The effect of foot position on hip and ankle kinematics and kinetics during walking in static calibration trials.

Three-dimensional gait analysis has been used extensively in research. During walking, the external hip adduction moment (EHAM) has been used as a surrogate measure of joint loading in individuals with hip osteoarthritis and inconsistency between previous studies could be attributed to the inconsistency of static standing trials. The present study was designed to examine the effects of static trial foot position on hip and ankle kinetics and kinematics variables during walking. Twelve participants were recruited and completed three static trials: 20° toe-out, straight (0°), and 20° toe-in. Five walking trials (own pace and shoes) were collected. The dynamic trials were analysed using three static trials. The first-peak, trough, and second-peak EHAMs and other hip and ankle kinematics and kinetics were compared between the conditions using repeated-measures analysis of variance. The first peak, trough, and second peak EHAMs showed a significant increase during movement from 20° toe-in to 20° toe-out by 5.87 %, 7.74 %, and 7.68 %, respectively. Furthermore, significant changes were found in hip flexion angle, hip sagittal plane range of motion angle, hip adduction and abduction angles, hip internal and external rotation angles, hip internal rotation moment, ankle dorsiflexion and plantarflexion moments, and ankle inversion and eversion moments. In this study, the change in foot position during the within-subject trials affected the first peak, trough, and second peak EHAMs and other kinetic and kinematic variables during walking. Therefore, this study highlights the importance to standardise the foot position in static trials to avoid masking or accentuating the actual changes.