Backround: The etiology of Legg-Calvé-Perthes disease (LCPD) is incompletely understood. Previous studies suggest associations with coagulation problems, anatomical abnormalities in the femoral head blood supply and risks for cardiovascular disease. Therefore, we hypothesized that patients with LCPD might have a higher risk of cardiovascular diseases and diseases of blood and blood-forming organs.

Methods: 3,141 patients with LCPD aged 2–15 years, diagnosed between 1965 and 2005 were identified using the Swedish inpatient register. 15,595 individuals without LCPD were randomly selected from among the Swedish general population, matched by year of birth, age, sex, and region of residence. Cox proportional hazard regression, adjusted for socioeconomic index, was used to estimate the relative risks. The patients were also compared with their same-sex siblings.

Results: Patients with LCPD had a hazard ratio (HR) of 1.70 (95% CI 1.39–2.09) for cardiovascular disease compared with individuals without LCPD. The point estimate was slightly higher among those older than 30 at follow-up (HR=2.10, 95% CI: 1.52–2.91). There were statistically significant higher risks for diseases of blood and blood-forming organs (1.41, 1.07–1.86), which were more pronounced among those older than 30 years at follow-up (2.70. 1.50–4.84). Patients had also statistically significant higher risks for hypertensive disease (2.97, 1.87–4.72), and nutritional anemia (2.92, 1.58–5.40). When siblings were used as the comparison group, the results were consistent for cardiovascular disease.

Conclusion: The results are consistent with the hypothesis that an insufficient blood supply to the femoral head due to vascular pathology and other causes are involved in the etiology of LCPD.