Legg-Calve-Perthes Disease

What is Legg-Calve-Perthes disease?

Legg-Calve-Perthes disease is a rare condition that affects the hips of children aged 2 to 12. It starts when the head of the femur bone (the “ball” in the “socket” of the hip joint) temporarily loses its blood supply. When blood stops flowing to the bone, the tissue starts to die. After a while, the blood flow returns, and the bone slowly repairs itself. But it may not have its original shape and size.

Legg-Calve-Perthes disease belongs to a group of disorders called osteochondroses, which involve the degeneration and regeneration of the growing end of a bone. It occurs unexpectedly and for unknown reasons. It progresses in stages, and the whole process can take several years. How much it affects your child depends on how much their bone changes. With treatment, the long-term prognosis (outlook) is good.

Legg-Calve-Perthes disease (LCPD) goes by various other names, including:

• Perthes disease.
• Perthes syndrome.
• Legg Calve.
• Legg-Perthes.
• Calve-Perthes.
• Coxa plana.

How rare is Perthes disease?

Estimates suggest Legg-Calve-Perthes disease affects around 1 in 12,000 children worldwide. It’s five times more common in kids assigned male at birth (AMAB) than kids assigned female at birth (AFAB).

What age is Legg-Calve-Perthes most common?

Perthes disease is most common in kids ages 5-7. But it can affect kids as young as 2 or as old as 12.

Is Legg-Calve-Perthes disease permanent?

Perthes syndrome triggers a process of degeneration and regeneration in your child’s femur bone, which can last several years. The condition is temporary, but it can cause permanent changes.

Can Perthes disease cause problems later in life?

If the shape of your child’s femur head changes a lot, it might not fit properly in their hip socket anymore. Treatment can help, but if it continues not to fit, they can develop hip problems later in life.

What are the signs and symptoms of Legg-Calve-Perthes disease?

Signs and symptoms of Perthes develop over time and often with no clear beginning. You or your child might start to wonder what’s up when symptoms appear and don’t seem to ever get better.

Early symptoms might include:

• A limp. Your child may favor one leg while walking to keep weight off the affected side. A limp often appears before your child notices any pain. They may not know why they’re limping.
• Hip pain. If your kid has pain, it’s most likely to occur early in the disease process, when the bone has lost its blood supply and it’s starting to degenerate. Pain worsens with activity.
• Referred pain. Some kids may feel pain in their knees, thighs, pelvises or abdomens instead.
• Leg cramps. Kids may experience muscle spasms in the leg muscles connected to their hip joints.

Later signs and symptoms of LCPD may include:

• Trendelenburg gait. This is an abnormal walking pattern that’s characteristic of hip problems. Weak hip muscles cause the pelvis to tilt downward on the affected side as your child walks.
• Limited range of motion. Your child may have difficulty rotating their hip. They may not be able to open their thighs outward or turn their knees inward as far as they used to.
• Muscle atrophy. You may notice loss of muscle mass in your child’s thighs and buttocks.
• Leg length discrepancy. One leg may appear shorter than the other.

What causes Legg-Calve-Perthes disease?

Perthes disease develops when blood supply to the head of the femur bone temporarily slows or stops. This is called ischemia. Since the bone depends on blood supply for oxygen and nutrients, it starts to die and break down without them. This process is called avascular necrosis (osteonecrosis).

Normally, ischemia might happen if a blood vessel gets blocked or compressed. Artery disease or a blood clot might block it from the inside, or swelling might compress it from the outside. But researchers don’t know what causes ischemia in LCPD. It’s possible that different things cause it in different kids.

Risk factors

Research suggests that about half of kids who develop LCPD have some type of blood clotting disorder. Another suggested cause is a traumatic injury or repetitive strain injury that caused enough swelling to cut off blood flow to the bone. Around 10% of cases seem to relate to an inherited gene mutation.

