title: The Effect of an In-shoe Orthotic Heel Lift on Loading of the Achilles Tendon During Shod Walking.
abstract: METHODS
  Controlled laboratory study.
  
  
  BACKGROUND
  Orthotic heel lifts are thought to lower tension in the Achilles tendon, but evidence for this effect is equivocal.
  
  
  OBJECTIVE
  To investigate the effect of a 12-mm, in-shoe orthotic heel lift on Achilles tendon loading during shod walking using transmission-mode ultrasonography.
  
  
  METHODS
  The propagation speed of ultrasound, which is governed by the elastic modulus and density of tendon and proportional to the tensile load to which it is exposed, was measured in the right Achilles tendon of 12 recreationally active men during shod treadmill walking at matched speeds (3.4 ± 0.7 km/h), with and without addition of a heel lift. Vertical ground reaction force and spatiotemporal gait parameters were simultaneously recorded. Data were acquired at 100 Hz during 10 seconds of steady-state walking. Statistical comparisons were made using paired t tests (α = .05).
  
  
  RESULTS
  Ultrasound transmission speed in the Achilles tendon was characterized by 2 maxima (P1, P2) and minima (M1, M2) during walking. Addition of a heel lift to footwear resulted in a 2% increase and 2% decrease in the first vertical ground reaction force peak and the local minimum, respectively (P<.05). Ultrasonic velocity in the Achilles tendon (P1, P2, M2) was significantly lower with the addition of an orthotic heel lift (P<.05).
  
  
  CONCLUSIONS
  Peak ultrasound transmission speed in the Achilles tendon was lower with the addition of a 12-mm orthotic heel lift, indicating that the heel lift reduced tensile load in the Achilles tendon, thereby counteracting the effect of footwear observed in previous studies. These findings support the addition of orthotic heel lifts to footwear in the rehabilitation of Achilles tendon disorders where management aims to lower tension within the tendon.
authors.forename: Mathias
authors.initials: M
authors.lastname: Wulf
authors.forename: Scott C
authors.initials: SC
authors.lastname: Wearing
authors.forename: Sue L
authors.initials: SL
authors.lastname: Hooper
authors.forename: Simon
authors.initials: S
authors.lastname: Bartold
authors.forename: Lloyd
authors.initials: L
authors.lastname: Reed
authors.forename: Torsten
authors.initials: T
authors.lastname: Brauner
mesh_terms: D000125:Achilles Tendon / Q000000981:diagnostic imaging / Q000502:physiology*; D000328:Adult; D006365:Heel; D006801:Humans; D008297:Male; D008875:Middle Aged; D009989:Orthotic Devices; D012775:Shoes; D014463:Ultrasonography; D016138:Walking / Q000502:physiology*; D016474:Weight-Bearing; D055815:Young Adult
keywords: footwear; orthoses; quantitative ultrasound; soft tissue; speed of sound