Flatfeet involve a collapse of the medial longitudinal arch, hindfoot valgus, and forefoot abduction. Flexible flatfoot is the most common type and can often be corrected with physiotherapy or orthotics. While some individuals remain asymptomatic, others develop symptoms for reasons that are not fully understood. This cross-sectional study compared plantar pressure distributions in 16 adults with asymptomatic and 16 with symptomatic flexible flatfeet (FPI-6 > 6; navicular drop > 5 mm), using a resistive-sensor-equipped pressure plate during walking and heel-strike running. During walking, symptomatic participants showed significantly higher total and peak forces at metatarsal 5 (p ≤ 0.003), and the midfoot (p ≤ 0.02146). The medial heel had significantly lower peak force (p = 0.00147), and metatarsal 4 showed higher peak force (p = 0.02539). Force ratios indicated a more lateralized pressure distribution in the symptomatic group. During heel-strike running, the symptomatic group exhibited higher total and peak forces at the fifth metatarsal, the midfoot, and the first metatarsal, with shorter time to peak force in the midfoot and the medial part of the heel. No significant ratio differences were found during running. Symptomatic individuals adopted a lateralized pressure distribution pattern, contrasting the traditional expectation of medial overload in flatfoot conditions.
Haelewijn et al. (Thu,) studied this question.