Hypermobile flatfoot in children. Comprehension, evaluation, and treatment.

Comprehension of the hypermobile flatfoot deformity depends on an understanding of the three structural deformities of the foot associated with the condition: (1) abduction of the forefoot relative to the weight-bearing line; (2) supination of the forefoot; and (3) heel valgus. Evaluation of the hypermobile flatfoot deformity is by clinical examination to determine the position of the foot with the talonavicular joint in the congruous position: position and motion of these components are determined from this starting point. A standing lateral talometatarsal angle is used to evaluate the deformity roentgenographically. Treatment in the newborn or infant is by casting, inflare shoes, and Denis-Browne night splints for severe deformities. Support with shoes is used in children one to three years of age. Complete clinical and roentgenographic examinations should be performed when the child is three years of age. If a painful or grossly abnormal flatfoot deformity is present, custom-molded inserts are used during the period of growth. After growth has ceased flatfoot is treated only if it is painful or produces impairment. Treatment is then by shoes, inserts, or orthotics. Surgery is considered only if these devices do not alleviate the difficulty and the patient is incapacitated. Surgical procedures are designed to correct the structural abnormalities without fusing joints in an attempt to restore the normal position and motion of the components of the foot.