Contracted valgus flat foot in the adolescent is frequently caused by tarsal synostosis or synchondrosis which are often not revealed in common radiographic views, and which may instead by clearly shown by CT scan. These synostoses are prevalently symptomatic during adolescence, when by ossifying they block the subtalar joint in valgus; they are less symptomatic between 20 and 40 years of age. Pain returns during the fifth decade due to the occurrence of secondary arthrosis of the nearby joints.