Table 3.

A summary of the studies examined relating to the development of the medial longitudinal arch.

Author	Study Type	Participants & Age Range	Mean Age (±SD)	Method of Analysis	Main Findings
Volpon et al. [29]	Cross-sectional	338 male 334 female 0–15 years	N/A	Footprint contact index II	During the first two years of life, the values for arch height were the largest (indicating a flatter arch). Values decreased rapidly until the age of 6 years, where they slowed until the age of 10.
Bosch et al. [19]	Longitudinal	16 male 20 girls 0–10 years	14.6 ± 1.8 months 122.8 ± 2 months	Arch index	Arch index values decreased by 44% between the ages of 0 and 10 years, indicating the development of the arch. Substantial development of the arch from a flat foot to a regular foot was seen through the ages. By the age of 10, inter-individual differences were equivalent to adults.
Onodera et al. [36]	Cross-sectional	391 male and female 3–10 years	N/A	Arch index Chippaux–Smirak Index Staheli index	The frequency of low arched feet was higher at the age of three compared to other ages. An increase in longitudinal arch development was seen (as measured by all indices). After six years old, arch maturation continued slowly until the age of 10.
Müller et al. [28]	Cross-sectional	3738 male 4050 female 1–13 years	7.2 ± 2.9 years	Arch index	The arch index declined during growth. The mean arch index ranged from 0.3 in infants to 0.2 in 13-year-olds. Between the ages of one and six, a considerable reduction in the arch index was seen; however, from age six, it plateaued. Arch index values were comparable to those of adult’s feet by the age of 6–7.
Mickle et al. [21]	Cross-sectional	36 boys 52 girls 3–5 years	4.2 ± 0.6 years	Arch index	Boys had a higher arch index value than girls (lower arch). Arch index values ranged between 0.01 and 0.36. The flatter feet of boys were thought to be due to a thicker midfoot fat pad. Resolution and development of the arch started earlier in girls.
Pfeiffer et al. [9]	Cross-sectional	424 male 411 female 3–6 years	N/A	Visual inspection Position of the heel	44% of children had a flexible flat foot. The prevalence of flat feet decreased with age; in 3-year-old children, 54% presented with flat feet; 24% of 6-year-olds had flat feet. The prevalence of flat foot was higher in boys (52%) than girls (36%). The prevalence of flat foot continued to decrease from 71% to 32% from 3–6 years.
Forriol et al. [37]	Cross-sectional	663 male 1013 female 3–17 years	N/A	Chippaux–Smirak Index Footprint angle	A high percentage of flat feet was present between 3 and 4 years with the footprint angle (B: 73.5%; G: 68.4–71.9%). Footprint angle increased with age (arch height increased with age) (B 3–4 years: 21.7°; B 15–17 years: 44.6°; G 3–4 years: 26.1°; G 15–17 years: 46.8°). Chippaux–Smirak Index decreased with age (arch height increased with age; B 3–4 years: 50.5%; B 15–17 years: 30.1%; G 3–4 years: 46.9%; G 15–17 years: 27.4%).
Jankowicz-Szymanska et al. [58]	Cross-sectional	710 males 654 female 3–7 years	N/A	Clarke’s angle	Clarke’s angle increased (increase in arch height) with age, apart from in 6-year-old girls. Girls of all ages had higher arches than boys. Clarke’s angle was highest in those with a healthy body weight.
Jankowicz-Szymanska et al. [59]	Longitudinal	102 males 105 females 3–6 years	N/A	Clarke’s angle	A smaller Clarke’s angle (lower arch height) was seen in boys compared to girls. At age six, boys had a lower longitudinal arch than girls (B: 36.63 ± 13.09°; G: 37.31 ± 11.74°).
Ozlem et al. [61]	Cross-sectional	299 male 280 females 6–12 years	9.23 ± 1.66 years	Staheli arch index	The mean arch index for all children was 0.74 ± 0.25. The mean arch index of group 1 (normal to mild flatfoot) was 0.67 ± 0.19. The mean arch index of group 2 (moderate to severe flatfoot) was 1.12 ± 0.17. A negative correlation between the arch index and age (increase in arch height with age).
Waseda et al. [20]	Cross-sectional	5311 male 4844 female 6–18 years	N/A	Arch height ratio	There was no gender difference in arch height ratio. In boys, the arch height ratio was relatively flat until 11 years old but increased quickly between age 11–13 (B 11 years: 14.1 ± 2.6%; B 13 years: 15.4 ± 2.6%). In girls, the arch height ratio was flat until 10 years old but significantly rose between 10–12 years old (G 10 years: 13.6 ± 2.5%; G 12 years: 14.8 ± 2.6%). A plateau in girls was seen around the age of 17 (16.5 ± 2.3%) and in boys at age 18 (16.9 ± 2.4%).
Stavlas et al. [74]	Cross-sectional	2935 male 2931 6–17 years	N/A	Footprint angle Arch index Chippaux–Smirak Index	Boys had higher rates of low arched feet compared to girls (B 6 years: 9% low/flat arch; G 6 years: 7.2% low/flat arch). The frequency of high arched and low arched feet present in the youngest age group decreased with age (B 6 years 9% low/flat arch; B 17 years: 0.6% low/flat arch; G 6 years: 7.2% low/flat arch; G 17 years: 1.6% low/flat arch).
Morita et al. [62]	Cross-sectional	146 male 155 female 8–11 years	8.6 ± 0.5 years 10.6 ± 0.5 years	Arch height ratio	Arch height was greater in older girls than in boys of the same age (B: 13.7 ± 2.3; G: 14.7 ± 2.4).
Nikolaidou et al. [56]	Cross-sectional	67 male 65 female 9–11 years	10.4 ± 0.9 years	Chippaux–Smirak Index Arch index	Arch index measurements showed that 30% of participants presented with a low foot type. Chippaux–Smirak Index measurements showed that 46% of participants presented with a low or flat foot type.
Staheli et al. [69]	Cross-sectional	441 male and female 1–80 years	N/A	Staheli index	During infancy, typical values ranged between 0.7 and 1.35. A sizeable normal range from about 0.3–1 is seen after the middle of childhood and through to adulthood.
Bosch et al. [66]	Cross-sectional	104 male and female 1–70 years	1.3 ± 0.4 years 7 ± 0.4 years	Arch index	The largest arch index values were found in the toddler group (0.36), which described a flat arch. The 7-year-old group had an arch index of 0.18. Adults presented with a mean arch index of 0.19 and seniors 0.21.

Abbreviations: B—Boys; G—Girls; N/A—Not Available.