Legg-Calve-Perthes disease is a childhood condition that occurs when blood supply to the ball part (femoral head) of the hip joint is temporarily interrupted and the bone begins to die.
This weakened bone gradually breaks apart and can lose its round shape. The body eventually restores blood supply to the ball, and the ball heals. But if the ball is no longer round after it heals, it can cause pain and stiffness. The complete process of bone death, fracture and renewal can take several years.
To keep the ball part of the joint as round as possible, doctors use a variety of treatments that keep it snug in the socket portion of the joint. The socket acts as a mold for the fragmented femoral head as it heals.