External rotation contracture of the extended hip. A common phenomenon of infancy obscuring femoral neck anteversion and the most frequent cause of out-toeing gait in children.

External rotation contracture of the extended hip is common in young infants, decreasing progressively with growth so that it appears to be present in less than 5 per cent of the children over age 18 months. Persistence of the external rotation contracture was the main cause of toeing-out gait in this study. Femoral neck anteversion, as a cause of internal rotation posturing of the limb, does not become clinically recognizable until complete resolution of the external rotation contracture of the hip has occurred, that is, usually after 18 months of age. Femoral neck retroversion was not present clinically in any of the patients examined, and so appears to be quite rare. Approximately 80 per cent of children under 18 months of age who toe-in have internal tibiofibular torsion; most of these also have significant talar neck adductus! Approximately 70 per cent of children over age 2 years who toe-in have excess femoral neck anteversion as the cause. Approximately 75 per cent of the children with metatarsus adductus deformity have coexistent internal tibial torsion and talar neck adductus; only 25 per cent of children with internal tibial torsion have coexistent metatarsus adductus deformity. Physiologic genu varum usually occurs prior to 2 years of age and physiologic genus valgum usually occurs after 2 years of age.