PEDIATRICS Vol. 118 No. 2 August 2006, pp. 634-639 (doi:10.1542/peds.2005-2126)
ARTICLE |
Prevalence of Flat Foot in Preschool-Aged Children
a Department of Orthopedics, Medical University of Vienna, Vienna, Austria
b Institute of Scientific Computing, University of Vienna, Vienna, Austria
c Center for Anatomy and Cell Biology, Medical University of Vienna, Vienna, Austria
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ABSTRACT |
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 TOP ABSTRACT METHODSRESULTSDISCUSSIONCONCLUSIONSREFERENCES |
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OBJECTIVES. Our aim with this study was to establish the prevalence of flat foot in a population of 3- to 6-year-old children to evaluate cofactors such as age, weight, and gender and to estimate the number of unnecessary treatments performed.
METHODS. A total of 835 children (411 girls and 424 boys) were included in this study. The clinical diagnosis of flat foot was based on a valgus position of the heel and a poor formation of the arch. Feet of the children were scanned (while they were in a standing position) by using a laser surface scanner, and rearfoot angle was measured. Rearfoot angle was defined as the angle of the upper Achilles tendon and the distal extension of the rearfoot.
RESULTS. Prevalence of flexible flat foot in the group of 3- to 6-year-old children was 44%. Prevalence of pathological flat foot was <1%. Ten percent of the children were wearing arch supports. The prevalence of flat foot decreases significantly with age: in the group of 3-year-old children 54% showed a flat foot, whereas in the group of 6-year-old children only 24% had a flat foot. Average rearfoot angle was 5.5° of valgus. Boys had a significant greater tendency for flat foot than girls: the prevalence of flat foot in boys was 52% and 36% in girls. Thirteen percent of the children were overweight or obese. Significant differences in prevalence of flat foot between overweight, obese, and normal-weight children were observed.
CONCLUSIONS. This study is the first to use a three-dimensional laser surface scanner to measure the rearfoot valgus in preschool-aged children. The data demonstrate that the prevalence of flat foot is influenced by 3 factors: age, gender, and weight. In overweight children and in boys, a highly significant prevalence of flat foot was observed; in addition, a retarded development of the medial arch in the boys was discovered. At the time of the study, >90% of the treatments were unnecessary.
Key Words: foot • rearfoot angle • preschool children • flat foot • correlating factors
Infants are born with flat feet, and the longitudinal arch develops naturally during the first decade of life.1–3 Flat foot becomes apparent when children begin standing and often causes concern among parents. It is a common reason for parents to consult orthopedic surgeons, and parents usually want their children to have treatment to avoid the flat-footedness that they themselves endured as children.
Traditionally, flat-footed children have been treated with arch supports or corrective shoes to improve the arch, but authors of recent studies doubt the effectiveness of these treatments and are of the opinion that flat foot is normal in early childhood and resolves spontaneously without treatment.4–6 However, definition of flat foot in children is surrounded by confusion, and general classification differentiates between flat foot resulting from physiological and pathological causes. Pathological or rigid flat foot has multiple etiologies and leads to significant pain and disability, often requiring treatment. Physiological flat foot is considered developmental and is often seen in children in the first decade of life; contributing factors include ligamentous laxity and overweight. The flat contour is pronounced with weight bearing, but the arch can be reconstituted with extension of the great toe or when the child stands on his or her tiptoes.5–7 Unfortunately, flexible flat-foot treatment indications remain controversial. Many authors suggest that flexible flat foot usually does not cause disability and that asymptomatic children should not be burdened with inserts. Despite this knowledge, a considerable number of arch supports are prescribed unnecessarily.6,8
Our aim with this study was to establish the prevalence of flat foot in a population of 3- to 6-year-old children, to evaluate cofactors such as age, weight, and gender, and to estimate the number of unnecessary treatments performed.
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METHODS |
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TOPABSTRACTMETHODSRESULTSDISCUSSIONCONCLUSIONSREFERENCES |
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Nine hundred forty-eight children (468 girls and 480 boys) between the age of 3 and 6 years from 14 kindergartens in Austria were studied. Children were divided into 4 groups according to their age (3, 4, 5, and 6 years) and into groups of urban or rural dwellers (Table 1).
