The human foot is a crucial component of the musculoskeletal system, uniquely shaped for each individual [1]. The foot comprises 26 bones, 33 joints, various muscles, tendons, and ligaments, evolving in shape and proportion during growth to adapt to its functions [2]. This growth, a multifactorial process, is influenced by intrinsic factors such as age, sex, ethnicity, puberty, and nutritional status and extrinsic factors such as footwear [3–5]. In Chinese school children, girls have smaller feet than boys [6]. The most significant foot growth rates were observed at 7–9 years of age for girls and 8–9 and 10–11 years for boys. During these ages, children are highly active, engaging in various activities, which contributes to their rapid foot growth. Foot dimensions differ between boys and girls around the age of 8 years [7,8].

The primary function of footwear is to protect the feet. However, with the increase in fashionable children's footwear, school administrators and parents/guardians often prioritize aesthetic appeal over the proper development of a child's feet. This trend increases the likelihood of locomotory difficulties for the child. While 96–99% of children are born with healthy feet, 40% develop foot-related challenges in adulthood, often owing to wearing inadequately fitted shoes [9]. Footwear, a major extrinsic factor, significantly affects the gait pattern of children [4], acting as an interface between the foot and the ground.

Walking in shoes increases parameters such as velocity, step length, step time, the base of support, double-support time, stance time, time to toe-off, and range of motion (ROM) [10]. Conversely, walking in shoes decreases cadence, single-support time, ankle max-dorsiflexion, ankle at foot-lift, hallux ROM, arch length change, foot torsion, forefoot supination, forefoot width, and mid foot ROM across all planes [10]. Additionally, running in shoes reduces long-axis maximum tibial acceleration, shock-wave transmission as a ratio of maximum tibial acceleration, ankle plantar flexion at foot strike, knee angular velocity, and tibial swing velocity [11]. Children’s footwear should be designed well and fit properly to support efficient ambulation and proper biomechanical processes during their growth and development [12]. Proper footwear can help prevent the development of foot-related issues that arise from poorly fitted shoes.

During early school years, children's feet grow, on average, by 1 cm per year [2,13]. For children <15 years old, the recommended extra space at the front of the shoes is approximately 10 mm, which is the difference between the length of the foot and inner length of the footwear [14]. Acceptable values of functional length excess are 8–12 mm, considering a measurement error of ±2 mm. Footwear is considered too short if the extra space is <8mm, appropriate if it falls within 8–12 mm, and too long if it is >12 mm [14]. For width, the criteria are as follows: too narrow if the extra space is <1 mm, appropriate if it is between 1–3 mm, and too wide if it is >3 mm [14,15].

Foot ailments like hallux valgus, Achilles tendonitis, athlete's foot, corns, and calluses in school children are often due to ill-fitting footwear [16]. Ill-fitting shoes can cause postural imbalance, discomfort, and coordination impairment [17]. In Nigeria, studies mainly covered flatfoot prevalence, age, and footwear types [18] but did not explore the relationship between footwear fitting and foot shape. This study aimed to investigate the relationship between footwear fitting and foot shape among primary school children.

Research Design and Study Population

This study used an ex post facto research design and recruited 53 primary school children in Umuchiana village Southeastern Nigeria. The primary schools involved were First Hill, All Saints, African Pride, and Efosie.

Eligibility

This study included 8-year-olds who could understand and follow instructions, wore footwear at school, and had obtained informed consent from their parents or guardians. Children who were underweight or overweight, declined to participate, or had difficulty understanding and following instructions were excluded. Additionally, individuals with absent feet, a history of foot surgery or trauma, or underlying medical conditions that could impact foot shape or size were also excluded. Furthermore, participants who wore orthotics or specialized footwear that could influence foot shape or size were excluded.

Data Collection

Ethical approval was obtained from the Ethics Committee of Nnamdi Azikiwe University Teaching Hospital, Nnewi. Height was measured using a tape measure. Body weight was measured using a mechanical weighing scale. Footwear measurements were taken using a tape measure, where the length and width of each piece of footwear were recorded.

