title: Biomechanical and clinical factors related to stage I posterior tibial tendon dysfunction.
abstract: METHODS
  Case control.
  
  
  OBJECTIVE
  To investigate differences in arch height, ankle muscle strength, and biomechanical factors in individuals with stage I posterior tibial tendon dysfunction (PTTD) in comparison to healthy individuals.
  
  
  BACKGROUND
  PTTD is a progressive condition, so early recognition and treatment are essential to help delay or reverse the progression. However, no previous studies have investigated stage I PTTD, and no single study has measured static anatomical structure, muscle strength, and gait mechanics in this population.
  
  
  METHODS
  Twelve individuals with stage I PTTD and 12 healthy, age- and gender-matched control subjects, who were engaged in running-related activities, participated in this study. Measurements of arch height index, maximum voluntary ankle invertor muscle strength, and 3-dimensional rearfoot and medial longitudinal arch kinematics during walking were obtained.
  
  
  RESULTS
  The runners with PTTD demonstrated significantly lower seated arch height index (P = .02) and greater (P = .03) and prolonged (P = .05) peak rearfoot eversion angle during gait, compared to the healthy runners. No differences were found in standing arch height index values (P = .28), arch rigidity index (P = .06), ankle invertor strength (P = .49), or peak medial longitudinal arch values (P = .49) between groups.
  
  
  CONCLUSIONS
  The increased foot pronation is hypothesized to place greater strain on the posterior tibialis muscle, which may partially explain the progressive nature of this condition.
authors.affiliation: Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Melissa
authors.initials: M
authors.lastname: Rabbito
authors.forename: Michael B
authors.initials: MB
authors.lastname: Pohl
authors.forename: Neil
authors.initials: N
authors.lastname: Humble
authors.forename: Reed
authors.initials: R
authors.lastname: Ferber
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D002170:Canada; D016022:Case-Control Studies; D005260:Female; D005413:Flatfoot / Q000503:physiopathology; D005684:Gait; D006801:Humans; D008297:Male; D037081:Posterior Tibial Tendon Dysfunction / Q000503:physiopathology*; D011403:Pronation / Q000502:physiology; D052256:Tendinopathy; D014481:United States; D055815:Young Adult