Introduction:
Foot anthropometry measures foot dimensions and plays vital role in the analysis of the difference in the foot anthropometry of flatfooted and non-flatfooted individuals [1]. Combining simple, reliable, and time efficient foot anthropometric variables can be used by clinicians in determining foot types (high arch, normal arch and low arch) [2] and one of the ways is by using staheli’s plantar arch index [3] in determining the presence or absence of flatfoot.
The structure of child’s foot at birth could be seen as flatfoot because of the presence of abundant fat pads on the plantar surface [4] designed to protect the underlying bones against ground reaction forces during walking, but resolves along infancy [5]. Their feet attain features of adult feet approximately 5 to 6 years of age [4]. Failure of their feet to develop properly can lead to flatfoot or pesplanus.
Flatfoot can be of physiological or pathological causes [6]. Pathological or rigid flatfoot leads to significant pain and disabilities such as collagen disorders, and musculoskeletal abnormalities, and often requires treatment [7]. Physiological or flexible flatfoot is developmental and often seen in children in the first decade of life with its contributing factors as ligamentous laxity and overweight [6]. It disappears in a non-weight bearing position and seldom causes disability or requires treatment, although may cause pain when overused [7].
Studies have shown that flatfoot deformity results in shuffling gaits and inability of the foot to absorb shock leading to trauma, osteoarthritis and nerves and blood vessels compression resulting to foot pain [8]. Many studies have been done on the prevalence of flatfoot and its contributing factors like age gender, obesity and type of foot wears [6, 9, 10, 11]. Also foot anthropometric variables of children in some countries have been obtained. Gathering and comparing anthropometric data on the feet of Nigerian children would provide information to be used in the monitoring of flatfoot and making better decisions to reduce occurrence or associated injury via approaches like designing proper foot wears. Therefore, this study was done on a large sample to properly determine flat foot prevalence in Nigerian primary school children, ascertain its association with their personal characteristics and to compare the foot measurements of those with and without flatfoot.
Method and Materials
The research design used was descriptive cross sectional research design. The study was carried out in six primary Schools; Achara-lay out primary school, Zik’s Avenue Primary School, Niger Close Primary School, (Enugu South), Obiagu Road Primary School (Enugu North), Housing Estate Primary School, and Abakpa Nike Primary School (Enugu East) all in Enugu State, Nigeria. A cluster and convenience sampling technique was used. A list of the number of schools in Enugu was obtained from the Ministry of Education, Enugu state. This was used to map out the schools into different local government (Enugu South, Enugu North and Enugu East). At least one school from each of the local government was chosen by simple random technique. Then a convenience sampling technique was used involving 1071 pupils, both males and females, who were willing to participate. The eligibility criteria were; i) Primary school children above six years, ii) children whose inform consent was approved by the parents or guardian, iii) Children who were willing to participate in the study while the exclusion Criteria were i) primary school children who were lower limb amputees, ii) children who had other foot deformities asides flatfeet and iii) those who had congenital or acquired neurological conditions that can affect gait or support.
Electronic weighing scale was used to measure weight of each participant in Kilogram (kg). The participants were asked to stand erect and barefooted with hands placed by the side. Stadiometer was used to measure the height of the participants standing erect and barefooted on the platform of the stadiometer with feet together. This was taken as the distance from the platform to the vertex of the head and was recorded in the nearest 1.0 centimetre. Measuring tape was used in measuring the foot length, the heel circumference, the foot instep, and joint girth with the subject sitting down and the feet off the ground. Venier Caliper was used to measure the forefoot width, mid-foot width, heel width with the subject in standing position. Ink (cyclostyling ink) was dissolved in kerosene and poured on a footpad and used to make foot impression on plain paper by participants. White paper plain sheet was placed on a wooden board placed to provide even surface for making foot impression.
The study was approved by the school authority and health research Ethical Committee, University of Nigeria, Teaching Hospital, Ituku-Ozalla, Enugu where Ethical Clearance Certificate was obtained. Children who met the eligibility criteria were recruited. Every procedure was explained to the school authority and the participants. The study was conducted during their free period in which the children assembled and were instructed on what to do. The participants remained bare footed and their bilateral feet measurements were taken as follow;
In Standing Position,
- Foot length was measured with a tape rule [1] as the distance between the tips of the longest toe anteriorly and the most prominent point of the calcaneal tuberosity [13].
- Forefoot Width was measured with a pair of vernier caliper [14] as the distance between the most medial prominence of the first metatarsophalangeal head and the most lateral prominence of the fifth metatarsophalangeal joint.
- Mid-foot width was measured using a caliper which positioned to align and made contact with the dorsum of the foot laterally and medially to the half of the foot length [2].
