Imaging of Legg–Calvé–Perthes Disease in Children

Legg–Calvé–Perthes (LCP) disease, sometimes shortened and referred to as Perthes disease, represents idiopathic necrosis of the proximal femoral epiphysis in skeletally immature children. It should be differentiated from avascular necrosis due to sickle cell disease, leukemia, and corticosteroid administration which can produce similar imaging findings. While it is generally accepted that an interruption in the blood supply to the immature femoral epiphysis is the underlying cause of the disease, and although several risk factors have been proposed, the ultimate etiology for this disruption in blood supply is unknown. Osteonecrosis of the immature femoral epiphysis can eventually cause fragmentation and deformity of the femoral head, including flattening of the femoral head (coxa plana), widening of the femoral neck (coxa magna), acetabular dysplasia with labral degeneration, and intra-articular or extra-articular CAM femoroacetabular impingement. Epiphyseal and acetabular deformity lead to decreased containment of the femoral head within the acetabulum and early hip osteoarthritis. The ultimate goal of treatment therefore is to prevent progressive femoral head deformity and maintain femoral head containment [1]. In most cases symptoms improve or resolve in childhood and prognosis is good in early adulthood, but increased incidence of hip osteoarthritis and need for hip replacement is noted in adulthood [2–6].