Our eight-year-old boy has Perthes disease. The plan is to do surgery to rebuild the hip socket. How is this going to help?

Perthes disease is a condition that affects the hip in children between the ages of four and eight. It’s also known as Legg-Calvé-Perthes disease in honor of the three physicians who each separately described the disease back in 1910.

In this condition, the blood supply to the growth center of the hip (the capital femoral epiphysis) is disturbed, causing the bone in this area to die. Over time, the blood supply comes back and the bone heals. This condition can lead to serious problems in the hip joint later in life. How the bone heals determines the final result.

Studies show a key factor in Perthes disease is the shape of the acetabulum (hip socket). The acetabulum is a cup-shaped, curved part of the pelvis that forms the socket. It forms a cover or shelf over the femoral head to hold the hip in the socket.

In Perthes disease, the femoral head disintegrates from lack of blood. As this happens, the acetabulum starts to change shape too. The lateral or outside margin flattens out and can even slope upwards. Without a deep socket, the femur can slip out or dislocate.

To rebuild the acetabular shelf, the surgeon will take a pie-shaped piece of bone from the patient’s pelvis and wedge it in above the acetabulum. The extra bone hangs over the femoral head and extends the coverage. With less likelihood of dislocation, the hip motion is saved, and there’s a better chance the acetabulum and the femoral head will keep their original shape.