- The width of the heel was determined using the caliper as the distance between the most prominent points in the medial and lateral region of the calcaneus [13].
- Arch index was determined using Staheli Arch index; a well validated method of measuring arch index [15].The participants dipped their feet on a foot pad dampened with dissolved cyclostyling ink. The foot was then removed from the pad and the participant made a foot print firmly on a plain sheet of paper attached to a wooden platform [16]. Using a pencil, a line was drawn tangent to the medial fore foot edge and the heel region. From the midpoint of this point, the first perpendicular line was drawn crossing the footprint [10, 17]. This perpendicular line was measured as A. Also, a second perpendicular line B from the heel tangency to the lateral edge of the heel was drawn and measured. The arch index was then calculated by dividing the value of A by the value of B [3]. Any foot with arch index value was >1.15 Staheli was considered as flatfoot [3]. This is shown below.
 |
Figure 1: Measurement of Plantar Arch Index. The image of a footprint on plain paper is shown.
A is the width of the narrowest part of the mid foot and B is the width of the widest part of the hind foot. Arch Index (A/I) was calculated by dividing the length of A by the length of B. |
In sitting Position,
- The joint girth or ball joint: it was determined using a tape rule by measuring completely round the metatarsophalengeal joint of the foot [18].
- Foot instep or Instep Circumference: the instep circumference was measured using a tape rule, measuring completely round the navicular bone. It is the part of the foot with the tallest bone. It is in between the joint girth and the ankle [19].
- Heel circumference: it was obtained using a tape rule by measuring completely round the ankle joint and the heel [18]. Heel circumference is posterior to the foot instep.
The foot anthropometric variables were analyzed descriptively obtaining the mean and standard deviation. Then the prevalence of flatfoot among primary school children was analyzed inferentially using chi-square. ANOVA (Analysis of variance) was used in comparing the foot anthropometric variables of the pupils with no flatfoot, unilateral and bilateral flatfoot. Independent t-test was used in comparing the foot anthropometric variables of children with flatfoot and those without flatfoot using SPSS 20.0 version (SPSS inc. Chicago, IL).
Result
Table 1: Descriptive Statistics Showing Personal Characteristics of Primary School Children in Enugu State. |
Gender |
n (%) |
Flatfoot n (%) |
No flatfoot n (%)
|
Male |
526 (49.1) |
84 (16) |
442 (84.0) |
Female |
545 (50.9) |
74 (13.6) |
471 (86.4) |
Table 1 showed that 1071 pupils comprising 526 (49.1%) males and 545 (50.9%) females participated in this study. 16% of males and 13.6% of females have flatfoot while 84% of males and 86.4% of females have no flatfoot.
Table 2: Descriptive and Inferential Statistics Showing Association between Side of Flatfoot and Personal Characteristics of Primary School Children in Enugu State. |
Variables |
n |
Flatfoot |
Χ2 |
P-value |
| |
|
Unilateral % |
Bilateral % |
|
|
| Gender |
Male |
84 |
64.3 |
30 |
0.696 |
0.325 |
Female |
74 |
71.6 |
41.2 |
|
|
Age (years) |
6 |
27 |
66.7 |
33.3 |
20.344 |
0.009* |
7 |
28 |
42.9 |
57.1 |
|
|
8 |
16 |
81.2 |
18.8 |
|
|
9 |
21 |
76.2 |
23.8 |
|
|
10 |
21 |
52.4 |
47.6 |
|
|
11 |
18 |
72.2 |
27.8 |
|
|
12 |
16 |
93.8 |
6.2 |
|
|
13 |
5 |
60 |
40 |
|
|
14 |
6 |
100 |
0 |
|
|
15 |
0 |
0 |
0 |
|
|
Table 2 showed that out of 1071 pupils that participated in this study, 158 (14.8%) of them have flatfoot. 64.3% of males and 71.6% of female participants have unilateral flatfoot while, 30% of male and 41.2% of females participants have bilateral flatfoot. Chi-Square analysis showed that no significant association (p-0.325) between the side of flatfoot and the gender of the pupil. A significant association (p=0.009) was obtained between age and side of flatfoot. In essence, the side of foot affected is contingent with age.