To evaluate the structure of the foot, we measured the plantar foot surfaces of the participants while they stood in a relaxed stance. We used ink and A4 paper for this purpose. Firstly, the participants' feet were cleaned and then dipped in ink. After that, they were pressed onto separate sheets of A4 paper to obtain clear footprints. From these footprints, we measured and calculated several key indices:

Foot Length: The distance from the farthest point of the forefoot to the farthest point within the hind foot.

Foot Width: The distance between the most centrally located point on the head of the first metatarsal bone and the most laterally located point on the head of the fifth metatarsal bone.

Clarke’s Angle: The longitudinal foot arch and was measured by drawing a tangent to the medial edge of the foot and the line connecting the point of the largest recess of the footprint with the first metatarsal point.

Wejsflog Index: This characterizes the transverse foot arch and was calculated as the foot length ratio to foot width derived from measurements in meters.

Hallux Valgus Angle: This denotes the angle between the tangent line to the medial edge of the foot and the tangent to the pad of the big toe from the first metatarsal.

Angle of The Varus Deformity of the Fifth Toe: This indicates the angle between the tangent line to the lateral edge of the foot and the tangent to the pad of the fifth toe from the fifth metatarsal.

Statistical Analysis

Data were analyzed using SPSS version 26. Descriptive statistics were used to present the results. Sex differences were analyzed using the Mann–Whitney U test. To compare the results from the right and left feet, we used the Wilcoxon signed-rank test. The influence of independent variables (functional length and width excess of footwear) on dependent variables (foot shape) was evaluated through multiple regression analysis and simple regression. Statistical significance was set at P<0.05.

This study included 53 participants, with an almost equal distribution between the sexes: 26 males (49.1%) and 27 females (50.9%). The mean height, weight, and body mass index were 1.31 m, 26.17 kg, and 15.16 kg/m2 (Table 1).

Table 1: Socio-demographic characteristics of the participants.

FHNPS, First Hill Nursery and Primary School; ASNPS, All Saints' Nursery and Primary School; APNPS, African Pride Nursery and Primary School; ENPS, Efosie Nursery and Primary School.

Table 2 shows the significant differences in foot and footwear parameters between males and females. Specifically, the left and right foot widths showed significant differences. Males had higher mean ranks for the left and right foot widths than females, with mean ranks of 32.83 for males and 21.39 for females (U = 199.50, p = 0.01). Additionally, the Wejsflog index was significantly different between the sexes. The left Wejsflog index had a mean rank of 19.98 for males and 33.76 for females (U = 168.50, p = 0.00). Similarly, the right Wejsflog index showed a mean rank of 19.85 for males and 33.89 for females (U = 165.00, p = 0.00). The right hallux valgus angle also differed significantly, with males having a mean rank of 31.37 and females 22.80 (U = 237.50, p = 0.04). The left Clarke’s angle was significantly different, with males at a mean rank of 21.52 and females at 32.28 (U = 208.50, p = 0.01).

Table 2: Sex differences in the foot and footwear parameters.

Functional width excess revealed significant sex differences. The left functional width excess had mean ranks of 21.48 for males and 32.31 for females (U = 207.50, p = 0.01), while the right functional width excess showed mean ranks of 22.54 for males and 31.30 for females (U = 235.00, p = 0.04).

Table 3 compares the right and left foot and footwear parameters. The mean rank for the left foot width was 24.83 and 25.43 for the right foot width, with a test statistic (W) of -2.576 and p-value of 0.01. This indicates a significant difference in foot width between the two sides. A significant difference was observed in functional length excess between the left and right sides. The left side had a mean rank of 18.47, and the right had a mean rank of 27.75, with a test statistic (W) of -2.263 and p-value of 0.02.

Table 3: Wilcoxon signed rank test comparing the right and left foot and footwear parameters.

