Reproducibility and Validity of Lateral Knee Joint Sway Measurements During Walking Using Markerless Motion Capture

Abstract

This purpose of this study was to investigate the reproducibility and validity of the maximum knee varus angle during the initial ground contact and stance phases. Evaluations were performed during gait, when the knee varus angle changed from the stance phase from the knee varus angle of initial ground contact. We used markerless and optical motion capture in 30 limbs of 16 patients with knee OA. For reproducibility, the intraclass correlation coefficient was determined, and the Bland-Altman analysis was used for absolute reliability. Pearsonʼs correlation coefficient was used to examine the relationship between the measurements. The results of the analysis showed that the knee varus angle and its change during the initial ground contact and stance phases were highly reproducible. In addition, strong positive correlations were observed between measured values. Furthermore, the Bland-Altman analysis showed a fixed error between the measurements of each method. Our findings reveal that markerless motion capture provides a simple and quantitative method for measuring lateral knee joint sway during gait, thus ensuring the reliability and validity of the measured values.