Prognostic value of Catterall and Herring classification in Legg-Calvé-Perthes disease: follow-up to skeletal maturity of 32 patients.

To compare the prognostic value of the Catterall and Herring classification, 32 patients, treated without surgery for unilateral Perthes diseases, were reviewed and classified at skeletal maturity according to Stulberg. The Catterall classification had no significant prognostic correlation with the final outcome. Only some head at-risk signs, such as lateral epiphyseal calcification and epiphyseal subluxation >4 mm, were prognostic. The Herring lateral pillar was not predictive when it was considered alone, but it became prognostic when related to age at onset. Moreover, in group C of the Herring classification (lateral pillar <50%), the final outcome was better in children younger than 6 years. This last observation strengthens the opinion that age and related residual skeletal moulding are also of prognostic value in Perthes disease.