Significant correlations were observed between foot parameters and functional length and width excess (Table 4). The analysis of foot parameters revealed significant relationships between foot width, the Wejsflog index, and functional width excess. For the left foot, a significant negative correlation was observed between foot width and left functional width excess (Rho = -0.418, P = 0.002). This implies that as the left foot width increases, the left functional width excess decreases. Similarly, the right foot exhibited significant negative correlations with left and right functional width excess. The right foot width was negatively correlated with left functional width excess (Rho = -0.344, p = 0.012) and right functional width excess (Rho = -0.402, p = 0.003), indicating that greater right foot width corresponds to reduced functional width excess on both sides.

Table 4: Spearman rank test showing the relationship between functional length and width excess of footwear and each foot shape parameter.

LFLE, Left Functional Length Excess; RFLE, Right Functional Length Excess; LFWE, Left Functional Width Excess; RFWE, Right Functional Width Excess

Regarding the Wejsflog index, significant positive correlations were observed with functional width excess. For the left foot, a significant positive correlation was observed between the Wejsflog index and left functional width excess (Rho = 0.672, p = 0.000), suggesting that higher Wejsflog index values are associated with greater left functional width excess. Additionally, the Wejsflog index of the left foot was positively correlated with right functional width excess (Rho = 0.494, p = 0.000), indicating that higher values on the left foot are linked to increased right functional width excess. For the right foot, the Wejsflog index showed significant positive correlations with left and right functional width excess. The Wejsflog index was positively correlated with left (Rho = 0.510, p = 0.000) and right functional width excess (Rho = 0.636, p = 0.000), indicating that higher Wejsflog Index values on the right foot correspond to greater functional width excess on both sides. These findings highlight the intricate relationships between foot dimensions and footwear fitting parameters, emphasizing the importance of considering these factors for proper footwear design and fitting.

Table 5: Shows significant indicators that functional width excess predicts left and right foot width and Wejsflog index.

Proper footwear fitting is crucial for the overall foot health and development of children. In primary school children, ill-fitting shoes can lead to various foot deformities and discomforts, affecting their mobility and quality of life. This study investigated the relationship between footwear fitting and foot shape among primary school children in Umuchiana Anambra State, Nigeria. By understanding these relationships, we aimed to provide Insights into better footwear design and selection, ensuring healthier foot development for children.

In this study, males had wider left and right foot widths and right hallux valgus angle deformity. This is similar to previous findings and may have further buttressed that females’ feet are smaller, narrower, and slender while males’ feet are wider and voluminous [19,21]. Considering the differences between male and female foot shapes in this study, differences were observed in footwear sizes. This may explain why males and females do not wear the same footwear. Also, the broader foot widths in males can be attributed to several factors, including genetic predispositions and differences in physical activity levels. Males often engage in more vigorous physical activities, such as running and jumping, which can contribute to developing wider feet [20]. These activities place greater biomechanical demands on the feet, potentially leading to structural adaptations over time. Moreover, hormonal differences between males and females can influence bone growth and development, resulting in variations in foot width [22].

The presence of a significant right hallux valgus angle deformity among the males is noteworthy. Hallux valgus, commonly known as a bunion, is characterized by a lateral deviation of the big toe [23], which can be painful and lead to further complications if left untreated [24]. The higher prevalence of this deformity in males could be linked to several factors. One possible explanation is the type of footwear commonly worn by boys in this region. If the shoes are too tight or improperly fitted, they can exert pressure on the toes, leading to deformities such as hallux valgus [16]. Furthermore, genetic factors may play a role, as certain foot shapes that are predisposed to hallux valgus can be inherited [21].

This study revealed that the left foot width was not symmetrical with the right foot width. This asymmetry in foot width can be attributed to several factors, including genetic predispositions and differences in biomechanical forces. Genetics significantly influence foot morphology, leading to variations in bone structure and growth patterns that can cause asymmetries in foot width. Children's bones may grow at different rates on each side, contributing to these differences [25]. Moreover, daily activities create unique stress and pressure distributions on each foot based on gait, weight distribution, and posture [26,27]. This can result in structural adaptations and variations in foot width, especially if one foot is used more frequently in activities such as kicking or running [8].

