Goal

• To determine if variable stiffness shoes would reduce loading and pain in people with medial compartment knee osteoarthritis.
• To determine if variable stiffness shoes decrease the rate of cartilage thinning in people with medial compartment knee osteoarthritis.

Major Findings

• Variable-stiffness shoes reduce the knee adduction moment, an estimate of knee joint loading, in subjects with medial compartment knee osteoarthritis, and this reduction is sustained for a long-term time period of 12 months.
• Wearing the variable-stiffness shoe reduces pain and improves functionality after 6 and 12 months of wear.
• The reduction in knee adduction moment appears to be produced by a medial shift in the center of pressure at the foot during gait and a reduction in the frontal plane lever arm of the knee adduction moment.
• In a subject with an instrumented knee replacement, the variable stiffness shoe reduced the medial compartment joint contact force, and reductions in external knee adduction moment were indicative of reductions in in vivo medial compressive knee joint force.

Representative Publications

• An analysis of the mechanisms for reducing the knee adduction moment using a variable stiffness shoe in subjects with knee osteoarthritis
  Jenkyn TR, Erhart JC, Andriacchi TP. J Biomech. 2011 Apr; 44(7):1271-6.
• Changes in in vivo knee loading with a variable-stiffness intervention shoe correlate with changes in the knee adduction moment.
  Erhart JC, Dyrby CO, D'Lima DD, Colwell CW, Andriacchi TP. J Orthop Res. 2010 Dec; 28(12):1548-53.
• Changes in knee adduction moment, pain, and functionality with a variable-stiffness walking shoe after 6 months.
  Erhart JC, Mündermann A, Elspas B, Giori NJ, Andriacchi TP. J Orthop Res. 2010 Jul;28(7):873-9.
• A variable-stiffness shoe lowers the knee adduction moment in subjects with symptoms of medial compartment knee osteoarthritis.
  Erhart JC, Mündermann A, Elspas B, Giori NJ, Andriacchi TP. J Biomech. 2008 Aug 28;41(12):2720-5. Epub 2008 Aug 3.

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