Hip rotation and in-toeing gait. A study of normal subjects from four years until adult age.

In a selected population, from four years old up to adult age, the function of 1522 hips of 761 apparently normal subjects of both genders were studied to define: (1) the lower and upper limits of normal hip rotation; and (2) the frequency of in-toeing gait related to age and gender. Internal and external rotation were measured with the subject lying prone with flexed knees. Presence of in-toeing gait was noted. A significant reduction of internal rotation with age was found in both females and males. In all age groups, females had significantly higher range of internal rotation than males. External rotation did not show the same age and gender dependency. Sixteen percent of all subjects had an in-toeing gait. The frequency decreased from 30% in the four-year-old group to 4% in adults. The subjects with in-toeing had a significantly increased internal rotation and decreased external rotation.