Perthes disease

Perthes disease (synonyms: Calvé-Legg-Perthes disease, coxa plana ) is the most common and severe avascular bone necrosis.

The disease was described independently in 1910 by: Georg Perthes (German), Jacques Calvé (Fr.) and Arthur T. Legg (USA).

Idiopathic disease of the hip joint caused by impaired blood supply to the proximal epiphysis of the femur,  The ossification center of the femoral head succumbs to necrosis, is resorbed and gradually rebuilt into living bone. The result can be a fully functional hip joint or various deformities leading to the development of early osteoarthritis. It mainly affects (4x more often  ) boys aged 3–8 years, in 10% it is bilateral.

Etiopathogenesis
Transient disorder of the vascular supply of the head, thinning of its structure, subchondral fracture, gradual fragmentation of the necrotic epiphysis and subsequent remodeling.

The triggering factor of ischemia of unknown cause and duration. It leads to the development of avascular necrosis of the proximal epiphysis of the femur (more and more importance is attached to discrete forms of coagulopathies with the participation of proteins C and S and hypofibrinolysis ). There is an attenuation of enchondral ossification. The superficial cartilaginous part of the epiphysis continues to grow. In the next phase, the vascular supply and new bone formation gradually occur ( condensation stage ).

As a result of loading the limb, subchondral fractures appear (disrupting vascularization and prolonging the stage of necrosis). Further revascularization takes a long time ( stage of gradual remodeling ). The head of the femur is gradually formed depending on its relationship to the acetabulum and the degree of load.