What Is Perthes Disease?

Perthes disease, also known as Legg-Calvé-Perthes disease, is a childhood hip disorder that primarily affects the ball part of the hip joint. This ball is called the femoral head and sits on top of the femur which is the long bone of the thigh. The femoral head is normally round and fits inside the round socket of the pelvis, called the acetabulum

In Perthes disease, the blood supply to the femoral head is disrupted and all or part of the femoral head dies from the lack of blood flow. This death of the bone cells is called “avascular necrosis” or “osteonecrosis” of the femoral head. The femoral head is less strong after the bone dies and can become flattened due to weight and pressure placed on the bone during normal physical activity. Over a one- to two-year period, the damaged bone in the femoral head is slowly removed and replaced with new bone. For more information on terms relating to Perthes disease, please view our glossary of terms

Brady's Perthes Story


Who Gets Perthes Disease? 

Perthes disease is four to five times more common in boys than girls. Perthes disease most commonly affects children between the ages of 4 to 8. While children between the ages of 2 to 15 may get Perthes, it is less common before age 4 and after age 10. Children who develop Perthes tend to be small for their age, hyperactive, have delayed bone age, and if male, may have some minor genitourinary anomalies like inguinal hernia, hypospadias, and undescended testis. Perthes disease is rarer in African-Americans than in other groups.

What Causes Perthes Disease?

The cause of Perthes disease is currently unknown. Perthes disease is not considered to be inherited since less than 5% of children with Perthes disease have a family history of the disease. There are hip conditions that are inherited that can mimic Perthes disease like multiple epiphyseal dysplasia and other skeletal dysplasias. Read more about theories on the causes of Perthes.

How Common Is Perthes Disease?

Perthes disease is not very common. It is estimated that Perthes disease affects about 5 to 10 per 100,000 children under the age of 15. Because this condition is not common, not many physicians and healthcare providers see this condition and may be unfamiliar with the details of the disease. 

What Are the Symptoms and Signs of Perthes Disease? 

The most common symptoms are limping and groin or leg pain. The child may not complain specifically of hip pain, but instead the child may complain of knee, thigh, or non-specific leg pain which may delay diagnosis. The onset of symptoms can be abrupt during or just after an activity or can come on very gradually. Before seeing a pediatric orthopedic specialist, there may be weeks to months of pain or limping with improvement with rest and worsening with too much activity. 

How is Perthes Disease Diagnosed?

Perthes disease is a disease of exclusion which means that because there are other conditions that can mimic Perthes disease, similar conditions must be ruled out by taking a careful medical history and doing a thorough physical examination. To rule out other conditions, physicians generally ask about family history of hip disorders, family history of early joint replacement, previous hip surgery, past use of steroid medication for asthma or other medical conditions, history of sickle cell disease, history of hip infection, clotting disorders, and endocrine disorders. 

In addition to a medical history and physical examination, x-rays of the hips are required to make the diagnosis of Perthes. In a small number of patients who come to the clinic shortly after the onset of symptoms, the x-rays may be normal if not enough time has passed for x-ray changes to occur. If patient is still suspected of having Perthes disease, a perfusion MRI may helpful to make the diagnosis as it is more sensitive than conventional MRI (Read more).

These images show an example of a perfusion MRI for a child with Perthes disease. A perfusion MRI provides multiple types of images and information of the hips. In the top image, the affected femoral head on the left side of the image appears dark black in the areas of no blood flow (circle). In the bottom image, the brighter white areas around the femoral head (arrows) indicate inflammation of the hip joint. The opposite hip joint appears normal with blood flow to the bone and no inflammation.

What Happens to the Femoral Head in Perthes Disease?

There is a partial or complete disruption of blood flow to the femoral head. With the disruption of blood flow, the bone cells in the affected area of the femoral head die and this is called “osteonecrosis” or “avascular necrosis.” 

There are four stages to Perthes disease. The first stage is called the initial stage or the stage of avascular necrosis. This is the stage when the bone cells die due to the disruption of blood flow and it can last several months. 

Over time, the body sends in cells to remove the dead bone. During this process which can last one to two years, the femoral head is considered to be in the second stage of Perthes disease, called the fragmentation or resorptive stage. Cells called “osteoclasts” are the primary cells involved in this process. As the dead bone is being removed by osteoclasts, it is not immediately replaced by new bone but by fibrous scar tissue which is not as strong as the bone. Unfortunately, when the dead bone is removed, the bone is weakened and is susceptible to flattening or collapse with daily normal activity.

Eventually, as the dead bone is being removed and new bone starts to build up in the femoral head. This is the third stage of Perthes disease which is called the re-ossification stage. The bone building is done by cells called “osteoblasts”. In general, this is the longest stage of Perthes disease and it can last 3 to 5 years. 

When all the bone has been built up in the femoral head, the femoral head is considered to be in the healed stage of Perthes disease which is the fourth and final stage. 

