CONTRADICTION OF THE CONGENITAL DYSPLASIA-PREDISLOCATION HYPOTHESIS OF CONGENITAL DISLOCATION OF THE HIP THROUGH A STUDY OF THE NORMAL VARIATION IN ACETABULAR ANGLES AT SUCCESSIVE PERIODS IN INFANCY

摘要

The acetabular angles were measured radiographically at birth in 627 unselected infants, of whom 551 were re-examined at 6 months, and 527 at 12 months of age. At birth there was a wide variation in the size of the angles. In the different categories, the mean values varied between 29 and 25 degrees; the two-standard-deviation ranges were 39 to 20 and 34 to 15 degrees, respectively. Clinical examination of the hips in a similar neonatal group of 666 infants. which was made up largely of the group examined radiologically, disclosed a high incidence of extra and asymmetrical skin folds in the thighs, and great uncertainty in the determination of limitation of abduction. Abduction was unequal on the 2 sides in 4 per cent of all newborns.At 6 months of age the angles showed marked reduction in size compared with the neonatal values. At 12 months of age the angles were slightly reduced in comparison with those at 6 months.The angles in white and Negro infants are approximately equal in size at birth, but in the same infants, the angles were slightly larger in Negroes at 6 and 12 months of age; notwithstanding the fact that congenital dislocation of the hips is virtually nonexistent in Negroes.