The natural history of hip abnormalities detected by ultrasound in clinically normal newborns: a 6-8 year radiographic follow-up study of 93 children.

Ultrasound screening for hip dysplasia or dislocation has revealed a group of children with clinically normal hips, but with abnormal or suspicious ultrasound. During the 3-year period 1988-90, we found 170 children with this combination. We evaluated the natural history of these hips. 93 children were examined clinically and with standard radiography 6-8 years after birth. The center edge (CE) angle of Wiberg and migration percentage (MP) were measured on the radiographs. 87 children had not undergone any treatment, whereas treatment with an abduction orthosis had been initiated at approximately 4 months of age because of persisting dysplasia in 6 cases. All hips were radiographically normal at this follow-up. The mean CE value was 24 degrees (SD 6.5) and the mean MP was 13% (SD 5.2). 73 children had no complaints in their lower extremities, whereas 12 had intoeing gait, 1 had outtoeing gait, 2 had hip or knee pain, and 5 had other complaints not relevant to hip dysplasia. We conclude that infants with sonographically abnormal or suspicious hips, but with normal clinical findings, do not need immediate treatment because spontaneous resolution occurs in most of them. Postponement of treatment in the few with persistent dysplasia does not seem to affect the outcome.