The duration of each stage depends primarily on the age of the child at the start of the disease and the amount of the femoral head that is affected by the loss of blood flow. Younger patients (age 6 and younger) tend to move through the stages faster than older patients.

What Are the X-ray Changes Seen at the Four Stages of Perthes Disease?

  1. Initial stage – The affected femoral head appears a whiter and slightly smaller than the unaffected side. The distance between the femoral head and the inside of the socket may be increased. The top of the femoral head may have a dark fracture line called subchondral fracture or may show mild compression.
  2. Resorptive or fragmentation stage – The femoral head starts to break up into few fragments and shows areas of bone resorption which are seen as darker areas. The femoral head can show mild to moderate extrusion (the head appears slightly out of the socket) if there is increased flattening of the femoral head. Femoral head extrusion also increases the distance between the femoral head and the inside of the socket.
  3. Re-ossification stage – As newly formed bone is built back into the femoral had, white areas reappear on the perimeter of the femoral head and gradually fill in toward the center of the femoral head. 
  4. Healed stage – In this stage, the bone rebuilding is complete and the femoral head has the appearance of normal bone. The shape of the femoral head, however, can be round, oval, or flat depending on how badly the femoral head was flattened during the fragmentation stage and how much growth and reshaping the patient has. This is why the outcome is generally better in younger patients as they have more growth and reshaping potential.

Presented below are x-rays of the first 3 stages of Perthes Disease


What Are Some of the Clinical Problems Associated with Perthes Disease?

The clinical problems associated with Perthes disease can be divided into two main types:

  1. Those problems that occur before reaching the healed stage of Perthes:
  • Pain and limping due to hip joint inflammation 
  • Femoral head extrusion and collapse
  • Some loss of hip joint flexibility due to pain, inflammation, or femoral head flattening
  • A mild shortening of the affected leg of usually ½ inch or less.
  1. Those problems that occur after reaching the healed stage of Perthesa:
  • Possible decrease in hip joint flexibility due to a permanent change in the shape of the femoral head, an enlarged femoral head, and a shortened femoral neck from  growth disturbances.
  • Pain during daily or sports activities due to femoral head impingement (i.e. the deformed, enlarged femoral head is bumping into a part of the socket)
  • Pain and limping due to early arthritis. A deformed femoral head that does not fit well into the socket is more prone to wear-and-tear.

What Are the Outcomes of Perthes Disease?

In Perthes Disease, the term “outcome” generally means how deformed and less round the femoral head is on an x-ray at the healed stage. For example, the more deformed the femoral head is at the healed stage, the greater the risk is for getting hip arthritis as an adult and is considered a poor outcome. Conversely, the more round the femoral head is at healing, the better a child’s outcome will be as an adult. 

The Stulberg radiographic classification (shown above) is an x-ray outcome measure that grades the fermoral head into 5 categories based on the amount of deformity present at the healed stage of the disease. Stulberg classes 1 and 2 include round femoral heads and are both considered good outcomes as the risk for developing hip arthritis as an adult is low. Stulberg 3, 4, 5 represent ovoid, flat, and misfit femoral heads, respectively, and are considered poor outcomes with the risk for developing arthritis in the affected hip as an adult is 50 to 60%. (Read more about Stulberg classification)

It is important to know that the x-ray outcome is different from a functional outcome which looks at patient’s pain and functional level. Many patients with a deformed femoral head function very well and are active and do not have pain as teenagers and adolescents. Some may develop pain later in life as adults. 

What Affects the Outcomes of Perthes Disease?

The x-ray outcome at the healed stage depends on 3 main factors:

  1. Age at onset of the disease. The onset of Perthes before age 6 is better than after age 6. The onset of Perthes after age 9 is generally associated with a poor outcome.
  2. Amount of femoral head involvement. The outcome is poorer if more than 50% of the femoral head is affected by the death of the bone.
  3. Development of certain radiographic changes during the fragmentation stage. A decrease in the height of the lateral part of the femoral head during the fragmentation stage will affect outcome. For example, a poor outcome is expected if the head loses more than 50% of its original height. These radiographic changes are characterized by lateral pillar classifications. Other x-ray changes associated with poor outcome are moderate to severe extrusion of the femoral head and growth disturbance of the growth plate below the femoral head. 

How Is Perthes Disease Treated?

Various treatment methods exist for Perthes disease and the best treatment option depends on several factors such as the age of the child at onset of the disease, the amount of the femoral head involvement, and the stage of the disease at diagnosis. Because of these factors plus the child’s ability to comply with treatment instructions and a doctor’s findings during examination, treatment is individualized. No single treatment method will work for all patients and no single treatment consistently prevents the development of femoral head deformity. 

The primary goals of treatment for Perthes disease are to alleviate pain and to prevent lasting deformity of the femoral head. Because it is easier to prevent or minimize femoral head deformity than to restore the round shape of the femoral head after it has flattened or collapsed, early institution of treatment is important for older patients (age over 8) who do not have a good femoral head reshaping potential. Treatments that restore hip motion and help reshape the femoral head as best as possible are used when the child is diagnosed at a later stage of the disease. Current treatments are not often successful at making the femoral head perfectly round again once it has lost its original shape. 

