[Comparison of the prognostic value of the Catterall and Herring classification in patients with Perthes disease].

Question: Investigation of the predictive value of the Catterall- as compared to the Herring-classification in patients with Perthes disease.
Method: A radiological follow-up study including 53 patients with a total of 59 affected hips was carried out. In the initial diagnosis the Catterall-, Waldenström- and Herring-stages were assessed. The epiphyseal ratio, the head-neck ratio and the lateral subluxation were measured and compared at the time of diagnosis, fragmentation stage and in a follow-up examination, which was carried out 4, 9 years after diagnosis on the average. The results of the follow-up examination were assessed using the Mose-classification and compared as well. In addition the two classifications were compared as to the necessity of an upgrading.
Results: Both classifications yielded similar descriptions of the radiomorphometric course. There was a good correlation between the results of Herring A and Catterall I, Herring B and Catterall II and III and Herring C and Catterall IV. Upgradings were necessary in the Herring- and the Catterall-classification in 21 cases, and 18 cases, respectively.
Conclusion: The predictive values of both classifications are comparable.