Perthes Disease

What is Perthes disease?

Perthes disease is a childhood hip condition in which the blood supply to the rounded top of the thigh bone, called the femoral head, is temporarily interrupted. Without enough blood, part of the bone weakens and may collapse or change shape. Over time the blood supply returns and the bone slowly heals and rebuilds itself. This process can take several years. The condition is also known as Legg-Calve-Perthes disease, named after the three doctors who described it, and is sometimes shortened to LCPD.

Perthes disease in children most often appears between the ages of about 4 and 10, although it can occur in younger and older children. It is more common in boys than in girls, and in most children only one hip is affected. When both hips are involved, they are usually affected at different times rather than at once.

The medical term for this type of bone damage is avascular necrosis, which means bone tissue dies because it loses its blood supply. In Perthes disease this happens in a growing child, so the body has a strong ability to repair the bone. The main concern is not whether the bone heals, but the shape it heals into. A femoral head that remains round and fits well in the hip socket usually works well for life. A head that heals flat or misshapen may lead to stiffness, limping, and early wear and tear of the joint in adulthood.

Perthes disease symptoms

Perthes disease symptoms often begin gradually and can be easy to miss at first. Many parents notice a limp before the child complains of pain. Common signs include:

• A limp, often painless or only mildly painful in the early stages
• Pain in the hip, groin, thigh, or knee, which may come and go
• Pain that worsens with activity and improves with rest
• Reduced range of motion in the hip, especially turning the leg inward or moving it out to the side
• Stiffness in the hip after periods of rest
• Muscle wasting in the thigh or buttock on the affected side over time
• One leg appearing slightly shorter than the other in later stages

Pain felt in the knee is common in childhood hip problems because the hip and knee share nerve pathways. A child who repeatedly complains of knee pain, but whose knee examination is normal, may in fact have a hip problem. This is one reason doctors usually examine the hip when a child has an unexplained limp.

Symptoms tend to change with the stage of the disease. In the early stage, when the blood supply is interrupted, a child may have mild pain and a limp that comes and goes. During the fragmentation stage, when the weakened bone breaks down and is absorbed, pain and stiffness are often at their worst. As new bone forms during the reossification stage, symptoms usually ease. In the final healed stage, symptoms depend largely on how round the femoral head has become. Some children have very few symptoms throughout, while others have significant pain for months.

Causes and risk factors

The exact cause of Perthes disease is not fully understood. What is known is that blood flow to the femoral head is disrupted, leading to bone death and later repair. Why the blood flow stops in the first place remains unclear, and it is likely that several factors combine in an individual child. Ideas that researchers have explored include problems with blood clotting, differences in the small blood vessels supplying the hip, and repeated minor stress on the growing hip, but none of these has been proven to be the single cause.

Several factors appear to be associated with a higher chance of developing the condition:

• Age: most cases occur in children between roughly 4 and 10 years old
• Sex: boys are affected more often than girls
• Small body size: affected children are often shorter than average for their age, and bone maturity may lag behind their actual age
• High activity levels: very active children may be somewhat more likely to be affected
• Exposure to tobacco smoke: secondhand smoke has been linked to a higher risk in some studies
• Family history: Perthes disease occasionally runs in families, although most cases occur without any relative having had it
• Certain blood conditions: some clotting disorders have been studied as possible contributors

It is important to understand that Perthes disease is not caused by anything a child or parent did or failed to do. It is not an infection, it is not contagious, and it does not result from a single injury, although a child may first notice pain after a fall or a period of vigorous play.

Diagnosis

Diagnosis usually begins with a careful history and physical examination. The doctor will ask when the limp or pain started, whether it changes with activity, and whether there was any injury or illness. During the examination the doctor will watch the child walk and gently move the hip to check its range of motion. Limited ability to rotate the hip inward or to move the leg outward is a common finding. The doctor may also measure both legs to look for a difference in length and check the thigh muscles for wasting.

