Nationwide Epidemiological and Demographic Evolution of Legg-Calvé-Perthes Disease: A 10-Year Analysis.

Background: Legg-Calvé-Perthes disease (LCPD) classically affects children aged 2-14 years. However, there is considerable variability in reported incidence, and larger-scale nationally representative age data in the United States are lacking. Some investigators have also suggested that the age at presentation may be trending younger in recent years. Therefore, the purpose of this study was to explore temporal trends in the epidemiology and demographic characteristics of LCPD and determine whether the age of children presenting with LCPD is changing. Methods: A retrospective review of all patients under 15 years of age diagnosed with LCPD between January 1, 2015, and December 31, 2024, was conducted at a single large tertiary care center and using the TriNetX US Research network. Geographic and demographic information, including age, sex, race, and ethnicity, was collected. Incident cases were calculated per 100,000 children within the specified period. Results: A total of 3,495 children (330 regional and 3,162 nationwide) were diagnosed with LCPD in our 10-year period (average age: 7.7 ± 3.2 years [regional], 7.4 ± 3.4 years [nationwide]). Between both cohorts, males (78.3%, 82.9%) represented a significantly larger proportion than females (20.6%, 17.1%). The average incidence rate (IR) was 7.82 per 100,000 children at our center and 6.75 per 100,000 nationwide. Children aged 5-9 years represented the most common group of new diagnoses for all but 1 year across both cohorts. The overall disease incidence significantly decreased over time both regionally and nationally ( Conclusions: In this large US study on the epidemiology of LCPD, we demonstrate both regional and nationwide IRs within a narrower range than previously described (∼7/100,000). The LCPD IR has significantly decreased over time, with the most prominent decrease seen in older children. We did not observe a significant change in the age of presentation over the last decade. Key Concepts: (1)The incidence of Legg-Calvé-Perthes disease (LCPD) in the United States has decreased over time, with a contemporary nationwide incidence rate of approximately 7 cases per 100,000 children.(2)Children aged 5-9 years remain the most commonly affected group, while new diagnoses among older children (10-14 years) have decreased and appear to be contributing to the overall declining disease incidence.(3)Despite these epidemiological shifts, average age at LCPD diagnosis has remained stable. Level of Evidence: III, Retrospective cohort study.