The effect of laterally wedged shoes on the loading of the medial knee compartment-in vivo measurements with instrumented knee implants.

A conventional method to unload the medial compartment of patients with gonarthrosis and thus to achieve pain reduction is the use of laterally wedged shoes. Our aim was to measure in vivo their effect on medial compartment loads using instrumented knee implants. Medial tibio-femoral contact forces were measured in six subjects with instrumented knee implants during walking with the following shoes: without wedge, with 5 and 10 mm wedges under the lateral sole, and with a laterally wedged insole (5 mm). Measurements were repeated with the shoes in combination with an ankle-stabilizing orthosis. Without orthosis, peak medial forces were reduced by only 1-4% on average. With orthosis, the average reduction was 2-7%. Highest reductions were generally observed with the 10 mm wedge, followed by the 5 mm wedge, and the 5 mm insole. Individual force reductions reached up to 15%. Medial force reductions while walking with wedged shoes were generally small. Due to high inter-individual differences, it seems that some patients might benefit from lateral wedges, whereas others might not. Further analyses of the individual kinematics will show which factors are most decisive for the reduction of medial compartment load.