The effect of foot position during static calibration trials on knee kinematic and kinetics during walking

Background Gait analysis has been used extensively for computing knee kinematics and kinetics, in particular, in healthy and impaired individuals. One variable assessed is the external knee adduction moment (EKAM). Variations in EKAM values between investigations may be caused by changes in static standing position, especially foot placement angles which may increase or reduce any differences seen. Purpose of the study The current study aimed to explore the influence of static trial foot position on knee kinematic and kinetic variables during walking. Methods Twelve healthy male participants completed three different static standing trials; 1) 20-degrees toe-in, 2) 0 degree and 3) 20-degrees toe-out before walking at their own pace during a lower limb kinematics and kinetics assessment. First and second peak EKAM was compared between static foot position trials, as well other knee kinematic and kinetic outcomes. Repeated measures ANOVA was used with post hoc pairwise comparison to determine the differences between static foot position trials. Results The first peak of EKAM was significantly smaller in the 20o toe-out angle, than the 20o toe-in angle (p = 0.04 - 8.16% reduction). Furthermore, significant changes were found in peak knee kinematics and kinetics variables (adduction angle, external rotation angle, knee flexion moment external rotation moment, abduction angle and internal rotation angle) in the different positions. Conclusion Modification in static foot position between study visits may result in changes especially in the 1st peak EKAM and other kinematics and kinetics variables during walking. Therefore, standardisation of static foot position should be utilised in longitudinal studies to ensure changes in EKAM are not masked or accentuated between assessments