title: Kinematic analysis of ankle stiffness in subjects with and without flat foot.
abstract: BACKGROUND
  Although the magnitude of ankle motion is influenced by joint congruence and ligament elasticity, there is a lack of understanding on ankle stiffness between subjects with and without flat foot.
  
  
  OBJECTIVE
  This study investigated a quantified ankle stiffness difference between subjects with and without flat foot.
  
  
  METHODS
  There were forty-five age- and gender-matched subjects who participated in the study. Each subject was seated upright with the tested foot held firmly onto a footplate that was attached to a torque sensor by the joint-driving device.
  
  
  RESULTS
  The flat foot group (mean ± standard deviation) demonstrated increased stiffness during ankle dorsiflexion (0.37 ± 0.16 for flat foot group, 0.28 ± 0.10 for control group; t=-2.11, p=0.04). However, there was no significant group difference during plantar flexion (0.35 ± 0.15 for flat foot group, 0.33 ± 0.07 for control group; t=0.64, p=0.06).
  
  
  CONCLUSIONS
  The results of this study indicated that the flat foot group demonstrated increased ankle stiffness during dorsiflexion regardless of demographic factors. This study highlights the need for kinematic analyses and joint stiffness measures during ankle dorsiflexion in subjects with flat foot.
authors.affiliation: Department of Physical Therapy, Panuska College of Professional Studies, The University of Scranton, 800 Linden St, Scranton, PA 18510, United States. Electronic address: drpsung@gmail.com.
authors.forename: Paul S
authors.initials: PS
authors.lastname: Sung
mesh_terms: D000328:Adult; D000368:Aged; D000843:Ankle Joint / Q000503:physiopathology*; D001696:Biomechanical Phenomena; D004548:Elasticity; D005260:Female; D005413:Flatfoot / Q000503:physiopathology*; D006801:Humans; D008023:Ligaments, Articular / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D016059:Range of Motion, Articular / Q000502:physiology*; D019415:Torque
keywords: Ankle joint; Dorsiflexion; Flat foot; Kinematics; Plantar flexion; Stiffness