# Calculation of the Rearfoot Angle Representing Flatfoot from Comparison to the Cavanagh Arch Index
## 3 Results  
### General Statistical Results  
Data from thirty-one flatfoot subjects consisting of 14 males and 17 females presented in Table 1 were statistically analyzed and the result is presented in Table 1. The average age of the participants is 21.3 \(\pm\) 1.5 years. In detail, the average age of males and females is 21.8 \(\pm\) 0.7 years and 20.9 \(\pm\) 1.8 years, respectively. According to WPRO Criteria 2000, someone is categorized as underweight if their BMI \(\leq\) 18.4 kg/m\({}^{2}\), normal if BMI 18.5-22.9 kg/m\({}^{2}\), overweight if BMI 23.0-24.9 kg/m\({}^{2}\), and obese if BMI \(>\) 25.0 kg/m\({}^{2}\)[22]. In this study, 20 subjects (6 males and 14 females) are categorized as having normal BMI; 11 subjects (8 males and 3 females) are categorized as overweight. The range of BMI values of males and females is approximately 20.8-24.5 kg/m\({}^{2}\) for males and 18.8-24.2 kg/m\({}^{2}\) for females, with median values of approximately 23.0 kg/m\({}^{2}\) for males and 21.7 kg/m\({}^{2}\) for females. The mean value of BMI for males is 22.7 \(\pm\) 1.2 kg/m\({}^{2}\), and for females is 21.4 \(\pm\) 1.6 kg/m\({}^{2}\). The mean FL and FW on the soles of the left and right feet of all subjects are almost similar, i.e., 0.1 mm. The range of FL values for males and females is approximately 214.7-264.4 mm and 216.9-252.9 mm, respectively, with FL median values being approximately 245.2 mm for males and 234.3 mm for females. The average FL for males and females is 239.6 \(\pm\) 13.7 mm and 234.4 \(\pm\) 10.9 mm, respectively. In addition, the range of FW values for males and females is approximately 86.3-106.6 mm and 85.5-108.7 mm, respectively, with FW median values being approximately 97.2 mm for males and 94.6 mm for females. The average FW of the males and females is 96.1 \(\pm\) 5.9 mm and 95.2 \(\pm\) 5.9 mm, respectively. The average FAC of all subjects is 11,504 \(\pm\) 1874 mm\({}^{2}\) with median values of approximately 11,016 mm\({}^{2}\). The range of FAC values for males and females is approximately 101,802-16,669 mm\({}^{2}\) and 9084-13,554 mm\({}^{2}\), respectively, with FAC median values being approximately 11647 mm\({}^{2}\) for males and 10,691 mm\({}^{2}\) for females. The average FAC of males and females is 12,373 \(\pm\) 2136 mm\({}^{2}\) and 10,788 \(\pm\) 1293 mm\({}^{2}\), respectively. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Variable**} & \multicolumn{2}{c}{**Left Foot**} & \multicolumn{2}{c}{**Right Foot**} & \multicolumn{2}{c}{**Male**} & \multicolumn{2}{c}{**Female**} & \multicolumn{2}{c}{**All Subjects**} \\ \cline{2-10}  & **Mean \(\pm\) SD** & **Median** & **Mean \(\pm\) SD** & **Median** & **Mean \(\pm\) SD** & **Median** & **Mean \(\pm\) SD** & **Median** \\ \hline Age (year) & & & & 21.8 \(\pm\) 0.7 & 22.0 & 20.9 \(\pm\) 1.8 & 21.0 & 21.3 \(\pm\) 1.5 & 22.0 \\ \hline BMI (kg/m\({}^{2}\)) & & & & 22.7 \(\pm\) 1.2 & 23.0 & 21.4 \(\pm\) 1.6 & 21.7 & 22.0 \(\pm\) 1.5 & 21.8 \\ \hline FL (mm) & 236.7 \(\pm\) 12.3 & 235.3 & 236.8 \(\pm\) 12.6 & 235.4 & 239.6 \(\pm\) 13.7 & 245.2 & 234.4 \(\pm\) 0.9 & 234.3 & 236.8 \(\pm\) 12.3 & 235.3 \\ \hline FW (mm) & 95.7 \(\pm\) 5.9 & 95.2 & 95.6 \(\pm\) 7.1 & 95.2 & 96.1 \(\pm\) 5.9 & 97.2 & 95.2 \(\pm\) 5.9 & 94.6 & 95.6 \(\pm\) 5.8 & 95.2 \\ \hline FAC (mm\({}^{2}\)) & 11,504 \(\pm\) 1874 & 11016 & 11,504 \(\pm\) 1874 & 11,016 & 12,373 \(\pm\) 2136 & 11,647 & 10,788 \(\pm\) 1293 & 10,691 & 11,504 \(\pm\) 1874 & 11,016 \\ \hline AI & 0.35 \(\pm\) 0.04 & 0.36 & 0.35 \(\pm\) 0.06 & 0.36 & 0.33 \(\pm\) 0.05 & 0.32 & 0.37 \(\pm\) 0.04 & 0.38 & 0.35 \(\pm\) 0.05 & 0.35 \\ \hline RFA (\({}^{\circ}\)) & 9.9 \(\pm\) 3.5 & 10.0 & 9.6 \(\pm\) 3.4 & 9.0 & 8.6 \(\pm\) 3.4 & 9.0 & 10.7 \(\pm\) 3.1 & 10.5 & 9.7 \(\pm\) 3.4 & 9.5 \\ \hline \hline \end{tabular}
* FL: foot length, FW: foot width, FAC: foot area contact, RFA: rear foot angle.  
\end{table} 
Table 1: Description of the 31 subjects according to footprint and RFA measurements *.