Analysis of 6−10-Year-Old Children Feet Anthropometric Sizes and Pes Planus, Pes Cavus Predisposition in Central Anatolia

Background: Information on the foot structures of Central Anatolian children is limited. Foot structures of children aged 6−10 years were shown to be different according to sex and increasing age. Objective: This study aimed to compare the foot anthropometric values by age and sex and collect the foot anthropometric data to reveal the relationship between pes planus and pes cavus in the arches of children according to age. Methods: Footprints of 335 children (180 boys and 155 girls) aged 6−10 years were taken by the footprint method and evaluated using 18 different parameters. To examine the relationship between the parameters, normality values were examined. Independent samples t-test was used to analyze sex differences in terms of foot size and shape. Results: Correlations between other parameters were determined using the correlations analysis method. TFL (Truncated foot length), metatarsal circumference, and foot length were strongly correlated with age in the children. Foot rotation increased with body mass index in the girls compared to that in the boys. Conclusions: Planning shoe production accordingly will contribute to the development of healthy feet in children. This article focused on foot structures of in Central Anatolia and to identify early foot deformities in children. This study found that the length of the TFL was smaller in boys than in girls.


Introduction
When designing shoes for any age group, anthropometric data of that group is of great importance. The use of correct foot sizes improves one's foot health and comfort. Shoes that do not t the foot structure used at a young age can lead to permanent foot deformities. However, foot deformities that can be noticed at a young age can be eliminated before reaching the developmental period. Foot measurements can be taken by different methods. These are measuring with a caliper or tape measure, threedimensional scanning, photographing, or foot-printing [1].
When studies on a similar subject are examined, foot morphologies may vary between sexes and different populations. As a result, the data obtained in this study vary according to age and sex [2][3][4]. Using these data, designing shoes, which is unique to foot morphology, can be bene cial for children's foot health.
Previous studies have determined the morphological dimensions of feet according to age groups in different nations. In Turkey, there are studies from anthropological studies such as sex prediction made from adult foot structure when examined. In this study, we aimed to determine the foot dimensions of the 6 − 10-year-old children in Central Anatolia and to identify early foot deformities in children.

Materials And Methods
This study included a sample group of 335 children (155 girls, 180 boys) aged between 6 and 10 years.
The sample group consisted of children living in Central Anatolia, without any walking disorder and foot pathology. Approval was obtained from the ethical board committee of Ankara University, and informed consents were obtained from the families of the children included in the sampling before initiation of the study. Data were collected from 24 different measurements including the shoe size of the dominant foot, metatarsal circumference, TFL, and Staheli arch index. In addition, demographic data such as height, body weight, and body mass index of children were measured ( Table 1). The shoe types and sizes used by the children in the sample were subsequently determined. To determine the anthropometric dimensions of the foot, footprints were taken from the foot of the individuals using the foot-print method ( Fig. 1.). The knee was exed while the footprint was taken. The TFL, FL, X, Y, S, Arch Index (B / A + b + C), Chippaux Smirak Index (B / A * 100%), Staheli Arc, and foot rotation values of the children were examined ( Table 2). In addition, metatarsal circumference and oblique measurements were taken directly from the feet of children (Table 3).  Statistical Analysis Data were analyzed using the Statistical Package for Social Sciences (SPSS), version 23.0. When comparing the parameters, the normality values were rst examined. Then, the independent samples ttest was used to analyze sex differences in terms of foot size and shape. To understand the relationship between other parameters, correlations analysis was performed.

