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

Published online November 20, 2021

https://doi.org/10.12674/ptk.2021.28.4.266

© 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
E-mail: kwonoy@yonsei.ac.kr
https://orcid.org/0000-0002-9699-768X

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 (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

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

Article

Original Article

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

Published online November 20, 2021 https://doi.org/10.12674/ptk.2021.28.4.266

Copyright © 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
E-mail: kwonoy@yonsei.ac.kr
https://orcid.org/0000-0002-9699-768X

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 (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

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

Fig 1.

Figure 1.Measurement of frontal plane projection angle during the single-leg step down using Kinovea® software.
Physical Therapy Korea 2021; 28: 266-272https://doi.org/10.12674/ptk.2021.28.4.266

Fig 2.

Figure 2.Measurement of knee-in distance (KID: distance from great toe to point where line connecting center of patella and anterior superior iliac spine intersects floor, red line) and hip-out distance (HOD: distance from great toe to projection of anterior superior iliac spine on floor, blue line) during the single-leg step down using Kinovea® software. (A) Initial position, (B) KID and HOD without dynamic knee valgus, (C) KID and HOD with excessive dynamic knee valgus.
Physical Therapy Korea 2021; 28: 266-272https://doi.org/10.12674/ptk.2021.28.4.266

Fig 3.

Figure 3.Smartphone placement during the single-leg step down for video recording. A: 15-cm step box height, B: 250 cm from tripod to front of step box, C: 60-cm tripod height.
Physical Therapy Korea 2021; 28: 266-272https://doi.org/10.12674/ptk.2021.28.4.266

Fig 4.

Figure 4.The frontal plane projection angle during the single-leg step down. PFP, pronated foot position.
Physical Therapy Korea 2021; 28: 266-272https://doi.org/10.12674/ptk.2021.28.4.266

Fig 5.

Figure 5.The hip-out distance and knee-in distance during the single-leg step down. PFP, pronated foot position.
Physical Therapy Korea 2021; 28: 266-272https://doi.org/10.12674/ptk.2021.28.4.266

Table 1 . Demographic and general characteristics of the subjects (N = 27).

PFP group (n = 12)Control group (n = 15)p-value
Age (y)25.92 ± 1.7825.60 ± 2.130.684
Height (cm)171.17 ± 7.76172.47 ± 10.050.716
Body mass (kg)72.33 ± 12.2474.60 ± 15.460.682
BMI (kg/m2)24.55 ± 2.7624.82 ± 3.090.815
FPI score7.42 ± 1.682.07 ± 1.75< 0.001

Values are presented as mean ± standard deviation. PFP, pronated foot posture; BMI, body mass index; FPI, foot posture index..