Investigation of the validity and reliability of wearable motion sensors in knee joint movement meausurement

Joint range of motion (ROM) is one of the factors that determine the function of the musculoskeletal system. It should be able to be measured and recorded with an accurate and repeatable method. In this study, it is aimed to investigate whether measuring ROM in the knee joint with wearable motion sensors is a valid and reliable measurement method. The study was conducted with 70 healthy university students between the ages of 18-25 at the Department of Physiotherapy and Rehabilitation of the Faculty of Health Sciences of Haliç University between 15 December 2021 and 15 April 2022. Dominant knee ROM of the participants was measured separately with both digital goniometer (Meloq EasyAngle) and wearable motion sensors (MetaMotionRL). The first evaluator first evaluated knee joint active flexion angle; it was measured 3 times with a digital goniometer (Meloq EasyAngle) and the highest value was recorded. Two wearable motion sensors were fixed with velcro tape on the outer edge of the thigh and leg at the level of the midpoint of the tibia and femur in the dominant lower extremity. Active flexion angle of the knee joint was measured 3 times with MetamotionRL by the first evaluator and the highest value was recorded. The sensors were removed and reinserted within 10 minutes and measured a second time by the same evaluator with the same method, and the highest value was recorded. Following the removal of the sensors, the participant was taken to a different examination table in the same room, and after the application of the sensors, the second evaluator in accordance with the protocol performed the measurement 3 times and the highest value was recorded. Intra-rater and inter-rater reliability with the Intraclass Correlation (ICC) test; the concordance validity between goniometer and wearable motion sensor measurements was evaluated with the Spearman correlation test. Intra-rater (ICC p=0.000) and inter-rater (ICC p=0.000) reliability was found to be high in measurements made with the wearable motion sensor. A high correlation (Spearman rs=0.865, p=0.000) was observed between the active flexion angle of the knee measured with a digital goniometer and the measurement with the wearable motion sensor. In this study, it was concluded that active flexion angle range of motion measurement of the knee joint in healthy adults between 18-25 years of age by using MetamotionRL brand wearable motion sensors was a valid and reliable method. Keywords: Knee Range of Motion, MetamotionRL, Wearable Motion Sensors.