pISSN 2288-6982
eISSN 2288-7105



Original Article

Phys. Ther. Korea 2021; 28(4): 266-272

Published online November 20, 2021

© Korean Research Society of Physical Therapy

Comparison of Dynamic Knee Valgus During Single-leg Step Down Between People With and Without Pronated Foot Using Two-dimensional Video Analysis

Hyun-sook Kim1 , PhD, PT, Hwa-ik Yoo2,3 , BPT, PT, Ui-jae Hwang3,4 , PhD, PT, Oh-yun Kwon3,4 , PhD, PT

1Department of Physical Therapy, Yeoju Institute of Technology, Yeoju, 2Department of Physical Therapy, The Graduate School, Yonsei University, 3Kinetic Ergocise Based on Movement Analysis Laboratory, 4Department of Physical Therapy, College of Health Science, Yonsei University, Wonju, Korea

Correspondence to: Oh-yun Kwon

Received: August 24, 2021; Accepted: August 27, 2021

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.


Background: Considering the kinetic chain of the lower extremity, a pronated foot position (PFP) can affect malalignment of the lower extremity, such as a dynamic knee valgus (DKV). Although the DKV during several single-leg movement tests has been investigated, no studies have compared the differences in DKV during a single-leg step down (SLSD) between subjects with and without PFP.
Objects: The purpose of this study was to compare the DKV during SLSD between subjects with and without PFP.
Methods: Twelve subjects with PFP (9 men, 3 women) and 15 subjects without PFP (12 men, 3 women) participated in this study. To calculate the DKV, frontal plane projection angle (FPPA), knee-in distance (KID), and hip-out distance (HOD) during SLSD were analyzed by two-dimensional video analysis software (Kinovea).
Results: The FPPA was significantly lower in PFP group, compared with control group (166.4° ± 7.5° and 174.5° ± 5.5°, p < 0.05). Also, the KID was significantly greater in PFP group, compared with control group (12.7 ± 3.9 cm and 7.3 ± 2.4 cm, p < 0.05). However, the HOD not significantly differed between two groups (12.7 ± 1.7 cm and 11.4 ± 2.5 cm, p > 0.05).
Conclusion: The PFP is associated with lower FPPA and greater KID. When assess the DKV during SLSD, the PFP should be considered as a crucial factor for occurrence of DKV.

Keywords: Genu valgum, Knee joint, Pes planus