Purpose: The aim of our study was to assess the influence of asymptomatic flatfoot on the kinetic parameters of the lower limb during gait.
Methods: Individuals of both sexes were studied: 15 women [age 25 ± 5 years] and 19 men [age 25 ± 4 years] with bilateral asymptomatic flatfoot, as well as 16 women [age 26±4 years] and 14 men [age 24 ± 3 years] with normal feet on both sides. A threedimensional VICON motion analysis system coupled with KISTLER dynamometric platforms was used to perform kinetic gait analysis.
Results: Women with flatfoot showed significantly lower maximal relative moments in the ankle in the sagittal plane ( p < 0.05) and significantly lower maximal relative moments in the knee in the sagittal plane in the Terminal Stance ( p < 0.001). In men, a significant difference was found in terms of hip rotation moment in the transverse plane in the Mid Stance ( p < 0.01): men with normal feet showed moments of external rotation, while men with flatfoot generated internal rotational moments. Moreover, men with flatfoot showed significantly lower ( p < 0.01) maximal relative moments in the knee in the transverse plane in the Mid Stance.
Conclusions: Women with flatfoot have a weakened lower limb propulsion mechanism, whereas, in men with flatfoot, there is a change in the mechanics of the lower limb in the transverse plane. Our findings cast some doubt on flatfoot as a putative risk factor for stress injuries and degenerative changes in lower-limb structures, and suggest that gender differentiation should be taken into account in the analysis and therapy of flatfoot.