title: Foot type biomechanics part 1: structure and function of the asymptomatic foot.
abstract: BACKGROUND
  Differences in foot structure are thought to be associated with differences in foot function during movement. Many foot pathologies are of a biomechanical nature and often associated with foot type. Fundamental to the understanding of foot pathomechanics is the question: do different foot types have distinctly different structure and function?
  
  
  OBJECTIVE
  To determine if objective measures of foot structure and function differ between planus, rectus and cavus foot types in asymptomatic individuals.
  
  
  METHODS
  Sixty-one asymptomatic healthy adults between 18 and 77 years old, that had the same foot type bilaterally (44 planus feet, 54 rectus feet, and 24 cavus feet), were recruited. Structural and functional measurements were taken using custom equipment, an emed-x plantar pressure measuring device, a GaitMat II gait pattern measurement system, and a goniometer. Generalized Estimation Equation modeling was employed to determine if each dependent variable of foot structure and function was significantly different across foot type while accounting for potential dependencies between sides. Post hoc testing was performed to assess pair wise comparisons.
  
  
  RESULTS
  Several measures of foot structure (malleolar valgus index and arch height index) were significantly different between foot types. Gait pattern parameters were invariant across foot types. Peak pressure, maximum force, pressure-time-integral, force-time-integral and contact area were significantly different in several medial forefoot and arch locations between foot types. Planus feet exhibited significantly different center of pressure excursion indices compared to rectus and cavus feet.
  
  
  CONCLUSIONS
  Planus, rectus and cavus feet exhibited significantly different measures of foot structure and function.
authors.affiliation: Leon Root M.D. Motion Analysis Laboratory, Hospital for Special Surgery, 535 East 70th Street, New York, NY 10021, United States. HillstromH@Hss.edu
authors.forename: Howard J
authors.initials: HJ
authors.lastname: Hillstrom
authors.forename: Jinsup
authors.initials: J
authors.lastname: Song
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Kraszewski
authors.forename: Jocelyn F
authors.initials: JF
authors.lastname: Hafer
authors.forename: Rajshree
authors.initials: R
authors.lastname: Mootanah
authors.forename: Alyssa B
authors.initials: AB
authors.lastname: Dufour
authors.forename: Betty Shingpui
authors.initials: BS
authors.lastname: Chow
authors.forename: Jonathan T
authors.initials: JT
authors.lastname: Deland
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000843:Ankle Joint / Q000033:anatomy & histology / Q000502:physiology; D001696:Biomechanical Phenomena; D005260:Female; D005528:Foot / Q000033:anatomy & histology / Q000502:physiology*; D005530:Foot Deformities / Q000503:physiopathology*; D005684:Gait / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011312:Pressure; D011403:Pronation / Q000502:physiology; D013484:Supination / Q000502:physiology; D016474:Weight-Bearing / Q000502:physiology; D055815:Young Adult