title: The Relationship Between Arch Height and Arch FlexibilityA Proposed Arch Flexibility Classification System for the Description of Multidimensional Foot Structure.
abstract: BACKGROUND
  The correlation between arch structure and injury may be related to the fact that foot structure influences foot function. Foot structure is often defined by arch height, although arch flexibility may be just as important to form a more complete description. We propose an arch flexibility classification system, analogous to arch height classification, and then use the classification system to examine the relationship between arch flexibility and arch height.
  
  
  METHODS
  Arch height index was calculated in 1,124 incoming military cadets, of whom 1,056 had usable data. By measuring arch height during both sitting and standing, a measurement of arch flexibility could also be calculated. These values were used to create five arch flexibility categories: very stiff, stiff, neutral, flexible, and very flexible. The distribution of arch flexibility types among arch height categories was statistically compared.
  
  
  RESULTS
  The goodness of fit test showed a disproportionate number of each arch flexibility type in each of the arch height categories (P < .01). The largest proportion of cavus feet was very stiff and the smallest proportion was very flexible. Conversely, the largest proportion of planus feet was very flexible and the smallest proportion was very stiff.
  
  
  CONCLUSIONS
  The results of this research support the common belief that cavus feet tend to be very stiff and planus feet tend to be very flexible.
authors.forename: Rebecca Avrin
authors.initials: RA
authors.lastname: Zifchock
authors.forename: Christal
authors.initials: C
authors.lastname: Theriot
authors.forename: Howard J
authors.initials: HJ
authors.lastname: Hillstrom
authors.forename: Jinsup
authors.initials: J
authors.lastname: Song
authors.forename: Michael
authors.initials: M
authors.lastname: Neary
mesh_terms: D000328:Adult; D000886:Anthropometry; D001696:Biomechanical Phenomena; D015331:Cohort Studies; D005260:Female; D005413:Flatfoot / Q000175:diagnosis*; D005528:Foot / Q000033:anatomy & histology*; D018409:Foot Injuries / Q000517:prevention & control*; D006801:Humans; D008297:Male; D008889:Military Personnel; D011032:Podiatry / Q000379:methods; D012680:Sensitivity and Specificity; D013314:Stress, Mechanical; D016474:Weight-Bearing / Q000502:physiology