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Perthes disease (also known as Legg-Calvé-Perthes disease) is a rare pediatric hip condition. It most often occurs in children 4 to 8 years old. Some studies report cases of Perthes disease in children as young as two and as old as 15. The condition was first described by G. C. Perthes in Germany, A. T. Legg in the United States, and J. Calvé in France. Although the condition has been widely studied for more than 110 years, the exact cause remains unknown.

The condition begins with a disruption of blood flow to the femoral head. The femoral head is the ball-shaped top end of the thigh bone where it joins the hip socket. Each bone in the body requires a supply of blood that delivers oxygen and nutrients to it. Without this blood supply, necrosis (cell death) occurs in the vulnerable area of growing bone at the femoral head. Perthes disease can range from mild (usually in younger children) to severe. In severe cases, the head of the femur flattens due to breakdown of bone and leads to the onset of early osteoarthritis. The long-term outlook is good for most children treated for this disease. However, healing occurs slowly and takes at least 18 to 24 months.

Each year, about one in 10,000 children in the United States develops Perthes disease. It is more common in Caucasian children and affects boys more often than girls. Physical therapists help these children with Perthes disease:

  • Regain motion of the hip joint.
  • Decrease inflammation and pain.
  • Strengthen muscles around the hip.
  • Learn to use prescribed braces or crutches throughout the healing process.

Physical therapists are movement experts. They improve quality of life through hands-on care, patient education, and prescribed movement. You can contact a physical therapist directly for an evaluation. To find a physical therapist in your area, visit Find a PT.

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What Is Perthes Disease?

Perthes disease is a complex bone disorder that can last from several months to years. It occurs only in children and affects boys more than girls (five boys for every one girl). In 10% to15% of cases the disease affects both hips. Children who develop the disease are often physically active and athletic. Some studies show a link between obesity in children and Perthes disease.

During childhood, bone and tissue growth is rapid. In some rare cases as children grow, and for unknown reasons, the blood supply to the ball-shaped head of the femur (thigh bone) can become cut off, causing Perthes disease. This loss of blood supply affects bone growth and can cause the developing bone to lose its round shape where it connects to the hip socket.

Over time and with treatment, blood vessels regrow into the femoral head, which leads to healing and reshaping. But the healing process is slow, and the femoral head is weakened in the process. In some cases, the bone can become permanently deformed and result in hip disorders in adulthood, such as osteoarthritis. Early diagnosis and treatment of Perthes disease are vital to ensure long-term health.

There are four stages in Perthes disease:

Stage 1: Necrosis. Bone cells die during this initial stage. Your child may limp or avoid putting weight on the affected leg, especially if they have been very active. They may complain of hip, thigh, or knee pain and resist moving their hip. These symptoms usually occur without an obvious injury or incident. The initial stage may last several months.

Stage 2: Fragmentation. The body removes dead bone cells and replaces them with new, softer bone. Unfortunately, this softer bone is prone to collapse. When this happens, the head (ball) of the femur can change from a rounded shape to a more flattened shape that no longer fits in the hip socket the way it should. This can limit hip range of motion and affect walking and other activities. This stage usually takes place over 12 to 24 months.

Stage 3: Reossification/healing. Stronger bone begins to develop through a process called reossification. At this stage the head of the femur begins to reform. Ideally it returns to a normal rounded shape that allows for unrestricted movement in the hip socket. This is usually the longest stage of healing and can take up to a few years.

Stage 4: Residual/healed. Once the bone has healed, the shape of the femoral head determines how well the joint moves and how a child functions doing everyday activities and sports. Ideally, the head will be very close to its original round shape, but this depends on many factors. The main factor is the age of the child at start of the disease.

Signs and Symptoms

The first signs of Perthes disease may be limping and hip pain; however, some children also feel pain in the knee. If your child shows any of the following signs or symptoms, see a doctor or physical therapist for an evaluation:

  • Limping that lasts for several days, without a known cause or injury. This is most often one of the first complaints noted by parents. Increased activity (a long hike, running, or sports competition) may make limping worse.
  • Pain on the top of the thigh, in the groin area, or in the knee. This is usually the next symptom reported. Limping may increase and your child may complain of pain when walking.
  • Muscle spasms (twitches) in the thigh, hip, or buttock.
  • Limited range of motion. This is especially common when rotating the foot toward the opposite leg (internal rotation) or moving the thigh away from the body (hip abduction).
  • Weakness and muscle wasting. This can occur at a later stage in the disease process. It can result in trunk sway during walking (the trunk bends over sideways during each step on the affected leg).

In some cases, the bone(s) that support the hip can fracture (break).

How Is It Diagnosed?

A health care provider will take the child's health history. During the exam, they may:

  • Observe the child walking to see if a limp is present.
  • Assess pain in the hip.
  • Determine whether pain is spreading to the knee or thigh.
  • Measure motion at the hip to see if the child has limited movement.
  • Order X-rays (which are required to confirm Perthes disease).

Typically, the child will appear otherwise well, with no general illness, trauma, or a known injury. Orthopedic surgeons and radiologists rely on X-ray images to determine the stage and extent of Perthes disease. Additional tests and imaging, including MRI or bone scans, may be used to rule out other diseases or conditions.

Early diagnosis is crucial to aid full recovery. Several classification groupings exist to describe the extent of Perthes disease and predict recovery. If more than 50% of the femoral head is affected, the potential for regrowth without deformity is lower. Surgery may be needed to help the femoral head keep its shape.

