The natural history of developmental dysplasia of the hip: sonographic findings in infants of 1-3 months of age.

The natural history of sonographic developmental dysplasia of the hip was determined in a population-based study in which 5170 infants were screened by ultrasound using Graf's method. Of the normal hips at the age of 1 month, 99.6% were still normal at the age of 3 months. Of the immature type IIa/IIa+ and type IIa- hips, if untreated, 95.3 and 84.4% had become normal, respectively. Of the infants with type IIc, D and III/IV hips at the age of 1 month 70, 58.3 and 90.9% were treated, respectively. This study shows that normal hips remain normal in nearly 100% of cases, but development to abnormality is possible. It shows also that most of the immature hips at the age of 1 month become normal without treatment. Although treatment seems to be indicated in the majority of sonographically abnormal hips, the occurrence of overtreatment could not be excluded in our study.