Background: The Japanese Pediatric Orthopaedic Association created a project team in 2000 to research pediatric orthopedic disease through a multicenter study. The aim of this study was to collect epidemiological data on Legg-Calvé-Perthes disease (LCPD) in Japan.
Methods: The following data were collected by a survey: age, sex, date of diagnosis, family history, sports history, affected sites, symptoms, location of pain, Catterall classification, Herring classification, date of treatment initiation, treatment methods, bracing period, and Stulberg classification.
Results: A total of 711 patients with 766 affected hips were seen from January 1, 1993 to December 31, 1995. The average annual incidence of LCPD was 0.9/100 000. The average age at diagnosis was 7 years 1 month (2.3-14.3 years). The male/female ratio of the study population was 6.3 : 1.0. The affected-side ratio (right hip/left hip/both hips) was 5.1 : 6.8 : 1.0. Both hips were affected in 7.7% of this series. By the Stulberg classification there were 211 (69.4%) type I and II patients (of 304 total patients). Six treatment methods for unilateral LCPD were compared, and there were no significant differences in outcome among the six groups. The ordinal logistic regression analysis showed that the Herring classification, age at the time of diagnosis, and the affected side (for unilateral LCPD) were significant predictors. The ordinal logistic regression analysis also showed that operative treatment had a better outcome than conservative treatment, with an odds ratio of 1.872.
Conclusions: Many containment methods for LCPD have been performed in Japan, and the optimal treatment method for LCPD was not determined in this study. The overall outcome, however, was not worse than that in worldwide reports.