Udaya Bhaskara Rao and Benjamin Joseph. "The Influence of Footwear on the Prevalence of Flat Foot," The Journal of Bone and Joint Surgery, 74B(4), 1992, pp. 525-527.
In Europe and America flat foot is a common reason for attendance at a children's orthopaedic clinic, but in India children are seldom brought for treatment for flat foot. The few children who do attend with this complaint are from affluent urban families and they all wear shoes. In our clinic we have never seen a child from the farming community or from the family of a manual labourer who complained of flat foot.
The high concentration of flat foot among six-year-old children who wore shoes as compared with those who did not, implies that the critical age for development of the arch is before six years.
Our cross-sectional study suggests that shoe-wearing in early childhood is detrimental to the development of a normal or a high medial longitudinal arch. The susceptibility for flat foot among children who wear shoes is most evident if there is associated ligament laxity. We suggest that children should be encouraged to play unshod and that slippers and sandals are less harmful than closed-toe shoes.