The effect of valgus bracing on the knee adduction moment during gait and running in male subjects with varus alignment

BACKGROUND: Increased mechanical load is one risk factor for osteoarthritis. One possible treatment for this disorder is the use of knee braces in order to redistribute joint loading, which may inhibit the progression of the disease. The hypothesis was: knee adduction moment can be reduced with the use of a dedicated knee orthosis, which applies an abduction moment at the knee.

METHODS: Sixteen healthy male subjects with varus alignment were analysed during walking and running while using an adjustable valgus orthosis. Peak knee adduction moments and knee adduction angular impulses were evaluated through inverse dynamics. Additionally, the abduction moment produced by the orthosis was measured in three different adjustments of valgus angulations (neutral, 4 degrees and 8 degrees valgus) using a strain gauge device.

FINDINGS: During walking, mean reductions of 25% and 36% in the knee adduction angular impulse were found between the conditions without orthosis and 4 degrees and between without orthosis and 8 degrees, respectively. For the running trials mean reductions of 18% and 23% were observed between these same conditions. The first and second peak knee adduction moments also decreased during walking with different orthosis adjustments (changes from 5% to 33%). During running, a significant reduction was observed only between the conditions without orthosis and 8 degrees valgus adjustments (change of 11%).

INTERPRETATION: The orthosis tested in this study was effective in reducing the knee adduction moments during walking and running. This reduction of knee adduction moments during locomotion should contribute to decelerate osteoarthritis progression.