title: The influence of arch supports on knee torques relevant to knee osteoarthritis.
abstract: OBJECTIVE
  Changes in footwear and foot orthotic devices have been shown to significantly alter knee joint torques thought to be relevant to the progression if not the development of knee osteoarthritis (OA) in the medial tibiofemoral compartment. The purpose of this study was to determine if commonly prescribed arch support cushions promote a medial force bias during gait similar to medial-wedged orthotics, thereby increasing knee varus torque during both walking and running.
  
  
  METHODS
  Twenty-two healthy, physically active young adults (age, 29.2 +/- 5.1 yr) were analyzed at their self-selected walking and running speeds in control shoes with and without arch support cushions. Three-dimensional motion capture data were collected in synchrony with ground reaction force (GRF) data collected from an instrumented treadmill. Peak external knee varus torque during walking and running were calculated through a full inverse dynamic model and compared.
  
  
  RESULTS
  Peak knee varus torque was statistically significantly increased by 6% (0.01 +/- 0.02 N.m.(kg.m)(-1)) in late stance during walking and by 4% (0.03 +/- 0.03 N.m.(kg.m)(-1)) during running with the addition of arch support cushions.
  
  
  CONCLUSIONS
  The addition of material under the medial aspect of the foot by way of a flexible arch support promotes a medial force bias during walking and running, significantly increasing knee varus torque. These findings suggest that discretion be employed with regard to the prescription of commonly available orthotic insoles like arch support cushions.
authors.affiliation: University of Virginia, Department of Physical Medicine and Rehabilitation, Charlottesville, VA 22908, USA. JRF5N@virginia.edu
authors.forename: Jason R
authors.initials: JR
authors.lastname: Franz
authors.forename: Jay
authors.initials: J
authors.lastname: Dicharry
authors.forename: Patrick O
authors.initials: PO
authors.lastname: Riley
authors.forename: Keith
authors.initials: K
authors.lastname: Jackson
authors.forename: Robert P
authors.initials: RP
authors.lastname: Wilder
authors.forename: D Casey
authors.initials: DC
authors.lastname: Kerrigan
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D005260:Female; D005528:Foot / Q000503:physiopathology; D005684:Gait; D006801:Humans; D008297:Male; D009989:Orthotic Devices; D020370:Osteoarthritis, Knee / Q000503:physiopathology* / Q000534:rehabilitation*; D012420:Running / Q000502:physiology; D012775:Shoes; D019415:Torque; D016896:Treatment Outcome; D016138:Walking / Q000502:physiology