Foot-ground interaction during upright standing in children with Down syndrome

This study aimed to quantitatively characterize the main foot-ground contact parameters during static upright standing and to assess foot evolution with increasing age in young individuals affected by Down syndrome (DS). To this end, 99 children with DS of mean age 9.7 (1.7) were tested using a pressure sensitive mat, and the raw data were processed to extract information about overall and rearfoot, midfoot and forefoot contact area, Arch Index (AI) and average contact pressure. The values obtained were then compared with those calculated from a sample of age- and gender-matched participants (control group, CG). Children with DS exhibited larger midfoot and reduced forefoot contact areas with respect to CG participants (+53% and -35% respectively, p<0.001), increased AI values (DS 0.31, CG 0.20, p<0.001) and increased average contact pressures in the midfoot and forefoot. The overall foot development for the two groups followed a similar trend, although in individuals with DS a curve that relates increases in midfoot contact area with age is characterized by a steeper gradient, and the forefoot contact area appeared systematically smaller regardless of age. The large prevalence of the flatfoot type in children with DS (which is known to be originated by hypotonia and ligamentous laxity) associated with the presence of higher average contact pressure in midfoot and forefoot justify the need for careful podiatric surveillance throughout childhood to reduce balance and gait impairment which are likely to affect untreated subjects when they reach adulthood.