Imaging is needed to confirm the diagnosis and to judge how much of the femoral head is involved. Tests your child’s doctor may use include:

• X-rays: the main tool for diagnosis. X-rays of both hips, taken from the front and with the legs in a frog-like position, show changes in the shape and density of the femoral head. Very early in the disease, X-rays can look normal, so repeat X-rays after a few weeks may be needed.
• Magnetic resonance imaging (MRI): a scan that uses magnets and radio waves to create detailed pictures of bone and soft tissue. MRI can detect the loss of blood supply before X-ray changes appear and can show how much of the femoral head is affected.
• Bone scan: a test in which a small amount of a safe radioactive tracer is injected and its uptake in the bone is measured. Reduced uptake in the femoral head suggests loss of blood supply. This test is used less often now that MRI is widely available.
• Blood tests: these do not diagnose Perthes disease, but may be ordered to rule out infection or inflammatory conditions that can cause similar symptoms.

Doctors also use classification systems to describe how severe the disease is, based on how much of the femoral head has collapsed on X-ray. These systems help guide treatment decisions and give a general idea of the likely outcome. The child’s age at diagnosis is also considered, because younger children have more growing time left for the bone to remodel into a good shape.

Other conditions that can cause a limp and hip pain in children include transient synovitis, which is a short-lived inflammation of the hip lining, hip joint infection, and slipped capital femoral epiphysis, in which the growth plate at the top of the thigh bone shifts. Part of the diagnostic process is ruling these out, as some of them need very different and sometimes urgent treatment.

Perthes disease treatment

The goal of Perthes disease treatment is to keep the femoral head round and well seated in the hip socket while the bone heals, and to preserve hip movement. Because the disease runs its own course over time, treatment focuses on protecting the hip rather than curing the underlying blood supply problem. The approach depends on the child’s age, the amount of femoral head involved, the stage of disease, and how well the hip is moving. In many cases a pediatric orthopedic specialist, a doctor who treats bone and joint problems in children, oversees care.

Observation and activity modification

For younger children with mild involvement, doctors may recommend regular monitoring with examinations and X-rays, together with changes to daily activity. Running, jumping, and high-impact sports are often limited to reduce stress on the softened bone. Swimming and cycling are frequently allowed because they keep the hip moving without heavy loading. This period of restriction can last many months, which is often the hardest part of treatment for active children.

Medication

There is no medicine that restores blood flow or speeds up healing in Perthes disease. Over-the-counter anti-inflammatory medicines may be used to ease pain and reduce inflammation in the joint, always under the guidance of the child’s doctor. Some medications are being studied for their potential to protect bone during the fragmentation stage, but these are not standard treatment.

Physical therapy and maintaining motion

Keeping the hip flexible is a central part of care. A physical therapist may teach stretching exercises to maintain range of motion, particularly the ability to move the leg outward. Parents are often shown how to help with these exercises at home. Good motion helps the femoral head stay positioned within the socket, which supports healing in a round shape.

Rest, crutches, and casting

During painful flare-ups, a period of rest, sometimes with crutches or a wheelchair to take weight off the hip, may be advised. If the hip becomes very stiff, doctors may recommend a short hospital stay with traction, which gently pulls on the leg to relieve muscle spasm. In some cases a cast or brace is applied to hold the legs apart in a position that keeps the femoral head deep in the socket. Casts and braces are used less frequently than in the past, but they still have a role for selected children.

Surgery

Surgery may be recommended for older children, for those with more extensive involvement of the femoral head, or when the femoral head has begun to move partly out of the socket. The most common procedures are types of osteotomy, in which a bone is cut and repositioned. A femoral osteotomy reshapes the upper thigh bone so the femoral head points more directly into the socket. A pelvic osteotomy reshapes the socket so it covers more of the femoral head. After surgery a cast is often worn for several weeks, followed by rehabilitation to rebuild strength and movement. For older children and adolescents whose hips have already healed in a misshapen form, other procedures may be considered to improve fit and reduce pain.

Rehabilitation

Whether or not surgery is performed, rehabilitation continues throughout the healing years. This typically includes ongoing exercises, gradual return to activity as X-rays show new bone forming, and regular follow-up. Within a hospital group such as Acibadem, this type of care is typically coordinated through the Orthopedics & Joint Center, working with pediatric specialists and physical therapists.

