Absence of congenital prethrombotic disorders in children with Legg-Perthes disease.

Resistance to activated protein C (RPCA) and other congenital prethrombotic disorders have been recently reported to be strongly associated with Legg-Perthes disease. RPCA and deficiencies of protein C, protein S, and antithrombin III were sought in 22 children with Legg-Perthes disease. Detection of the factor V Leiden mutation was found in children with RPCA. Twenty-two healthy children paired by age and sex served as controls. The prevalence of congenital prethrombotic disorders was not found to differ significantly among patients with Legg-Perthes disease and among control subjects. Only one patient had RPCA; this patient was heterozygous for the factor V Leiden mutation. Twenty patients and all the control subjects had entirely normal coagulation results. The authors conclude that unless more data become available, RPCA and deficiencies of protein C, protein S, and antithrombin III should not be considered associated with Legg-Perthes disease.