Effects of Shoe Lifespan on Gait Kinetics in Women With Knee Genu Varum and Healthy Peers

Knee genu varum is one of the lower limb abnormalities associated with biomechanical changes in lower limbs. The present study aims to compare the effects of shoe lifespan on ground reaction force (GRF) components in women with knee genu varum and healthy peers during running.

The is randomized clinical trial. Participants were 15 female college students with knee genu varum and 15 healthy peers. A new pair of sport shoes was given to each participant during to wear them for six months. Then, they were asked to run at a preferred speed in three trials with the new shoes (pre-test phase) and three trials with the used shoes (post-test phase) in a path where a force plate was installed. Statistical analysis was conducted by using repeated measures ANOVA. All analyses were done in SPSS v. 23 software. The significance level was set at 0.05.

 The results indicated the significant main (group) effect of shoes on peak anterior-posterior GRF during heel contact and on the anterior-posterior impulse (P<0.018, d>0.8). The values of these variables in the genu varum group were significantly higher than in the healthy group. Moreover, findings showed the significant main effects of shoes on the time to reach the peak GRF during heel strike and on the loading rate (P< 0.02, d > 0.9). The time to reach the peak GRF during heel strike with the used shoes was shorter than with the new shoes (P= 0.015, d=0.9), while the vertical loading rate during running with the worn shoes was greater than with the new shoes (P=0.019, d=0.9).

 Running with shoes having a lifespan >6 months is a risk factor for women with knee genu varum.