Table 3: Comparison of Body Anthropometric Variables of Pupils with Normal Foot, Unilateral and Bilateral Flatfoot using ANOVA. |
Variables |
Flatfoot |
No flatfoot X±SD |
F-value |
P-value |
| |
Unilateral X±SD |
Bilateral X±SD |
|
|
|
Weight (kg) |
32.48±9.23 |
29.49±9.44 |
31.6±8.49 |
1.95 |
0.142 |
Height (m) |
136.7±13.48 |
130.2±10.48 |
139±13.16 |
14.02 |
0.001* |
BMI (kg/m2) |
17.12±2.78 |
17.26±3.83 |
16.04±2.71 |
11.02 |
0.001* |
Table 3 shows the body anthropometric variables (weight, height and body mass index) of those who have no flatfoot, those who have unilateral flatfoot and bilateral flatfoot, with their p-value, mean and standard deviation. No significant difference was obtained in the weight of the three groups. There was a significant difference in height and BMI across the 3 groups. This necessitated a post hoc analysis (Table 5) to determine the source of the significant difference.
Table 4: Bonferroni Post Hoc Analysis Showing the Source of the Significant Difference in Height of Pupils across the Groups. |
Height |
| |
No Flatfoot |
No Flatfoot |
Bilateral Flatfoot |
No Flatfoot |
------ |
0.099 |
0.001* |
Unilateral Flatfoot |
|
------ |
0.001* |
Bilateral Flatfoot |
|
|
----- |
Bonferroni Post Hoc analysis (table 4) showed that there was a significant increase in height of those who have bilateral flatfoot when compared to those who have no flatfoot. Also those who have bilateral flatfoot have a significant increase in height when compared to those who have unilateral flatfoot but there was no significant difference in height comparing those without flatfoot and unilateral flatfoot.
Table 5: Bonferroni Post Hoc Analysis Showing the Source of the Significant Difference in Body Mass Index of Pupils across the Groups. |
Body Mass Index |
| |
No Flatfoot |
No Flatfoot |
Bilateral Flatfoot |
No Flatfoot |
------ |
0.001* |
0.007* |
Unilateral Flatfoot |
|
------ |
1.00 |
Bilateral Flatfoot |
|
|
----- |
Table 5 showed that there was a significant increase in the body mass index of those with unilateral flatfoot when compared to those without flatfoot and also an increase in those with bilateral flatfoot when compared to those without flatfoot, but there was no significant difference in body mass index of those with unilateral and bilateral flatfoot.
Table 6: Comparison of Right Foot Anthropometric Variable of Primary School Children with and without Flat Foot in Enugu State. |
Variables of right foot (cm) |
Non-flatfoot individuals [n=954] Mean±SD |
Flatfoot individuals [n=117] Mean±SD |
t-value |
P-value |
Foot length |
24.27±2.56 |
23.71±2.37 |
-2.426 |
0.016* |
Forefoot Width |
5.72±0.86 |
5.54±0.87 |
2.164 |
0.032* |
Mid foot Width |
4.83±0.81 |
4.79±0.89 |
-0.695 |
0.488 |
Heel Width |
3.23±1.51 |
3.15±0.66 |
-1.989 |
0.048* |
Ball girth |
20.51±2.03 |
20.11±1.85 |
-1.752 |
0.082 |
Foot Insstep |
21.77±2.46 |
21.53±2.74 |
-0.894 |
0.373 |
Heel Circumference |
21.77±2.46 |
27.87±2.80 |
-3.798 |
0.001* |
Table 6 showed the right foot anthropometric variables of primary school children in Enugu State. 954 (89.1%) pupils do not have flat foot on the right foot while 117 (10.9%) pupils have flatfoot on the right. It was observed that pupils who don’t have right flatfoot have a higher mean value for all the right foot anthropometric variables than those with right flatfoot except the arch index. Those with flatfoot have a higher mean value for arch index than those who don’t have. Independent t-test shows that there was a significant difference (p<0.05) in foot length (p=0.016), forefoot width (p=0.032), heel width (p=0.048), heel Circumference (p=0.001) as well as arch index (p=0.001).
Table 7: Comparison of Left Foot Anthropometric Variable of Primary School Children with and without Flat Foot in Enugu State. |
Variables of left foot (cm) |
Non-flatfoot individuals [n=954] Mean±SD |
Flatfoot individuals [n=117] Mean±SD |
t-value |
P-value |
Foot length |
24.71±8.85 |
23.82±2.37 |
-2.06 |
0.041* |
Forefoot Width |
5.65±0.80 |
5.47±0.82 |
-1.896 |
0.060 |
Mid foot Width |
4.77±0.80 |
4.72±0.74 |
-0.511 |
0.610 |
Heel Width |
3.19±0.80 |
3.05±0.68 |
-0.995 |
0.321 |
Ball girth |
20.63±2.23 |
20.20±2.54 |
-1.972 |
0.051 |
Foot Insstep |
21.83±2.35 |
21.49±2.61 |
-1.199 |
0.233 |
Heel Circumference |
28.75±3.10 |
28.05±2.88 |
-3.798 |
0.028* |
Table 7 showed the left foot anthropometric variables of the pupils. 977 (91.2%) pupils do not have flat foot on the left foot while 94 (8.8%) pupils have flatfoot on the left foot. It was observed that pupils who don’t have flatfoot have a higher mean value for all the left foot anthropometric variables than those who have flatfoot except the arch index. Those who have flatfoot have a higher mean value in arch index than those who don’t have flatfoot. Independent t-test showed that there was significant difference (p<0.05) in foot length (p=0.041), heel circumference (p=0.028) as well as arch index (p=0.001).
