IMU showed good to excellent validity compared with the goniometer and digital inclinometer for all tested movements with ICCs ranging from 0.87-0.99 and LOAs <9°. Intra-rater reliability was good-to-excellent for all tested movements for all devices, with ICCs ranging from 0.87 to 0.99 and LOAs < 7°. Inter-rater reliability was lower and comparable for all measurement methods: moderate flexion (ICC: 0.58-0.59), LOAs <22,4 and poor for both rotations (ICC:-0.33-0.04), and LOAs < 7.8°). The present study shows that a single inertial measurement unit (RSQ Motion) could be successfully used to assess the active hip range of motion in healthy subjects with comparable to other methods accuracy.