In this study, excess footwear length does not significantly alter foot shape, which contrasts with findings from a previous study [1]. However, our study revealed that functional length excess significantly affects Clarke’s angle of the right and left foot and the Wejsflog index of the right foot. These discrepancies could be attributed to differences in the age of the participants studied. A higher incidence of pes planus was observed in children who began wearing footwear early in life [18]. Our study focused on 8-year-olds, whereas earlier studies involved 7-year-olds. Regarding footwear width excess, our findings support those of a study [17], indicating that it predicts foot width and the Wejsflog index. Specifically, our study shows that an increase in left functional width excess correlates with an average increase of 0.440 in left foot width and 0.658 in the left Wejsflog index.

Similarly, a unit increase in right functional width excess corresponds to an average increase of 0.379 in right foot width and 0.625 in the right Wejsflog index. These findings suggest that participants wearing footwear with greater width excess have wider feet, while those with lesser width excess have narrower feet. These conclusions are consistent with a previous study [8], which reported that excessive width allowance in footwear can negatively impact gait patterns in children.

This study had some limitations. First, this study was confined to a few primary schools in Anambra State. This restriction limits the generalizability of the findings to other regions within Nigeria and potentially overlooks regional variations in foot morphology and footwear practices. Moreover, this study’s design captures only a point in time and does not allow for the observation of changes or trends over time. Furthermore, this study did not track changes in foot shape and footwear fitting over an extended period. Longitudinal studies are necessary to observe how these variables change as children develop and to provide a more comprehensive understanding of the relationship between foot shape and footwear fitting.

Sex differences significantly influence the left and right foot width, left and right Wejsflog index, right hallux valgus angle, and left Clarke’s angle. Males exhibited wider left and right foot widths, while females had higher left Clarke’s angle (indicating differences in longitudinal foot arch). Footwear length fitting (excess) did not significantly affect the participants' foot shapes. However, functional width predicts foot width and the Wejsflog index, highlighting that footwear width fitting (excess) significantly impacts foot shape.

We thank the primary school children, parents, and teachers who participated in this study. We also thank the heads of the schools and staff for their support and cooperation.

Spearman rank order correlation was used to determine the correlation between cardiovascular risk, stress level, and QoL. Statistical significance was set at P<0.05.