How Can a Physical Therapist Help?

A physical therapist teaches a young child to use arm crutches

Physical therapists are important members of the health care team that works with children who have Perthes disease. A physical therapist will carefully examine the child. They will develop an exercise program designed to help restore normal hip movement and promote age-appropriate functional skills.

Based on each child's condition, a physical therapy treatment plan will be designed to help:

  • Reduce hip pain and inflammation.
  • Restore and maintain hip range of motion and strength.
  • Teach the child how to use crutches, walkers, or other devices to help decrease the stress on the hip when needed.
  • Educate parents and caregivers on safe positioning. This may include how to transfer the child from the car or bed, and other activities to protect the hip through the healing stages.

Your child's physical therapist may work closely with an orthopedist and pediatrician to ensure the best possible treatment outcomes.

If Surgery Is Needed

Sometimes, older children or those with more severe disease may need surgery to keep the femoral head within the hip socket. A physical therapist can develop a treatment program to:

  • Reduce the child's pain and inflammation.
  • Help the child maintain motion in the hip.
  • Educate the child and parents about safe ways to move at home and in the community that follow the surgeon’s guidelines for bearing weight after the operation.
  • Teach exercises for strengthening and improving cardiovascular conditioning.
  • Promote safe activities during all the phases of the healing process.

Can This Injury or Condition Be Prevented?

The exact cause of Perthes disease is not known despite many decades of studying the condition. Current research points to multiple factors that may contribute to the disease, including mechanical, genetic, and systemic conditions. Other factors linked to Perthes disease may include:

  • Exposure to second-hand smoke.
  • Low birth weight.
  • Socioeconomic factors.
  • Obesity.
  • ADHD.

Noticing and identifying symptoms early is crucial to recovery. It allows treatment to begin to reduce or prevent problems in adulthood. Researchers continue to try to understand the cause of Perthes disease and to improve conservative care and surgery.

What Kind of Physical Therapist Do I Need?

All physical therapists are prepared through education and experience to treat patients with Perthes disease. However, you may want to consider:

  • A physical therapist who is experienced in pediatric and orthopedic disorders. These physical therapists may work with you and your child at home, at school, or in the community, in addition to seeing them in a clinic setting.
  • A physical therapist who is a board-certified clinical specialist or who has completed residency, fellowship, or training in pediatric or orthopedic physical therapy. This physical therapist has advanced knowledge, experience, and skills that may apply to rare orthopedic conditions, such as Perthes disease.
  • An experienced pediatric physical therapist who also understands the importance of working with orthopedic surgeons who guide the rehabilitation plan needed to ensure the best possible outcomes for children with Perthes disease.

Physical therapists are movement experts. They improve quality of life through hands-on care, patient education, and prescribed movement. You can contact a physical therapist directly for an evaluation. To find a physical therapist in your area, visit Find a PT.

Find a PT Near You!

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The American Physical Therapy Association believes that consumers should have access to information to help them make informed health care decisions and prepare them for their visit with a health care provider.

The following resources offer some of the best scientific evidence related to physical therapy treatment for Perthes disease. They report recent research and give an overview of the standards of practice both in the United States and internationally. They link to a PubMed* abstract that also may offer free access to the full text, or to other resources. You can read them or print out a copy to bring with you to your health care provider.

Cleveland Clinic. Perthes disease: what is it, causes, symptoms, diagnosis? Updated August 11, 2020. Accessed June 2, 2021.

Pavone V, Chisari E, Vesclo A, Lizzio C, Sessa G, Testa G. Aetiology of Legg-Calve-Perthes disease: a systematic review. World J Orthop. 2019;10(3):145–165. Article Summary in PubMed.

Logan L, Haider S, Brauer C, Mittunen P. Severe bilateral Legg-Calve-Perthes resolved with pamidronate in combination with casts, physiotherapy and adductor tenotomy; a pictorial essay over 11 years. BMJ Case Rep. 2019;12(9):e229919. Article Summary in PubMed.

American Academy of Orthopaedic Surgeons. Perthes disease. Reviewed October 2019. Accessed June 2, 2021.

Kessler J, Cannamela P. What are the demographics and epidemiology of Legg-Calve´-Perthes disease in a large southern California integrated health system? Clin Orthop Relat Res. 2018;476(12):2344–2350. Article Summary in PubMed.

US Library of Medicine, Medline Plus. Legg-Calve-Perthes disease. Accessed July 30, 2021.

Rampal V, Clement J, Solla F. Legg-Calve-Perthes disease: classifications and prognostic factors. Clin Cases Miner Bone Metab. 2017;14(1):74–82. Article Summary in PubMed.

National Organization for Rare Disorders. Legg Calvé Perthes disease: symptoms of Legg Calvé Perthes disease. Updated 2016. Accessed June 2, 2021.

Mazloumi S, Ebrahimzadeh M, Kachooei A. Evolution in diagnosis and treatment of Legg-Calve´-Perthes disease. Arch Bone Jt Surg. 2014;2(2):86–92. Article Summary in PubMed.

Pediatric Orthopaedic Society of North America. Perthes disease. Accessed June 2, 2021.

*PubMed is a free online resource developed by the National Center for Biotechnology Information. PubMed contains millions of citations to biomedical literature, including citations in the National Library of Medicine’s MEDLINE database.

The Academy of Pediatric Physical Therapy contributed to this consumer resource. It is for informational purposes only and is not intended to represent the position of APTA Pediatrics.