Growing feet: Foot metrics and shoe fit in South African school-aged children and adolescents

Abstract

ENGLISH ABSTRACT : The foot undergoes numerous developmental changes during the first few years of life. Due to this continued development of the foot during childhood, it leaves the feet of children exposed to external influences. Factors such as age, gender and footwear can have a significant impact on the development of the foot. The primary aim of the study was to investigate whether the foot metrics of South African children and adolescents are influenced by age, gender, race and body mass index (BMI). A secondary aim of this study was to establish if South African children and adolescents wear well-fitting shoes. A total of 568 children and adolescents between the ages of six and eighteen years from schools within the Western Cape, South Africa, participated in the study. Static foot length and width were measured with a self-manufactured calliper and school shoe length and width were measured with a flexible straw and sliding calliper respectively. Shoe fit was determined by the difference between the width of the foot and the width of the shoe as well as the difference between the length of the shoe and the length of the foot. A toe allowance was also considered. Dynamic arch index (AI) was measured by using the Emed c50 pressure plate (Novel GmbH, Munich, Germany). The effect of age, gender, race, and BMI on foot length, width and dynamic AI was evaluated, as well as its effect on the shoe fit. Statistical analyses were done by using the one-way ANOVA and two-way ANOVA with Fisher’s least significant differences as post-hoc test, as well as its effect on the shoe fit. Cohen’s effect size (ES) for each parameter was calculated to determine practical differences. Gender and race significantly (p < 0.05) influenced the foot length and width of children and adolescents. Girls had shorter and narrower feet than boys. The girls showed no significant increase in foot length and width measurements after 12 years of age. White children had significantly (p < 0.05) and medium practically longer and wider feet, and a lower AI (p < 0.05) than the brown children and adolescents. Statistically (p < 0.05) and practically significant differences in foot length, width and AI were found between the different BMI categories. Furthermore, results show that 67 percent of the children and adolescents wore ill-fitting shoes when looking at the length of school shoes compared to the length of the feet, taking toe allowance into account. There was a significant difference in shoe fit for the width between genders, with girls wearing more tight fitting shoes than boys. Significant differences were seen in the shoe fit for length measurements between the different races, where the brown children’s shoes were a tighter fit than the white children’s shoes. The obese South African children have worn shoes that were too narrow for their feet.

AFRIKAANSE OPSOMMING : Gedurende die eerste paar jaar van die mens se lewe ondergaan die voet verskeie stadiums van ontwikkeling. Weens hierdie voortdurende ontwikkeling gedurende kinderjare, is die groeiende voet vatbaar vir eksterne invloede. Faktore soos ouderdom, geslag en skoene kan ‘n beduidende invloed op die ontwikkeling van die voet hê. Die primêre doel van die studie was om te bepaal of ouderdom, geslag, ras en liggaamsmassa-indeks (LMI) ‘n betekenisvolle effek op die voetafmetings van SuidAfrikaanse kinders en adolessente het. Die sekondêre doel van die studie was om vas te stel of die Suid-Afrikaanse kinders en adolessente die regte grootte skoene vir hul voetgrootte dra. ‘n Totaal van 586 kinders en adolessente tussen die ouderdom van ses en agtien jaar, uit skole van die Wes-Kaap, Suid-Afrika, het aan die studie deelgeneem. Die kinders se voetlengtes en -breedtes is met ‘n selfgemaakte kaliper gemeet terwyl die sportskoenlengtes en -breedtes en skoolskoenlengtes en -breedtes onderskeidelik met ‘n buigsame strooitjie en glypasser gemeet is. Die verhouding tussen voet- en skoengrootte is bepaal deur die voetlengte en -breedte onderskeidelik af te trek van die skoenlengte en -breedte. Toonspasie is in ag geneem met die bepaling van die gepaste skoengrootte. ‘n Drukplatform (Emedc50) is gebruik om die voetbrugindeks te meet (Novel GmbH, München, Duitsland). Die effek wat ouderdom, geslag, ras en LMI op die voetlengte, -breedte en voetbrugindeks gespeel het is bepaal, asook die effek daarvan op hoe die skoen die voetgrootte pas. ‘n Eenrigting ANOVA en 2- rigting ANOVA is gebruik tydens die ontleding van die data met Fisher se minste beduidende verskille as post-hoc analise. Cohen se effekgrootte (ES) is gebruik om praktiese verskille tussen die veranderlikes te bepaal. Die resultate van die studie toon betekenisvolle (p < 0.05) verskille in die voetlengte en -breedte tussen seuns en dogters, asook die rasse vanaf 12 jarige ouderdom. Die dogters se voete was oor die algemeen nouer as die van die seuns. Na 12 jarige ouderdom was daar ‘n afplatting in die groei van die dogters se voete in beide lengte en wydte. Die wit kinders se voete was betekenisvol (p < 0.05) en prakties betekenisvol (medium) langer en breër as die voete van die bruin kinders. Daar was egter slegs ‘n medium prakties betekenisvolle verskil in die voetbrugindeks, met die wit kinders wat ‘n laer voetbrugindeks gehad het as die bruin kinders en adolessente. Die verskillende LMI kategorieë het ook betekenisvolle verskille in die voetlengte enbreedte en voetbrugindeks gehad. Resultate het getoon dat 67 persent van die SuidAfrikaanse kinders en adolessente swakpassende skoolskoene dra. Die gevolgtrekking is gemaak nadat die voetlengte afgetrek is van die skoolskoenlengte, met toonspasie wat ook in berekening gebring is. Betekenisvolle verskille tussen seuns en dogters dui daarop dat die dogters se skoene, in terme van breedte, swakker pas as seuns se skoene. Die bruin kinders se skoene was ook betekenisvol korter in verhouding tot hul voetlengte teenoor die wit kinders se skoene. Die SuidAfrikaanse vetsugtige kinders het skoene gedra wat te nou was vir hulle voete.