## 4 Discussion
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline  & & \multicolumn{8}{c}{**Peak Contact Pressure (kPa)**} \\ \cline{2-11}
**Foot Region** & **Plastazote® PE** & **Nora®** & **Lunalastike** & **EVA** & **TPU** & **Firm** & **Void** \\ \cline{2-11}  & **H** & **H-F** & **H** & **H-F** & **H** & **H-F** & **w/o Pad** & **H** & **H-F** & **H** & **H-F** \\ \hline Whole foot & 35.5 & 35.8 & 36.9 & 36.9 & 38.7 & 38.2 & 39.2 & 40.2 & 39.3 & 38.1 & 45.2 \\ Forefoot & 34.1 & 31.8 & 33.9 & 32.9 & 33.6 & 34.0 & 33.5 & 33.7 & 34.9 & 38.1 & 38.6 \\ Medial forefoot & 34.1 & 31.8 & 33.9 & 32.9 & 33.6 & 34.0 & 33.5 & 33.7 & 34.9 & 38.1 & 37.4 \\ Central forefoot & 24.6 & 26.4 & 24.5 & 25.9 & 24.5 & 25.7 & 24.0 & 24.4 & 25.9 & 28.0 & 37.9 \\ Lateral forefoot & 26.1 & 26.8 & 26.0 & 26.2 & 25.8 & 26.3 & 25.7 & 26.2 & 26.6 & 28.2 & 38.6 \\ Midfoot & 34.0 & 32.2 & 33.8 & 32.6 & 33.6 & 33.2 & 33.5 & 33.6 & 33.7 & 37.7 & 45.2 \\ Medial midfoot & 32.2 & 31.8 & 32.0 & 30.7 & 31.0 & 30.4 & 31.5 & 31.8 & 30.6 & 34.7 & 44.6 \\ Lateral midfoot & 34.0 & 32.2 & 33.8 & 32.6 & 33.6 & 33.2 & 33.5 & 33.6 & 33.7 & 37.7 & 45.2 \\ Hindfoot & 35.5 & 35.8 & 36.9 & 36.9 & 38.7 & 38.2 & 39.2 & 40.2 & 39.3 & 36.1 & 37.8 \\ Medial hindfoot & 34.2 & 35.1 & 36.4 & 34.7 & 38.3 & 37.0 & 38.0 & 38.8 & 38.5 & 36.1 & 38.2 \\ Lateral hindfoot & 35.5 & 35.8 & 36.9 & 36.9 & 38.7 & 38.2 & 39.2 & 40.2 & 39.3 & 35.9 & 33.8 \\ \hline \hline \end{tabular} Note: H—heel pad, H—heel–forefoot pad, and w/o—without.  
\end{table} 
Table 2: Regional peak contact pressure of the foot with heel pad and heel–forefoot pad with varying materials. is positioned proximal or distal to the metatarsal heads influences the plantar pressure distribution at the forefoot [25; 47]. Our study also demonstrated that the heel-forefoot pad made from a softer material reduced the medial forefoot peak contact pressure compared with using a heel pad only. However, a heel pad made from softer material reduced the central forefoot peak contact pressure as compared with the heel-forefoot pad and one with voids. A similar plantar pressure reduction was found with low- and medium-density CMIs fabricated from polyurethane and EVA [48]. The FEA technique allows an efficient analysis of the peak contact pressure that is frequently shown in cases of foot complications. The FEA approach highlights some of the important parameters that play an important role, especially in subjects prone to frequent ulceration and re-ulceration. However, frictional stress measurement, which is useful to be evaluated in clinical practice using in-shoe pressure sensors, is rarely reported and remains difficult in actual clinical settings in diabetic foot with neuropathy. Researchers attached sensors to the callus site to determine the forces that trigger callus formation, and it was found that in-shoe shear stresses are a causative factor for foot disorders [49; 50]. The unique aspect of our study was using the FEA to evaluate the frictional stress that occurred with pads fabricated from various materials and those with voids in comparison with insoles without any pads. In our current study, the maximum frictional stress was much higher at the forefoot than at the hindfoot. This higher frictional stress at the forefoot might help in the development of ulceration and re-ulceration [51; 52]. The results of this current study showed, similarly, a trend of maximum frictional stress under the first metatarsal head with pads and without pads compared with at the hindfoot. However, the maximum frictional stress shifted to the midfoot while using a heel-forefoot void. The secondary component causing ulceration can be detected as differences in the peak contact pressure and maximum frictional stress [53]. Recently, many researchers applied artificial intelligence for the purpose of diabetic foot screening and a future advancement [54; 55]. Further improvement can be achieved by combining the FEA approach with artificial intelligence.