Identification of characteristics of foot position and angle during swing phase in fallers using principal component analysis

Takuma Inai; Yoshiyuki Kobayashi; Chenhui Huang; Koji Fujita; Masahiro Fujimoto; Fumiyuki Nihey; Akiko Yamamoto; Kanako Nakajima; Kentaro Nakahara; Gaku Kutsuzawa; Kenichiro Fukushi; Shoma Kudo

doi:10.3389/fbioe.2023.1117884

Identification of characteristics of foot position and angle during swing phase in fallers using principal component analysis

Front Bioeng Biotechnol. 2023 Feb 14:11:1117884. doi: 10.3389/fbioe.2023.1117884. eCollection 2023.

Affiliations

¹ QOL and Materials Research Group, National Institute of Advanced Industrial Science and Technology, Tokyo, Japan.
² Exercise Motivation and Physical Function Augmentation Research Team, National Institute of Advanced Industrial Science and Technology, Tokyo, Japan.
³ Biometrics Research Labs, NEC Corporation, Tokyo, Japan.
⁴ Department of Functional Joint Anatomy, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
⁵ Department of Orthopaedic and Spinal Surgery, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.

Abstract

Identifying the characteristics of fallers is important for preventing falls because such events may reduce quality of life. It has been reported that several variables related to foot positions and angles during gait (e.g., sagittal foot angle and minimum toe clearance) differ between fallers and non-fallers. However, examining such representative discrete variables may not be sufficient to detect crucial information, which may be contained in the large portions of unanalyzed data. Therefore, we aimed to identify the comprehensive characteristics of foot position and angle during the swing phase of gait in non-fallers and fallers using principal component analysis (PCA). Thirty non-fallers and 30 fallers were recruited for this study. We performed PCA to reduce the dimensions of foot positions and angles during the swing phase and obtained principal component scores (PCSs) for each principal component vector (PCV), which were then compared between groups. The results revealed that the PCS of PCV3 in fallers was significantly larger than that in non-fallers (p = 0.003, Cohen's d = 0.80). We reconstructed waveforms of foot positions and angles during the swing phase using PCV3 and our main findings can be summarized as follows. Compared to non-fallers, fallers have a 1) low average foot position in the z-axis (i.e., height) during the initial swing phase 2) small average foot angle in the x-axis (i.e., rotation in the sagittal plane), during the initial swing phase, and 3) large variability in foot position in the y-axis (i.e., anterior/posterior position) during the initial swing phase. We can conclude that these are characteristics of gait related to fallers. Therefore, our findings may be beneficial for evaluating fall risk during gait using a device such as a shoe- or insole-embedded inertial measurement unit.

Keywords: fallers; foot; gait; position; principal component analysis; swing phase.