Results
The participants of the study consisted of 335 children (155 girls and 180 boys) aged between 6 and 10 Further, the correlation (0.177) between body mass index and foot rotation was found to be very weak.
When the correlation results of S value were analyzed, a weak correlation was observed between the S, Navicular ground distance, and 1st Metatarsal ground distance. Additionally, a weak correlation (-0.369) was found between the Chippaux Smirak index and Navicula to ground distance.
When the correlation analysis with other values of the Staheli Arc Index was examined, a weak correlation between the LLA angle and Navicula ground distance was observed. There were also weak correlations between the LLA angle, body mass index, foot rotation, and calcaneus angle.
A relationship was found between the metatarsal circumference and sex, which was stronger in the boys than in the girls (P = 0.18). No signi cant differences were observed between the sexes in terms of the 1st metatarsal to ground distance, TFL (P = 0.227), and foot length; however, there was a statistically signi cant difference in foot rotation between the sexes (P = 0.034), with girls having smaller foot rotation than boys.  According to the data determined in the classi cation made via the Staheli arch index, pes cavus is more common in girls than in boys. However, pes planus is more common in boys than in girls. Based on the Staheli arc index, almost the same number of girls and boys had a normal arc structure.

Discussion
This study evaluated the foot measurements of children living in Central Anatolia using different methods. The rate of increase in foot sizes of girls and boys aged between 6 and 10 years varied. When the measurements of boys and girls of the same age were examined, it was found that the length of the TFL was smaller in boys than in girls.

The relationship between foot length and other parameters of children
Foot length was strongly correlated with age (r = 0.736 for girls; r = 0.725 for boys). Foot length and height were strong correlated (r = 0.906 for girls; r = 0.887 for boys). Body weight and foot length of children were strongly correlated (r = 0.822 for girls; r = 0.836 for boys). There was a strong correlation between the metatarsal circumference measurements and foot length (r = 0.756 for girls; r = 0.817 for boys). The relationships between the oblique measure and foot height of children (r = 0.837 for girls; r = 0.858 for boys) and between the calculated arch index and foot length (r = 0.946 for girls; r = 0.946 for boys) were strong. It was determined that the foot height had a moderate relationship with the X angle (r = 0.695 for girls; r = 0.625 for boys). The distance of the medial malleolus to the ground was moderately related to the height of the foot (r = 0.526 for girls; r = 0.546 for boys).

Comparison of FL with other nations
In this study, FL values of Turkish children at different ages were examined. In this context, these were evaluated in different countries. Xu's study also used data from Chinese children [5]. Delgado's study included data of Spanish children [6]. Barisch's [7] study included data of German children and Waseda's [8] study included data from Japanese children. Data of Mexican children were included in Prado-Leon's study [9]. In these studies, the age ranged from 6 to 12 years. In addition to the comparison, Bari's study included boys aged 5 and 6 years [10]. The data are given in Fig. 5.
The height of the navicular can be de ned as the distance from the base of the medial projection of the navicular tuberosity to the ground. When the relationship between navicular height and age was examined, a low correlation was observed (r = 0.344 for girls; r = 0.354 for boys). Figure 6 shows the comparison of Turkish children with navicular height and Waseda's (2014) study with Japanese children [8].
The arc index value of Turkish children was also calculated and compared with that of children from other countries. In this context, the arch index values of German children were taken from Müller's study [11]. The arch index values of children living in two different countries are given in Fig. 7.
The Chippaux Smirak index of Turkish children was examined by age [12]. Comparison of children with those from other nations has been made. Sacco's [13] study obtained the values of Brazilian and German children. A comparison of Echarri's [1] study with children in Congolese with Turkish children was made. The Chippaux Smirak indexes of children from four different countries are given in Fig. 8.
The Staheli Arc values of children were examined according to age [14]. However, the Staheli Arc values of Turkish children were compared with those of Brazilian, German, and Congolese children. Comparison of Staheli Arc values is given in Fig. 9.

Conclusion
This study aimed to determine the foot sizes and foot structures of children living in Central Anatolia. The results of the study may be used as an important resource for shoe designers in terms of child foot health. Foot structures of children aged 6 − 10 years were shown to be different according to sex and increasing age. The data of the study varies according to the number of individuals participating in the sampling and the techniques used to measure the foot structure; therefore, increasing the sample size and the use of three-dimensional scanning system to analyze Turkey's different regions of the foot and arch structure is proposed. Declarations