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Clinical diagnosis of flat foot was based on a valgus position of the heel and the formation of the medial arch on weight bearing: we considered a foot to be normal if the medial arch looked normal, even if it was slightly impressed. If the medial arch was not visible, it was graded as moderate flat foot; classification as severe flat foot meant that the medial border of the foot was convex. The children were observed from the rear while weight bearing; then, if the heel was in a valgus position, the child was asked to stand on his or her tiptoes to see if reconstitution of the arch was possible. Flat foot was classified according to the directions of the German orthopedic association into flexible and pathological flat foot.9 Preschool-aged children with flexible flat foot have a valgus position <20° and active correction is possible, whereas pathological flat foot is defined by a valgus position >20° and/or a disability for reconstitution of the valgus.
Both feet of the children were scanned (while they were in a standing position) by using a laser surface scanner (Pedus, Human Solution Corp, Kaiserslautern, Germany),10 and assessments were conducted on the laser scan image. The measurement and selection system consisted of a three-dimensional laser scanner (3 charge-coupled device cameras, 3 lasers) and a PC-control unit. Laser images could be rotated on the monitor to achieve the most suitable view for carrying out assessments. After positioning the laser scan image in a rearfoot view, the rearfoot angle was measured with a 2-arm goniometer on the image itself. Rearfoot angle was defined as the angle of the upper Achilles tendon and the distal extension of the rearfoot. A valgus between 0° and 4° was classified as normal, a valgus between 5° and 20° was classified as physiological flat foot, and rearfoot valgus of 
20° was classified as pathological flat foot.
The weight of each child was measured on a scale with an accuracy of ±100 g; their height was measured by a stadiometer. The BMI was calculated for every child by dividing the weight by the square of the height. Children were classified by their BMI score according to German reference data into underweight (3rd percentile), normal weight (3rd–90th percentile), overweight (90th–97th percentile), and obese (97th percentile).11
Children were excluded if they presented with:
- evidence of fixed-foot deformity or a previous intervention that had been described (such as clubfoot or surgery in the past);
- inability to perform the laser scan; or
- any kind of pain in the lower limb or injuries that had required a period of non–weight bearing at the time of the study.
One hundred thirteen children were excluded from the study on the basis of these criteria.
The study protocol is shown in Table 2.
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In the distribution of the valgus, variable nonparametric statistics were chosen to identify whether the variables "gender," "child age," and "BMI" have influence on the valgus.
To identify a statistical significance for the impact of the 3 variables, Kruskal-Wallis tests were performed.
For the correlations, the nonparametric Spearman correlation was computed, because normality could not be assumed for any of those variables. For the prevalence of flat foot a logistic-regression model was estimated (Tables 3–5):
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P(\mathrm|<|flat foot|>|
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The data were analyzed by using SPSS 12.0 (SPSS Inc, Chicago, IL).
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RESULTS |
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TOPABSTRACTMETHODSRESULTSDISCUSSIONCONCLUSIONSREFERENCES |
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A total of 835 children (411 girls and 424 boys) were included in this study. The mean age of the children was 4 years, 5 month (range: 3–6 years).
Prevalence of flexible flat foot in this group of 3- to 6-year-old children was 44% (n = 365), and the prevalence of pathological flat foot was <1% (n = 7); in 3 cases an active correction of the valgus was not possible (3 boys, normal weight, 4 years old; valgus: 11–12°), and 4 children showed a valgus >20° (3 girls, 3 years old, normal weight, and 1 boy, 5 years old, normal weight).
Our data analyses showed that 3 variables had a significant relationship to the prevalence of flexible flat foot: age, gender, and weight.
