Evolutionary regularity of acetabular dysplasia after reduction of developmental dislocation of the hip.

OBJECTIVE

To observe the developmental changes of the acetabulum after reduction of developmental dislocation of the hip and require evolutionary regularity of acetabular dysplasia.

METHODS

A follow-up in an average of 7.4 years was carried out in 117 patients (161 hips) with developmental dislocation of the hip after reduction. By the series of X-ray films, acetabular index, acetabular-head index, Sharp's angle, ACM angle (Idelberger's angle) and anteversion were observed. At the same time, centre-head distance discrepancy was measured.

RESULTS

Acetabular index returned to normal gradually as the time went by and significantly within one year after the reduction of developmental dislocation of the hip. The process of recovery was nearly stable three years later. Acetabular index in the dysplasia group was above 39 degrees before reduction and decreased slowly after the reduction. However, it was still up to 30 degrees after 3 years observation. The value of centre-head distance discrepancy decreased gradually as the years went by after reduction.

CONCLUSIONS

If acetabular index before reduction is above 39 degrees and is still up to 30 degrees three years after reduction, acetabular dysplasia can be diagnosed.