Plantar pressure gradient and pressure gradient angle are affected by inner pressure of air insole

Fahni Haris; Yih-Kuen Jan; Ben-Yi Liau; Chang-Wei Hsieh; Wei-Cheng Shen; Chien-Cheng Tai; Yin-Hwa Shih; Chi-Wen Lung

doi:10.3389/fbioe.2024.1353888

Plantar pressure gradient and pressure gradient angle are affected by inner pressure of air insole

Front Bioeng Biotechnol. 2024 Mar 11:12:1353888. doi: 10.3389/fbioe.2024.1353888. eCollection 2024.

Authors

Fahni Haris^{1

2}, Yih-Kuen Jan³, Ben-Yi Liau⁴, Chang-Wei Hsieh⁵, Wei-Cheng Shen⁶, Chien-Cheng Tai⁷, Yin-Hwa Shih¹, Chi-Wen Lung^{3

8}

Affiliations

¹ Department of Healthcare Administration, Asia University, Taichung, Taiwan.
² School of Nursing, Universitas Muhammadiyah Yogyakarta, Yogyakarta, Indonesia.
³ Rehabilitation Engineering Lab, University of Illinois at Urbana-Champaign, Champaign, IL, United States.
⁴ Department of Automatic Control Engineering, Feng Chia University, Taichung, Taiwan.
⁵ Department of Computer Science and Information Engineering, Asia University, Taichung, Taiwan.
⁶ Department of Digital Media Design, Asia University, Taichung, Taiwan.
⁷ International Ph.D. Program for Cell Therapy and Regeneration Medicine, Taipei Medical University, Taipei, Taiwan.
⁸ Department of Creative Product Design, Asia University, Taichung, Taiwan.

Abstract

Clinically, air insoles may be applied to shoes to decrease plantar pressure gradient (PPG) and increase plantar gradient angle (PGA) to reduce foot ulcers. PPG and PGA may cause skin breakdown. The effects of different inner pressures of inflatable air insoles on dynamic PPG and PGA distributions are largely unknown in non-diabetics and people with diabetes. This study aimed to explore the impact of varying inner air insole pressures on PPG and PGA to establish early mitigation strategies for people at risk of foot ulcers. A repeated measures study design, including three air insoles (80 mmHg, 160 mmHg, and 240 mmHg) and two walking durations (10 and 20 min) for a total of six walking protocols, was tested on 13 healthy participants (height, 165.8 ± 8.4 cm; age, 27.0 ± 7.3 years; and weight, 56.0 ± 7.9 kg, BMI: 20.3 ± 1.7 kg/m^2) over three consecutive weeks. PPG, a measurement of the spatial variation in plantar pressure around the peak plantar pressure (PPP) and PGA, a variation in the gradient direction values at the three plantar regions, big toe (T1), first metatarsal head (M1), and second metatarsal head (M2), were calculated. This study indicated that PPG was lower at 80 mmHg air insoles after 20 min of walking in the M1 region (p = 0.010). The PGA in the M2 increased at an air insole of 80 mmHg compared to 240 mmHg (p = 0.015). Compared to 20 min, the 10 min walking duration at 240 mmHg of air insole had the lowest PPG in the M1 (p = 0.015) and M2 (p = 0.034) regions. The 80 mmHg air insole significantly lowered the PPG compared to a 160 mmHg and 240 mmHg air insole. Moreover, the 80 mmHg air insole significantly decreased PPP and increased PGA compared to the 160 mmHg and 240 mmHg air insole. A shorter walking period (10 min) significantly lowered PPG. The findings of this study suggest that people with a higher risk of foot ulcers should wear softer air insoles to have a lower PPG, as well as an increased PGA.

Keywords: big toe; diabetic foot ulcer; metatarsal head; walking duration; walking exercise.

Grants and funding

The author(s) declare that financial support was received for the research, authorship, and/or publication of this article. This study was supported by a grant from the National Science and Technology Council, Taiwan (NSTC 112-2221-E-468-004). The funding agency did not involve data collection, data analysis, and data interpretation.