Inertial Measurement Units for Clinical Movement Analysis: Reliability and Concurrent Validity

TLDR

The study aimed to assess the reliability and concurrent validity of the Xsens MVN BIOMECH inertial‑sensor motion capture system during clinically relevant functional activities. Twenty‑six healthy participants were evaluated by a novice clinician and an experienced movement scientist in two sessions separated by about four days, using both a camera‑based system and the MVN BIOMECH system while walking, squatting, and jumping; reliability was quantified with ICC and SEM, and validity with coefficient of multiple correlation and linear fit. Day‑to‑day reliability was fair‑to‑excellent for hip, knee, and ankle joint angles across all planes and tasks, within‑day between‑rater reliability was fair‑to‑excellent for walking and squatting but poor‑to‑high for jumping, and validity was excellent in the sagittal plane and acceptable in frontal and transverse planes, indicating the MVN BIOMECH system can reliably quantify lower‑limb joint angles in clinical movements.

Abstract

The aim of this study was to investigate the reliability and concurrent validity of a commercially available Xsens MVN BIOMECH inertial-sensor-based motion capture system during clinically relevant functional activities. A clinician with no prior experience of motion capture technologies and an experienced clinical movement scientist each assessed 26 healthy participants within each of two sessions using a camera-based motion capture system and the MVN BIOMECH system. Participants performed overground walking, squatting, and jumping. Sessions were separated by 4 ± 3 days. Reliability was evaluated using intraclass correlation coefficient and standard error of measurement, and validity was evaluated using the coefficient of multiple correlation and the linear fit method. Day-to-day reliability was generally fair-to-excellent in all three planes for hip, knee, and ankle joint angles in all three tasks. Within-day (between-rater) reliability was fair-to-excellent in all three planes during walking and squatting, and poor-to-high during jumping. Validity was excellent in the sagittal plane for hip, knee, and ankle joint angles in all three tasks and acceptable in frontal and transverse planes in squat and jump activity across joints. Our results suggest that the MVN BIOMECH system can be used by a clinician to quantify lower-limb joint angles in clinically relevant movements.