Hip Dysplasia & Perthes

What Is Legg-Perthes?

Legg-Perthes, also known as Legg-Calvé-Perthes, is a condition in which a child’s hip joint is abnormal, and the blood supply to the head of the thighbone is temporarily stopped. Over a one- to two-year period, the bone slowly collapses and replaces itself with new bone. The condition can cause pain and stiff joints for a period of time. Early diagnosis of Legg-Perthes can improve the long-term outcome.

Stages of Legg-Perthes

1. Avascular phase – The blood supply to the thighbone stops. Patients are rarely seen this early, and their X-rays may appear to look normal.
2. Revascular phase – The blood supply to the thighbone is restored. Children are most often seen during this phase because it’s when they usually begin to have symptoms. The X-rays show noticeable differences during this stage.
3. Collapse phase – Dead bone cells collect, and the ball of the thighbone appears to fragment and collapse.
4. Healing phase – The flattened top of the thighbone is replaced with new bone. The goal of treatment is to keep the soft thighbone in the socket until new bone forms.
5. Healed phase – There is no further bone formation in the thighbone, but the shape may continue to round until the end of growth at skeletal maturity.

What Causes Legg-Perthes?
The cause of Legg-Perthes is unknown. It is more common in boys, especially those who are very active, and it is usually found between the ages of 3 and 12. Legg-Perthes is not the result of a fall, jump or injury. Doctors have studied the following as possible causes:

• Genetics
• Environment
• Trauma
• Hematologic (blood) abnormalities
• Synovitis (inflammation of the joint space)

How Is Legg-Perthes Treated?
Depending on the child’s symptoms, age and the severity of the condition, one or more of the following treatments may be prescribed:

• Pain control
• Activity restrictions
• Leg exercises - designed to keep the hips moving
• Crutches - to protect and rest the hip while the child is walking
• Cast - to keep the thigh bone in the correct position
• Traction - to relieve pain and allow the hip to regain motion
• Surgery - to place the thigh bone into the hip socket, allow the bone to heal round and smooth and improve circulation
• Adductor tendon release is a surgical release of the groin tendon(s) to allow the hips to be spread farther apart. A cast is put on both legs with a removable bar placed between the legs to hold them in a spread position. This helps place the ball of the thighbone into the hip socket.
• Osteotomy is a surgical procedure to cut the bone(s) of the hip and/or thigh in order to position the ball of the thighbone more deeply into the hip socket. A hip spica cast, which covers the legs up to the chest, is sometimes required.

Goals of treatment are to maintain the child’s hip motion, decrease pain and reduce the likelihood of arthritis and/or development of a limb length discrepancy.