Can you please explain what a hinge abduction is? Our 11-year old had Legg-Perthes disease when he was five years old. He has since developed increasing pain over the years because of this hinge abduction.

Perthes disease (sometimes referred to as Legg-Calvé-Perthes) is the collapse of the hip joint due to a loss of blood supply. It occurs most often in children between the ages of four and eight.

In this condition, the blood supply to the capital femoral epiphysis (growth center of the hip) is disturbed, causing the bone in this area to die. The blood supply eventually returns, and the bone heals. How the bone heals determines how much problem the condition will cause. This condition can lead to serious problems in the hip joint later in life.

Hinge abduction is abnormal movement of the hip that can occur when a femoral head, deformed by Perthes disease does not slide as it should within the acetabulum (hip socket).

In such cases, a large portion of the femoral head is not under the acetabulum. As a result, during hip movement, a portion of the bone and cartilage from the deformed femoral head gets pinched against the acetabular rim. It is a painful condition that can be corrected.

Sometimes traction to pull the head down into a better position works. Surgery is another option. There are a variety of surgical procedures available. Which one is used depends on the severity of the condition.