Osteochondrosis of the femoral head

Legg-Calvé-Perthes disease, also known as Perthes disease or flat hip, is a self-limiting, avascular disease characterized by partial or complete necrosis of the femoral head epiphysis due to impaired blood supply to the femoral head from various causes. After healing, the femoral head often presents with a flattened deformity, hence the name "flat hip."