The predictive value of the development of the acetabular teardrop figure in developmental dysplasia of the hip.

We reviewed the radiographs of 72 hips, 47 with developmental dysplasia of the hip (DDH), and 25 normal hips, to determine the timing of the normal appearance of the acetabular teardrop figure and the value of teardrop development after reduction of the hip in predicting outcome. In normal hips, all children had a teardrop figure by age 18 months. In the 47 hips with DDH, no teardrop figure appeared until the hip was reduced. The DDH hips were divided into two groups based on the success of the initial reduction. By using statistical analysis, we found that the appearance of the acetabular teardrop within 6 months after reduction of the hip is strongly associated with a favorable long-term outcome. We believe that the appearance of the teardrop is the earliest radiographic sign that a stable, concentric reduction of the hip has been achieved.