Development of acetabulum after closed reduction in developmental hip dysplasia.

The radiographic study of acetabulum development after closed reduction of 87 congenitally dislocated hips in 64 patients who were treated between 1980 and 1990 was conducted retrospectively. An average patient's age at the moment of closed hip reduction was 16 months (range between 6 to 24 months). On the average, patients were 16 months old (range between 6 to 24 months) at the moment of closed hip reduction. Development of bony acetabulum was followed for 8 years by measuring the AC angle. According to the age at the moment of closed reduction patients were sorted into three groups, the first group from 6 months to 12 months old (39 hips), the second group from 12 to 24 months old (28 hips) and the third group from 24 to 36 months old (20 hips). At the beginning of the treatment mean values of the AC angle in the first group were 37.2 degrees +/- 3.31 degrees; in the second group 39.7 degrees +/- 3.2 degrees; and in the third group 43.8 degrees +/- 2.7 degrees. The final values of the AC angle in the first group were 14.7 degrees +/- 3.21 degrees, in the second group 21 degrees +/- 3.02 degrees; and in the third group 24 degrees +/- 3.76 degrees. Normally and mildly dysplastic hips were achieved in 80.5% treated hips, while in 19.5% treated hips medium and serious dysplasia retarded. The acetabulum development in dysplastic hip after retained stable concentric reduction was the same as in the normal hip. The operative reconstruction of acetabulum should not be done before the third year of life.