Factors that may increase your child’s risk of developing Legg-Calve-Perthes include:

• Delayed skeletal growth.
• Low birth weight.
• Short stature.
• Abnormal teeth.
• Low socioeconomic status.
• Secondhand smoke exposure.
• Blood clotting disorders.
• HIV infection.
• Involvement in sports or gymnastics.
• Inherited mutations in the COL2A1 gene.

How will Perthes disease affect my child?

While Legg-Calve-Perthes is active, the head of your child’s femur bone in their hip socket will go through a process of degeneration (breakdown) and then regeneration (rebuilding). The breakdown phase may take up to a year, and the rebuilding and remodeling phase may last two to five years.

Some kids have more tissue loss than others. This might be because they have more severe ischemia, or it lasts longer, or they use their bone too much while it’s weakened, causing additional damage. In some kids, the rounded heads of their femurs collapse and flatten. This makes them fit poorly in their hip sockets.

When the bone begins to rebuild, it has another chance to restore its proper shape and fit. But different kids have different amounts of regrowth. Some femurs never recover their former size and shape. Others may overgrow the hip socket. Your healthcare provider will try to influence these outcomes.

Some kids might need to immobilize their hips in a cast for some time. Others might need surgery. These treatments can help the bone regrow correctly. Kids who continue to have poorly fitted hip joints will have ongoing symptoms. Hip dysplasia (a poor fit) can lead to complications like arthritis later in life.

How is Legg-Calve-Perthes disease diagnosed?

A healthcare provider will begin with a thorough physical examination, then follow up with X-rays to look at your child’s bones. X-rays can show evidence of Perthes syndrome, as well as the stage and severity of the disease. In some cases, they might order an MRI (magnetic resonance imaging) to see certain features in more detail.

What is the treatment for Legg-Calve-Perthes disease?

Treatment for Legg-Calve-Perthes depends on how severe the disease is, what stage it’s in and how old your child is. In general, younger kids, whose bones grow faster, tend to do better with less intervention, while older ones might need more. A healthcare team will develop a personalized treatment plan.

This plan may include:

• Restricted activity and weight bearing on their affected hip. Your child might need to stop or limit walking for a while, or use an assistive walking device, like crutches, to get around.
• Nonsteroidal anti-inflammatory drugs (NSAIDs). These over-the-counter (OTC) medications can help manage pain and reduce inflammation in the hip joint. They include aspirin and ibuprofen.
• Physical therapy. A physical therapist will work with your child to rehabilitate their hip by prescribing special exercises. You might need to help your child practice their exercises.
• Traction. An orthopedic traction device applies gentle, progressive force to gradually stretch or pull the hip joint into alignment. This treatment takes place over a series of several days.
• Casts or braces. During the remodeling phase, your provider might suggest using a cast or brace to keep the bone fixed in the socket. The socket can help mold the bone as it regrows.
• Surgery. Some children might need surgery to help reshape and refit the bone in the socket. This is called osteotomy. Some might need arthroplasty to extend or reshape the hip socket.

Can Perthes disease be prevented?

Unfortunately, no. There are no known ways to prevent Perthes disease.

What is the outlook for Legg-Calve-Perthes disease?

If your child has developed Legg-Calve Perthes, you can expect a healthcare journey of several years, with different phases in it. This will intrude on their childhood, to some extent — less for some than others. But when it’s over, most can return to their activities without limitations or ongoing symptoms.

If your child is younger than 7, they’re more likely to recover fully with conservative treatments. If they’re older than 7, they’re more likely to need surgery. Kids who don’t get the right treatment at the right time, and whose femur bones remain deformed, can develop hip osteoarthritis later in life.

What questions should I ask my healthcare provider about Perthes disease?

If your child has Legg-Calve-Perthes, you’ll probably have many questions about their treatment and expected prognosis. Your provider will do their best to forecast what to expect for your child.

You might want to ask:

• What stage is the disease in?
• How severe is it?
• How should we adjust my child’s lifestyle or activities?
• What factors may have contributed to their condition?
• What symptoms or changes should we look out for during treatment?
• What should I tell my child about what to expect?