The prevalence of flat foot decreases significantly with age: in the group of 3-year-old children, 54% showed a flat foot, whereas in the group of 6-year-old children only 24% had a flat foot (P < 0001) (Table 6). The average rearfoot angle was 5.5° of valgus (range: 2–24°). The valgus varied significantly with age (P < .01): for 3-year-old children, the mean valgus was 6.4° (range: 2–24°), for 4-year-old children, 5.6° (range: 2–21°), for the 5-year-old children, 5.3° (range: 2–20°), and for the 6-year-old children, 4.5° (range: 2–13°) (Table 7).
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The boys had a significant greater tendency for flat foot than the girls: the prevalence of flat foot in boys was 52%, and in girls the prevalence was 36% (P < .01) (Table 8). Mean valgus in the boys was 5.8° and in the girls was 5.1°. The rearfoot valgus in the boys was greater in every age group (Table 7). Prevalence of flat foot in the boys decreased continuously from 71% to 32% from 3 to 6 years, whereas in the girls the prevalence varied slowly between 3 and 5 years and decreased rapidly between 5 and 6 years from 39% to 16% (Fig 1).
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Thirteen percent of the children were overweight or obese. Significant differences in prevalence of flat foot between overweight (51%), obese (62%), and normal-weight children (42%) were observed (P < .05) (Table 9). Mean valgus in normal-weight children was 5.4°, in overweight children, 5.9°, and in obese children, 6.2°.
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There were no significant differences between the rural and urban populations.
The influence of age, BMI, and gender was estimated by a logistic-regression model (Table 3–5). The results are shown in Table 3. Each deviation from normal weight increases the risk of flat foot. The risk is almost twice as much for underweight children (1.995). Overweight children have a 27% higher risk, and obese children have a risk almost 3 times as much as the base rate (2.777).
The risk of flat foot is more than twice as much for boys than girls (2.231). The percentage of children having flat foot decreases over time, which is indicated by a 36.8% decrease of the risk of flat-footedness per year.
Apparently there is no interaction between BMI and gender with respect to the prediction of flat-footedness. Therefore, we can see that the overweight boys have the highest risk for flat foot. Of the overweight and obese boys, 55.6% have a flat foot (Fig 2).
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A great number of children were being treated with arch supports (10%), most without having a pathological flat foot according to the criteria that we used in this work.
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DISCUSSION |
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TOPABSTRACTMETHODSRESULTSDISCUSSIONCONCLUSIONSREFERENCES |
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Our study demonstrates that the development of the medial arch of the foot in preschool-aged children is influenced by 3 factors: age, gender, and weight.
Age is the primary predictive factor for flat feet, and the prevalence of flat foot progressively decreases with increasing age. In this study, the mean prevalence of flat foot in preschool-aged children was 44%; the prevalence decreased from 54% in 3-year-old children to 24% in 6-year-old children, and the probability of flat-footedness decreased by 36.8% per year.
There are fewer reports in the literature concerning the prevalence of flat foot in preschool-aged children, but our findings differ slightly from the results in these studies. Echarri and Forriol12 reported a prevalence of flat foot of 70% in 3- and 4-year-old children and 40% in 5- to 8-year-old children; Lin et al13 found that the prevalence of flat foot decreased from 57% in 2- to 3-year-old children to 21% in 5- to 6-year-old children; Roa and Joseph2 reported prevalences that varied between 14.9% (6 years) and 9.1% (7 years); and Rose et al14 found a prevalence of 42.5% in preschool-aged children. The difference could be explained by the different evaluated methods; Lin et al graded the foot by determining the medial arch, Echarri and Forriol, Roa and Joseph, and Rose et al used footprint measurements, and we used the rearfoot angle as criterion. Footprint parameters have been used often to classify foot structure, but it has been stated that footprint methods are influenced by body composition. Preschool-aged children, especially, frequently have a medial pressure pattern that is not an indicator for abnormality in this age.5,14,15 Many authors doubt the reliability of footprint methods for description of the longitudinal arch.1,12,14 The rearfoot valgus during weight bearing is commonly used as a criterion in the evaluation of flat foot in children.16 Results are reliable because the Achilles tendon and the heel bisection are used as a reference, and the Achilles tendon is always perpendicular to the weight-bearing surface at the level of the ankle joint regardless of whether the foot is valgus or cavus.16 In our study the average valgus varied significantly with age: the 3-year-old children had a mean valgus of 6.4° (range: 2–24°), but the valgus was reduced to 4.5° (range: 2–13°) in the 6-year-old children. Our findings in the group of 6-year-old children are similar to the results published by Sobel et al,16 who state that the rearfoot angle reduces with age to an average angle of 4° of valgus, attained at 
7 years. Medial arch improves with increasing age, very quickly up to 6 years, slowly up to 10 years, and without significant change thereafter.1–3,6,7
In our study, the boys had a significant greater tendency for flat foot than the girls: the prevalence of flat foot in boys was 52% and in girls was 36%. The rearfoot valgus in boys was greater in every age group. In addition, a significant difference in the development of the rearfoot valgus between boys and girls was discovered within the studied sample: when analyzing the mean valgus in the different age groups, boys had a retarded development of the rearfoot valgus of 1 year compared with the girls (Table 7; Fig 1).
