Normal ranges of hip motion in infants six weeks, three months and six months of age.

Flexion contracture, internal rotation and external rotation of the hip were reported in 40 infants at 6 weeks and 3 months and in an independent sample of 40 infants at 6 months of age. Population means and normal ranges of motion were determined for use in the evaluation of hip problems and their treatment. A mean hip flexion contracture of 19 degrees was present at 6 weeks of age, decreasing to 7 degrees by three months, but still persisting at 6 months suggesting that forceful extension of the hip in infants may be contraindicated. Hip flexion contracture decreased in every child from 6 weeks to three months. In all cases, external rotation was greater than internal rotation. Internal rotation greater than external rotation before the age of 6 months appears contrary to normal development. There was a significant correlation between the changes in hip flexion contracture and internal rotation from 6 weeks to 3 months. An interesting extension of this study would be a longitudinal follow-up of infants beyond 6 months of age to further define these developmental trends.