J Korean Foot Ankle Soc.  2022 Sep;26(3):130-135. 10.14193/jkfas.2022.26.3.130.

Assessment of Validity and Reliability of Plantar Pressure in Smart Insole

• Kang HW
• An YL
• Kim DY
• Lee DO
• Park GY
• Lee DY

• KMID: 2533195
• DOI: http://doi.org/10.14193/jkfas.2022.26.3.130

Abstract

Purpose
Smart insoles are wearable devices that are inserted into shoes. Smart insoles with built-in pressure and acceleration sensors can measure the plantar pressure, stride length, and walking speed. This study evaluated the validity and reliability of the plantar pressure measurements of smart insoles during walking on flat ground.
Materials and Methods
Twenty one subjects were included in this study. After wearing smart insoles, I-SOL^® (Gilon, Seongnam, Korea), the subjects walked a 10 m corridor six times at a rate of 100 steps/min, and the middle three steps, free from direction changes, were chosen for data analysis. The same protocol was repeated after wearing Pedar-X (Novel Corporation, Munich, Germany), an insoletype plantar pressure measurement equipment with proven validity. The average maximum pressure (P_peak , kPa) and the time at which P_peak appeared (P_time , %stride) were calculated for each device. The validity of smart insoles was evaluated by using the interclass correlation coefficient (ICC) of P_peak and P_time between the two instruments, and Cronbach’s alpha was obtained from the P_peak values to evaluate the reliability.
Results
The ICC of P_peak was 0.651 (good) in the hallux, 0.744 (good) in the medial forefoot, 0.839 (excellent) in the lateral forefoot, and 0.854 (excellent) in the hindfoot. The ICC of P_time showed 0.868 (excellent) in the hallux, 0.892 (excellent) in the medial forefoot, 0.721 (good) in the lateral forefoot, and 0.832 (excellent) in the hindfoot. All ICC values showed good or excellent results. The Cronbach’s alpha of P_peak measured in the smart insoles was 0.990 in the hallux, 0.961 in the medial forefoot, 0.973 in the lateral forefoot, and 0.995 in the hindfoot; all indicated excellent reliability in all areas.
Conclusion
The plantar pressure measurements of smart insoles during walking on a flat ground showed validity compared to Pedar-X, and high reliability after repeated measurements.

Keyword

Foot; Plantar pressure; Smart insole; Validity; Reliability

Figure

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  Figure 1 (A) Smart insoles, I-SOL® (Gilon, Seongnam, Korea). (B) Composition of smart insole. (C) In-shoe plantar pressure measurement system, Pedar-X (Novel, Munich, Germany; www.novel.de). FSR: force-sensitive resistor.

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  Figure 2 A participant wearing smart insoles (A) and Pedar-X (B) inside running shoes (New Balance, Boston, MA, USA).

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  Figure 3 (A) Position of force-sensitive resistor (FSR) in smart insole (circles). (B) Corresponding positions of FSRs in Pedar-X. (C) The sensors used in Pedar-X (① hallux, ② medial forefoot, ③ lateral forefoot, ④ heel).

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  Figure 4 The device for calibration of smart insoles.

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  Figure 5 Peak pressure curves of a participant wearing smart insoles (A) and Pedar-X (B).

Reference

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