1. Puszczalowska Lizis E, Lukasiewicz A, Lizis S, Omorczyk J. The impact of functional excess of footwear on the foot shape of 7-year-old girls and boys. PeerJ. 2021; 9: e11277.
2. Vrdoljak O, Kujundzic Tiljak M, Cimic M. Anthropometric measurements of foot length and shape in children 2 to 7 years of age. Period Biol. 2017; 119: 125-129.
3. de Onis M. Update on the implementation of the WHO child growth standards. Nutr Growth. 2013; 106: 75-82.
4. Hill M, Healy A, Chockalingam N. Key concepts in children’s footwear research: a scoping review focusing on therapeutic footwear. J Foot Ankle Res. 2019; 12: 1-3.
5. Gonzalez Elena ML, Fernandez Espejo E, Castro Mendez A, Guerra Martin MD, Cordoba Fernandez A. A cross-sectional study of foot growth and its correlation with anthropometric parameters in a representative cohort of schoolchildren from Southern Spain. Int J Environ Res Public Health. 2021; 18: 4031.
6. Xu M, Hong Y, Li JX, Wang L. Foot Morphology in Chinese School Children Varies by Sex and Age. Med Sci Monit. 2018; 24: 4536-4546.
7. Delgado Abellan L, Aguado X, Jimenez Ormeno E, Mecerreyes L, Alegre LM. Foot morphology in Spanish school children according to sex and age. Ergon. 2014; 57: 787-797.
8. Zhang XL, Zhu XL. Biomechanical features of children's foot and design of children's shoes. J Beijing Sport Univ. 2010; 33: 57-61.
9. Kinz W, Groll Knapp E, Klein C. Children wearing shoes of insufficient length. Pädiatrie & Padologie. 2015; 50:106-109.
10. Wegener C, Hunt AE, Vanwanseele B, Burns J, Smith RM. Effect of children's shoes on gait: a systematic review and meta?analysis. J Foot Ankle Res. 2011; 4.
11. Cigoja S, Fletcher JR, Esposito M, Stefanyshyn DJ, Nigg BM. Increasing the midsole bending stiffness of shoes alters gastrocnemius medialis muscle function during running. Sci Rep. 2021; 11: 749.
12. Rajchel Chyla B, Skrzynska B, Janocha M, Gajewski R. The foot length changes due to age as well as load during ambulation and determination of the toe allowance. Przegl?d Wlokienniczy. 2012; 3: 23-26.
13. Chen C, Milbrandt TA, Babadi E, et al. Normative femoral and tibial lengths in a modern population of twenty-first-Century U.S. Children. J Bone Joint Surg Am. 2023; 105: 468-478.
14. Knapik H, Pawlowa M. The problem of the fitting of footwear used and purchased for children and youth in Poland. Design, materials, leather, clothing and footwear technology. Radom: University of Technology. 2000; 156-165.
15. Hettigama IS, Punchihewa HK, Heenkenda NK. Ergonomic footwear for Sri Lankan primary schoolchildren: A review of the literature. Work. 2016; 55: 285-295.
16. Buldt AK, Menz HB. Incorrectly fitted footwear, foot pain and foot disorders: A systematic search and narrative review of the literature. J Foot Ankle Res. 2018; 11: 43.
17. Puszczalowska Lizis E, Zarzyczna P, Mikulakova W, Migala M, Jandzis S. Influence of footwear fitting on feet morphology in 9 year old girls. BMC Pediatr. 2020; 20: 349.
18. Ibikunle PO. Prevalence of pes planus and its associated factors among primary school pupils aged 8-12 years in southeast Nigeria. Niger Journal Med Rehab. 2017; 19.
19. Frey C. Foot health and shoewear for women. Clin Orthop Relat Res. 2000; 372: 32-44.
20. Puszczalowska Lizis E, Lizis S. Foot Structure of Girls and boys in the final stage of early childhood taking into account the half-yearly age ranges. Int J Environ Res Public Health. 2022; 20: 629.
21. Zhao X, Tsujimoto T, Kim B, Katayama Y, Tanaka K. Characteristics of foot morphology and their relationship to gender, age, body mass index and bilateral asymmetry in Japanese adults. J Back Musculoskelet Rehabil. 2017; 30: 527-535.
22. Balzer BWR, Cheng HL, Garden F, Luscombe GM, Paxton KT, Hawke CI, et al. Foot length growth as a novel marker of early puberty. Clin Pediatr (Phila). 2019; 58: 1429-1435.
23. Shi GG, Whalen JL, Turner III NS, Kitaoka HB. Operative approach to adult hallux valgus deformity: principles and techniques. J Am Acad Orthop Surg. 2020; 28: 410-418.
24. Monteagudo de la Rosa M, Martinez de Albornoz P. Management of complications after hallux valgus reconstruction. Foot Ankle Clinics. 2020; 25: 151-167.
25. Lui JC, Jee YH, Garrison P, et al. Differential aging of growth plate cartilage underlies differences in bone length and thus helps determine skeletal proportions. PLoS Biol. 2018; 16: e2005263.
26. Song Hua Y, Lu W, Kuan Z. Effects of different movement modes on plantar pressure distribution patterns in obese and non-obese Chinese children. Gait Posture. 2017; 57: 28-34.
27. Ganea D, Mereuta E, Veresiu S, Rus M, Amortila V. Experimental tests for foot pressure analysis during orthostatic position and gait. InMATEC Web of Conferences. 2017; 112: 08009.