Discussion
The present study showed that the prevalence of flatfoot in primary school children above the age of six was 14.75%. This is different from the findings of earlier study. Pfeiffer et al, (2014) [6] reported a prevalence of 44% in 3 to 6 year old children, Echarri & Forriol, (2003) [19] reported a prevalence of 70% in children aged 3 to 4 years, but closer to the findings of Ezema et al, (2014) [9] and El et al, (2006) [20] who reported a lower prevalence of 22.4% and 17% in children with a mean age of 9 years respectively. The higher prevalence in the former may be due to the fact that these researchers involved children who were below 6 years, because it is expected that a child’s foot could be seen as flatfoot below the age of 6 due to the presence of fat pad at the planter surface, which is supposed to be resolved and attain a feature of adult foot approximately 6 years of age [4]. Also the prevalence of unilateral flatfoot was higher than bilateral flatfoot. This was in contrast with Ezema et al, (2014) [9] who reported a higher prevalence in bilateral flatfoot. This could be as a result of lesser sample size used by Ezema et al, (2014) [9], unlike this present study that involved 1071 participants. The higher number of participants could improve the level of accuracy of the result. Comparing the prevalence of flatfoot with body anthropometry (height, weight and body mass index), the result showed that there was a significant increase in height of those who have bilateral flatfoot when compared to those who have unilateral flatfoot and those who do not have flatfoot respectively. This suggests that there could be a higher risk of flatfoot occurrence with increase in height. Also, there is a significant increase in the body mass index of those with unilateral flatfoot when compared to those without flatfoot and also an increase in body mass index of those who have bilateral when compared to those without flatfoot. This is in line with other studies [9, 21] that reported a positive correlation between flatfoot and body mass index although this study went beyond classifying flatfoot into unilateral and bilateral. This shows that increase in body mass index could result to collapse of the medial longitudinal ligaments responsible for the formation of the medial arch of the foot resulting to flatfoot.
Comparing the foot anthropometric variables of children with flatfoot and those without flatfoot, the result showed that the mean values of both right and left foot parameters of those who do not have flatfoot are higher than that of those who have flatfoot. On the right foot, there was a significant increase in the foot length, forefoot width, heel width, and Heel Circumference whereas on the left foot, there was a significant increase in the foot length and heel circumference of children without flatfoot. This variation in the left and right foot could be as a result of the impact of the collapse of the medial longitudinal arch being more pronounced on the right foot than the left foot or there was an error which occurred during the measurement. The significant difference in some of the foot anthropometry of those with flatfoot and those without flatfoot could be as a result of foot structure modification such as Posterior tibial tendon dysfunction leading to the flattening of the medial longitudinal arch, forefoot abduction and the hind foot valgus [22]. The result of this study is in contrast with the findings of Umar and Tafida, (2013) [23] who recorded a significant difference in all the parameters except foot length when he compared the foot anthropometric variables of children with and without flatfoot. Also Umar and Adeyemi, (2010) [1] reported a higher mean value in the foot parameters of those who do not have flat foot than those who have flat foot and significant difference in all except in foot length. The variation between this present study and the previous study could be attributed to the different foot anthropometry used. The foot anthropometry used by the previous studies [1, 23] were Medial Malleoli height, Navicular height, Foot length, Lateral Malleoli height and Transverse Arch length while that used in this study were foot length, forefoot width, heel width, mid foot width, foot instep, ball girth, heel circumference and arch index.
Conclusion
The study showed significant differences between some foot anthropometry of children with flatfoot and those without flatfoot. Foot anthropometry should be used for early detection of flatfoot by clinicians and manufacturing of appropriate footwear sizes by footwear Manufacturers so as to minimize foot pain, injuries and deformities. Children with flatfoot should be given proper management such as construction of foot insoles in foot wear, physical education etc. Further studies are recommended on the relationship between height of an individual and flatfoot as previous studies dwelt on association between weight and flatfoot. In addition, a longitudinal study is needed to demonstrate the relationship between gender, varying body mass index (under-weight, normal weight, over-weight and obesity) and flatfoot.
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