We investigated the prognosis of untreated 42 flat feet
The results were as follow:
1) Untreated infantile pronated feet; pronation deformity of the heel tended to decrease to a certain degree as infant grew older, but the lowering of medial longitudinal arch, mainly due to the naviculo-cuneiform sag, remained.
2) Prognosis of the congenital calcaneus feet revealed to be good. We usually need no treatment of this deformity except the case with strong contracture of dorsiflexsors.
3) As generally accepted, prognosis of the congenital convex pes valgus is miserable. So this deformity must be diagnosed and treated as possible as early. We could not follow the prognosis of the congenital calcaneo-valgus foot, but we think we can not expect the spontanous correction of this deformity from our clinical experience.