title: Increased in-shoe lateral plantar pressures with chronic ankle instability.
abstract: BACKGROUND
  Previous plantar pressure research found increased loads and slower loading response on the lateral aspect of the foot during gait with chronic ankle instability compared to healthy controls. The studies had subjects walking barefoot over a pressure mat and results have not been confirmed with an in-shoe plantar pressure system. Our purpose was to report in-shoe plantar pressure measures for chronic ankle instability subjects compared to healthy controls.
  
  
  METHODS
  Forty-nine subjects volunteered (25 healthy controls, 24 chronic ankle instability) for this case-control study. Subjects jogged continuously on a treadmill at 2.68 m/s (6.0 mph) while three trials of ten consecutive steps were recorded. Peak pressure, time-to-peak pressure, pressure-time integral, maximum force, time-to-maximum force, and force-time integral were assessed in nine regions of the foot with the Pedar-x in-shoe plantar pressure system (Novel, Munich, Germany).
  
  
  RESULTS
  Chronic ankle instability subjects demonstrated a slower loading response in the lateral rearfoot indicated by a longer time-to-peak pressure (16.5% +/- 10.1, p = 0.001) and time-to-maximum force (16.8% +/- 11.3, p = 0.001) compared to controls (6.5% +/- 3.7 and 6.6% +/- 5.5, respectively). In the lateral midfoot, ankle instability subjects demonstrated significantly greater maximum force (318.8 N +/- 174.5, p = 0.008) and peak pressure (211.4 kPa +/- 57.7, p = 0.008) compared to controls (191.6 N +/- 74.5 and 161.3 kPa +/- 54.7). Additionally, ankle instability subjects demonstrated significantly higher force-time integral (44.1 N/s +/- 27.3, p = 0.005) and pressure-time integral (35.0 kPa/s +/- 12.0, p = 0.005) compared to controls (23.3 N/s +/- 10.9 and 24.5 kPa/s +/- 9.5). In the lateral forefoot, ankle instability subjects demonstrated significantly greater maximum force (239.9N +/- 81.2, p = 0.004), force-time integral (37.0 N/s +/- 14.9, p = 0.003), and time-to-peak pressure (51.1% +/- 10.9, p = 0.007) compared to controls (170.6 N +/- 49.3, 24.3 N/s +/- 7.2 and 43.8% +/- 4.3).
  
  
  CONCLUSIONS
  Using an in-shoe plantar pressure system, chronic ankle instability subjects had greater plantar pressures and forces in the lateral foot compared to controls during jogging.
  
  
  CONCLUSIONS
  These findings may have implications in the etiology and treatment of chronic ankle instability.
authors.affiliation: University of Virginia, 2270 Ivy Road, Box 800232, Charlottesville, VA 22903, USA.
authors.forename: Heather
authors.initials: H
authors.lastname: Schmidt
authors.forename: Lindsay D
authors.initials: LD
authors.lastname: Sauer
authors.forename: Sae Yong
authors.initials: SY
authors.lastname: Lee
authors.forename: Susan
authors.initials: S
authors.lastname: Saliba
authors.forename: Jay
authors.initials: J
authors.lastname: Hertel
mesh_terms: D000328:Adult; D000843:Ankle Joint / Q000503:physiopathology*; D002908:Chronic Disease; D005260:Female; D005528:Foot / Q000503:physiopathology*; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology*; D008297:Male; D009068:Movement / Q000502:physiology; D012775:Shoes; D055815:Young Adult