Perthes Disease (Legg-Calvé-Perthes)

Description

Perthes disease is a childhood hip condition in which the blood supply to the “ball” of the hip (the femoral head) is temporarily lost. Without its blood supply, part of the bone weakens and can flatten or collapse; over the following years the body restores the blood supply and rebuilds the bone. It most often affects children around ages 4 to 10 (more commonly boys), and usually just one hip.

How it happens (mechanism)

For reasons that are still not well understood (the medical word is idiopathic), the blood supply to the growing femoral head is interrupted, and that bone loses its living blood supply — a process called avascular necrosis. The softened head can lose its round shape under the loads of standing and walking. Then, over months to a few years, blood vessels grow back, dead bone is gradually replaced, and the head re-forms. The condition moves through stages — loss of blood supply, fragmentation, rebuilding, and final remodeling — and the vulnerable window is the soft phase, when the head can deform.

What matters

The long-term outcome depends largely on the shape the femoral head ends up with. A round head that fits the socket does well; a flattened, mushroom-shaped head leads to stiffness, catching, and arthritis. This is why the guiding principle of treatment is containment — keeping the soft, healing head well-seated and centered in the round socket so that the socket acts as a mold and the head re-forms round. Keeping the hip moving is equally important. Age matters too: younger children have more growth and remodeling ahead of them and tend to do better, while older children with more of the head involved are at higher risk and more likely to need surgery.

Symptoms

Common signs include:

• A limp, which may come and go and is often not very painful
• Pain in the hip, thigh, or knee
• Stiffness and reduced hip motion, especially spreading the leg out and turning it inward
• Gradual onset over weeks, sometimes with periods of improvement and flare

How it is diagnosed

X-rays of the pelvis, including a frog-leg lateral view, show the stages of the disease and are repeated over time to track it. An MRI can detect the loss of blood supply early, before changes are visible on X-ray.

Treatment

Treatment depends on the child’s age and how much of the head is involved. Younger children with limited involvement are often managed without surgery — activity modification, anti-inflammatory medicine, and physical therapy to preserve motion, sometimes with bracing or casting to help contain the head. Older children, or those with more of the head affected, may benefit from surgery (an osteotomy of the femur or pelvis) to better contain the head in the socket. The disease runs its course over roughly 2 to 4 years, and children are followed until they are finished growing.

Recovery and long-term outlook

Many children, especially younger ones, heal with a good, round hip and do well. The outcome is closely tied to the final shape of the femoral head and the age at onset; some children develop hip stiffness or arthritis as adults. Because the process is long and cyclical, steady follow-up matters.

When to call the doctor

Have your child evaluated for a limp or for hip, thigh, or knee pain that lasts more than a week or two, or for hip stiffness — and remember that knee or thigh pain in a child can actually be coming from the hip.

Learn more

OrthoInfo (AAOS) — Perthes Disease: orthoinfo.aaos.org

This information is for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. For specific concerns about your child, consult a board-certified, fellowship-trained pediatric orthopaedic surgeon.