Living with Perthes disease and outlook

Perthes disease is a long-term condition in childhood, usually lasting two to five years from first symptoms to full healing of the bone. During this time families adjust to activity limits, repeated appointments, and periods of pain. Explaining the condition to teachers and coaches can help a child stay involved in school and social life while avoiding activities that could stress the hip.

The long-term outlook varies. Children who are younger at diagnosis and who have less of the femoral head involved generally do better, because they have more years of growth in which the bone can remodel into a rounder shape. Older children and those with more severe collapse are more likely to be left with some flattening of the femoral head. Many people who had Perthes disease as children have hips that function well into adulthood. Others develop stiffness, a persistent limp, a slight difference in leg length, or hip arthritis earlier than expected, sometimes requiring hip replacement in middle age. It is not possible to predict any individual child’s outcome with certainty.

Emotional support matters. Children may feel frustrated at being unable to keep up with friends, and some experience low mood during long periods of restriction. Talking openly, finding permitted activities the child enjoys, and involving the care team when worries arise can all help. Regular follow-up into the teenage years is often recommended so any late problems can be identified early.

Frequently asked questions

What are the first signs of Perthes disease in children?

The first sign is often a limp that parents notice before the child mentions any pain. When pain is present it is usually mild, may be felt in the groin, thigh, or knee rather than the hip itself, and tends to be worse after activity. Because these signs can be subtle and come and go, a persistent limp in a child should be assessed by a doctor.

Is Legg-Calve-Perthes disease the same as Perthes disease?

Yes. Legg-Calve-Perthes disease, Perthes disease, and the abbreviation LCPD all refer to the same condition, in which the blood supply to the femoral head is temporarily lost in a growing child. The longer name recognizes the three physicians who described it independently in the early twentieth century.

Does Perthes disease go away on its own?

The bone in Perthes disease does heal on its own over time as blood supply returns, usually over a period of years. However, healing without care may leave the femoral head flattened, which can cause long-term problems. Treatment aims to guide this natural healing so the hip keeps a good shape, which is why medical follow-up is recommended even in mild cases.

Can a child with Perthes disease play sports?

This depends on the stage of the disease and the doctor’s advice. High-impact activities such as running, jumping, and contact sports are usually limited while the bone is soft, because repeated pounding can worsen collapse. Low-impact activities such as swimming are often encouraged. As X-rays show new bone forming, activities are usually reintroduced gradually.

Will my child need surgery for Perthes disease?

Not necessarily. Many children, particularly younger ones with limited involvement, are treated without surgery using activity changes, physical therapy, and monitoring. Surgery is more likely to be recommended for older children, for more extensive disease, or when the femoral head is not staying well positioned in the socket. Your child’s orthopedic specialist may discuss the options based on the specific findings.

What is the long-term outlook after Perthes disease?

Outcomes range widely. Many people have good hip function throughout life, especially if the femoral head heals in a round shape. Others have some lasting stiffness, a leg length difference, or develop arthritis in the affected hip earlier than usual. Younger age at onset and less involvement of the femoral head are generally associated with better results, but no outcome can be guaranteed.

Can Perthes disease affect both hips?

In most children only one hip is affected. When both hips are involved, it usually happens at different times rather than simultaneously. If both hips appear affected at the same time and at the same stage, doctors may look for other conditions that can mimic Perthes disease.

When to see a doctor

Any child with a limp that lasts more than a few days, or hip, thigh, or knee pain without an obvious cause, should be examined by a doctor. Early assessment allows other conditions to be ruled out and, if Perthes disease is present, gives the best chance of protecting the hip during healing.

Seek urgent medical attention if a child has any of the following:

• Sudden inability to bear weight on the leg or to walk
• Severe hip or groin pain that comes on quickly
• Fever together with hip pain or a limp, which could indicate a joint infection
• A hip that appears swollen, red, or hot to the touch
• Pain following a fall or injury that does not settle
• The child appearing generally unwell, unusually drowsy, or refusing to move the leg

For children already diagnosed with Perthes disease, contact the care team if pain suddenly worsens, the hip becomes noticeably stiffer, the limp changes, or the child develops new symptoms in the other hip. These changes may mean the treatment plan needs to be reviewed.