The cause of Legg-Calvé-Perthes disease is unknown but has provoked considerable controversy. Previously, some authors thought that an inherited thrombophilia promoted thrombotic venous occlusion in the femoral vein, causing bone death in the femoral head and ultimately leading to Legg-Calvé-Perthes disease. More recent studies have not found an inherited hypercoagulability or a deficiency in protein C activity, however, indicating that inherited thrombophilia is not associated with the osteonecrosis of Legg-Calvé-Perthes disease. Although research continues, it seems that coagulation disorders are not conclusive etiologic factors in Legg-Calvé-Perthes disease. As noted by Hosalkar and Mulpuri, even after 100 years the etiology of Legg-Calvé-Perthes disease remains unclear and its treatment is still controversial.
