Legg-Calve-Perthes disease, often just called Perthes Disease, is a childhood condition where the blood supply to the hip joint is disrupted leading to degeneration of bone that makes up part of the joint (osteonecrosis). The part of the hip joint affected is the head of the femur. This is the ball part of the ball and socket hip joint.
Legg-Calve-Perthes occurs most commonly in children between the ages of 4 to 10 and is more common in boys than girls. The disease usually affects one hip but both hips can be affected. The first sign of Perthes is usually a painful limp that comes on for no apparent reason in a child.