It has been reported that obese children have a greater tendency for flat foot than normal-weight children,8,17–19 and our results generally agree with those found elsewhere. However, we have demonstrated that the probability of flat-footedness in overweight and obese children is up to 3 times higher than in normal-weight children. Dowling et al17 reported structural changes, especially a flattening of the longitudinal arch, associated with obesity, but whether this changing is reversible and whether obese children will suffer later from foot pathologies is not clear. With respect to present data and the increasing number of obese and overweight children, we can suppose that the number of flat-footed children and their clinical relevance will increase in the future.
Ten percent of the children were treated with arch supports, most without having the diagnostic criteria for a pathological flat foot. Less than 1% of our pupils had a rearfoot valgus >20° or had a rigid flat foot. Indication for an orthopedic treatment of physiological flat foot remains controversial. Traditionally, flat foot has been treated with arch supports or corrective shoes, but recent studies have failed to prove the effectiveness of such treatment.4,6 Our data confirm that the physiological flat foot improves naturally with age, and we agree with Wenger et al6 and Hefti and Brunner,5 who state that a flexible flat foot does not need therapy. In addition, Roa and Joseph2 and Sachithanandam and Joseph19 postulated an association between wearing shoes and the prevalence of flat foot. The authors state that children who wear shoes in early childhood showed a higher prevalence of flat foot than those who where unshod before 6 years of age. By wearing shoes during this critical time, intrinsic foot muscles are weakened and the medial arch improves inappropriately.
Arch supports and corrective shoes are uncomfortable for the child. Authors have failed to prove an effect of arch supports on the development of the medial arch of flexible flat foot; on the contrary, some authors state that arch supports weaken the foot muscles and perpetuate the problem.4,6,8 Treatment of children with physiological flat foot is ineffective and produces enormous costs for parents and health service providers.8 Children with typical flexible flat foot should not be burdened with arch supports or corrective shoes. We recommend orthopedic treatment for children with symptomatic flat foot or with pathological flat foot according to the criteria we used in this work; appropriate treatment depends on the nature of the pathology.
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CONCLUSIONS |
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TOPABSTRACTMETHODSRESULTSDISCUSSIONCONCLUSIONSREFERENCES |
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Our study is the first using a three-dimensional laser surface scanner to measure the rearfoot valgus in preschool-aged children. The data demonstrate that the prevalence of flat foot is influenced by 3 factors: age, gender, and weight. Especially in overweight children and in boys a highly significant prevalence of flat foot was observed; in addition, retarded development of the medial arch in the boys was discovered. At the time of the study, >90% of the treatments performed were unnecessary.
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FOOTNOTES |
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Accepted Mar 20, 2006.
Address correspondence to Martin Pfeiffer, MD, Department of Orthopedics, Medical University of Vienna, Waehringer Gürtel 18-20, 1090 Vienna, Austria. E-mail: martin.pfeiffer{at}gmx.at
The authors have indicated they have no financial relationships relevant to this article to disclose.
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REFERENCES |
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PEDIATRICS (ISSN 1098-4275). ©2006 by the American Academy of Pediatrics
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