Validity and repeatability of a new inertial measurement unit system for gait analysis on kinematic parameters: comparison with an optoelectronic system

Abstract : Inertial measurement unit (IMU) systems are offering promising alternatives to optoelectronic systems for measuring human movement. The objective of this study was to assess the validity of a new inertial measurement system, iSen STT-IWS sensors, with reference to the optoelectronic motion capture system OptiTrack. 22 young participants performed three minutes of treadmill walking at different speeds. Hip, knee and ankle joint angles in the sagittal plane were compared between the two systems. Accuracy and repeatability of iSen IMU measures was evaluated with the Root Mean Square Deviation (RMSD) and Lin’s Concordance Correlation (LCC). A good to tolerable Isen measures’ accuracy was found (RMSD < 10°, LCC > 0.75) and reliability decreased with walking speed. Results indicated excellent test-retest repeatability of the inertial system (Intraclass correlation (ICC) > 0.75). Sagittal kinematic gait estimation using the iSen IMU system can be reliably used for clinical purposes on older adults.