title: Medial Longitudinal Arch Development of Children Aged 7 to 9 Years: Longitudinal Investigation.
abstract: BACKGROUND
  It is unclear at what age the medial longitudinal arch (MLA) of the foot becomes stable in children. The influence of footwear on MLA development also is unknown.
  
  
  OBJECTIVE
  The purpose of this study was to examine the MLA development of children using a longitudinal approach. The relationship between wearing different types of footwear and MLA development also was explored longitudinally.
  
  
  METHODS
  This was a longitudinal cohort observational study.
  
  
  METHODS
  The MLA of 111 healthy children (mean age=6.9 years, SD=0.3) was evaluated using 3 parameters (arch index [AI], midfoot peak pressure [PP], and maximum force [MF]) extracted from dynamic foot loading measurements at baseline (t0), 10-month follow-up (t1), and 22-month follow-up (t2). Information on footwear usage was surveyed. Linear mixed modeling was used to test for differences in MLA over time.
  
  
  RESULTS
  The MLA of the children remained stable over time (AI: t0/t1/t2=0.25 [95% confidence interval (CI)=0.24, 0.26]/0.25 [95% CI=0.24, 0.26]/0.25 [95% CI=0.24, 0.26]; P=.95). When the children's sex was considered, the AI of boys decreased (higher arch) with age (0.26 [95% CI=0.24, 0.27]/0.25 [95% CI=0.24, 0.27]/0.25 [95% CI=0.23, 0.27]; P=.02). Boys also displayed a flatter MLA than girls at age 6.9 years (AI: mean difference=0.02 [95% CI=0.01, 0.04]; P=.02). At baseline, children who wore closed-toe shoes displayed the lowest MLA overall (AI: closed-toe shoes/sandals/slippers=0.26 [95% CI=0.24, 0.28]/0.24 [95% CI=0.23, 0.25]/0.25 [95% CI=0.24, 0.26]; P<.01). Children who used slippers at toddlers' age experienced a higher PP (flatter arch) in later childhood than those who wore sandals (mean difference=31.60 kPa [95% CI=1.44, 61.75]; post hoc P=.04).
  
  
  CONCLUSIONS
  Information on the type of footwear worn was self-reported and, therefore, may be subjected to recall bias.
  
  
  CONCLUSIONS
  The MLA of children remained stable from 7 to 9 years of age. The child's sex and the type of footwear worn during childhood may influence MLA development.
authors.affiliation: J.W.K. Tong, PhD, Allied Health Specialties, KK Women's and Children's Hospital, Singapore and Physical Education and Sports Science Academic Group, Nanyang Technological University, Singapore.
authors.forename: Jasper W K
authors.initials: JW
authors.lastname: Tong
authors.affiliation: P.W. Kong, PhD, Physical Education and Sports Science Academic Group, Nanyang Technological University, 1 Nanyang Walk National Institute of Education, Singapore 637616. puiwah.kong@nie.edu.sg.
authors.forename: Pui W
authors.initials: PW
authors.lastname: Kong
mesh_terms: D000367:Age Factors; D002648:Child; D005260:Female; D005528:Foot / Q000033:anatomy & histology / Q000254:growth & development* / Q000502:physiology*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D011312:Pressure; D012737:Sex Factors; D012775:Shoes; D016474:Weight-Bearing