Development and evaluation of a system to assess the effect of footwear on the in shoe plantar pressure and shear during gait

In this paper, we propose a system to assess the effect of footwear on the in-shoe plantar pressure and shear during gait. In our previous study, we developed a system for measuring the plantar pressure and shear inside footwear using specialized shoes and insoles with sensors. In this study, based on the previous study, 1) we realized a method to measure directly the in-shoe plantar pressure and shear applied from footwear, 2) verified the validity and reliability of the method and 3) evaluated the ability of the system to assess the effect of footwear by measurements with multiple subjects and various footwear. The reliability and validity were demonstrated by comparison with our previous system. From the evaluation of the newly developed system, we found four suggestions as the following; a) Footwear does not always reduce the pressure and shear force. b) Fixing the instep with shoelace or straps is effective in the reduction of shear force on risk regions of plantar. c) People with callus show significantly higher peak shear force (3.31 ± 0.78 (kgf)) than people without callus (2.03 ± 0.42 (kgf)) when they walk with their usual wearing shoes (p < 0.01). But in barefoot walking, there is no significant difference (2.59 ± 1.08 (kgf) versus 2.67 ± 0.99 (kgf), (p = 0.66)). d) People with callus can reduce the shear force by changing footwear. The system employed in this study can be used for assessing the effect of the intervention such as footwear or instruction of a walk.