[Analysis of acetabular changes in Morbus Perthes disease with radiomorphometry].

AIM: Decreases in depth and irregularity are typical changes of the acetabulum in patients with Perthes disease and develop secondary to the femoral head involvement. Optimal timing of therapy plays an important role to prevent these secondary changes. The present study investigates the influence of the amount of femoral head involvement and the patients' age on the acetabulum and the outcome.

METHODS

66 patients with 76 affected hip joints were included in the study. 20 hips had a conservative therapy, 22 an operative therapy (IVO). 34 hip joints underwent a conservative therapy at first, followed by an operative intervention. The radiomorphometric analyses at the time of diagnosis, pre- and postoperatively and at follow-up were performed with epiphyseal ratio, acetabular ratio and acetabulum-head ratio. At the time of diagnosis the patients were classified with the Catterall classification, at follow-up with Mose classification.

RESULTS

Independent from therapy there was a correlation of the parameters with Catterall classification over the whole course, i.e., the higher the Catterall group the worse the parameter at the time of diagnosis as well as at follow-up. Operatively treated patients with Catterall IV tended towards a worse result of the epiphyseal ratio whereas they achieved better results in the other parameters compared to conservatively treated patients. Catteral I and II patients achieved good results.

CONCLUSION

Operative treatment of the higher Catterall groups seems to be more effective than conservative therapy. Secondary changes of the acetabulum develop in proportion to the amount of femoral head involvement.