What Is the Treatment Approach For Patients Who Developed Perthes Disease Before Age 6?

Patients with the onset of Perthes before age 6 generally have a good prognosis and are treated with non-operative means as listed below (Read more about the study on the prognosis of younger patients)

Restriction of long walks, sports, running, and jumping activities

Range of motion exercises with focus on hip abduction and rotation.

Bed rest for few days if hip joint flexibility is severely limited

Weight relief of the affect leg using crutches, walker, or wheelchair if x-ray changes associated with poor outcome are seen

Petrie casts (long leg casts with abduction bar) and abduction bracing if hip is unresponsive to above options or if a patient presents at a later stage of Perthes with hip joint stiffness.

What Is the Treatment Approach For Patients Who Developed Perthes Disease Between Ages 6 to 8?

The treatment options for this age group range from symptomatic, non-operative treatment to operative treatments. It is not clear whether non-operative or operative treatment is better. This uncertainty is due to the fact that one multicenter study showed a better result with femoral osteotomy whereas another multicenter study did not. (Read more about the results of multicenter studies). The International Perthes Study Group is currently conducting another multicenter study to resolve this uncertainty. (Read more about IPSG)

What Is the Treatment Approach For Patients Who Developed Perthes Disease After Age 8 and is Diagnosed in an Early Stage?

There is a general trend toward earlier intervention in older patients (age of onset after age 8) in the initial or early fragmentation stage of Perthes disease. The reason for this approach is to prevent further collapse of the femoral head before it is too late. Two multicenter study results support operative intervention for this age group. At Texas Scottish Rite, a perfusion MRI is used to assess the extent of femoral head involvement before recommending an operation so that we do not operate on patients with a mild disease. The extent of blood flow loss to the femoral head cannot be distinguished using x-rays or conventional MRI at the early stage of Perthes disease. 

Treatment options for this age group include femoral and pelvic osteotomies in which the femoral or pelvic bone are cut and repositioned to place the femoral head in a more protected position within the hip joint socket. There are other procedures, as well, such as the “shelf” procedure, which increases the coverage of the femoral head. 

What Is the Treatment Approach For Patients Who Developed Perthes Disease After Age 8 and is Diagnosed in a Later Stage?

In the mid-fragmentation stage, the hip joint motion may be very restricted and the femoral head deformity may be severe. In these cases, we sometime use 6 weeks of Petrie cast followed by a femoral varus osteotomy or a wide abduction brace called A-frame brace. There is evidence to suggest that a prolonged use of wide abduction brace can improve the shape of the deformed femoral head. 

A placement of an external fixator or hip distraction device to take the pressure off the femoral head is also offered in some centers. The fixator is generally kept in place for 3-4 months and active physiotherapy is required to maintain hip movement.  The beneficial effect of hip distraction using an external fixator is uncertain at this time.

What Is the Treatment Approach For Patients Who Developed Perthes Disease After Age 11?

Occurrence of Perthes disease in this age group is relatively uncommon. The prognosis for this older age group is generally poor. Because of this, the treatment methods used to treat adult femoral head osteonecrosis are being offered to this age group. Those treatment options can include multiple drilling of the femoral head to create bone channels for the blood vessels to grow into the affected femoral head and application of hip distractor. In a limited number of patients, a free vascularized fibular graft is placed into the femoral head. However, at this time, it is uncertain whether these treatments are beneficial or not in this age group.

Current Research on Perthes Disease at TSRHC and the Center for Excellence in Hip Disorders

Several studies are currently active in the Center for Excellence in Hip Disorders, led by Dr. Harry Kim.

  • International Perthes Study Group studies (www.perthesdisease.org)
  • Investigating the role of perfusion MRI on predicting the outcomes of Perthes disease
  • Comparing nonoperative treatment vs surgical treatment for Perthes in patients between age 6-8
  • Comparing short-term vs longer-term non-weight bearing after surgical treatment in patients between age 8-11
  • Long-term follow-up of Operative LCPD
  • Gait/Functional outcomes of adolescent patients with LCPD treated with surgical hip dislocation
  • Clinical and radiographic outcomes of adolescent patients with LCP with surgical hip dislocation

TSRHC Patient Stories

Madelyn's Perthes Story
Madelyn is a very active young girl that did not want her diagnosis of Perthes disease to stop her from participating in sports. Her competitive spirit took her to the swimming pool throughout her treatment where she was able to compete in swim meets and stay active. Please take a moment to listen to Madelyn's story about her experiences with Perthes disease.

Thomas's Perthes Story
Thomas's story about his experience with Perthes disease demonstrates how a diagnosis of Perthes disease can lead to new opportunities and discoveries about one's own potential. Please watch this video about how Thomas and his family managed his treatment and recovery.

View additional Perthes Patient Stories here