Are the feet of obese children fat or flat? Revisiting the debate

There is debate as to the effects of obesity on the developing feet of children. We aimed to determine whether the flatter foot structure characteristic of obese primary school-aged children was due to increased medial midfoot plantar fat pad thickness (fat feet) or due to structural lowering of the longitudinal arch (flat feet).

Participants were 75 obese children (8.3 ± 1.1 years, 26 boys, BMI 25.2 ± 3.6 kg m(-2)) and 75 age- and sex-matched non-obese children (8.3 ± 0.9 years, BMI 15.9 ± 1.4 kg m(-2)). Height, weight and foot dimensions were measured with standard instrumentation. Medial midfoot plantar fat pad thickness and internal arch height were quantified using ultrasonography.

Obese children had significantly greater medial midfoot fat pad thickness relative to the leaner children during both non-weight bearing (5.4 and 4.6 mm, respectively; P<0.001) and weight bearing (4.7 and 4.3 mm, respectively; P < 0.001). The obese children also displayed a lowered medial longitudinal arch height when compared to their leaner counterparts (23.5 and 24.5 mm, respectively; P = 0.006).

Obese children had significantly fatter and flatter feet compared to normal weight children. The functional and clinical relevance of the increased fatness and flatness values for the obese children remains unknown.