Legg-Calve-Perthes (LEG-kahl-VAY-PER-tuz) disease is a childhood condition that occurs when blood supply to the ball part (femoral head) of the hip joint is temporarily interrupted and the bone begins to die.
This weakened bone gradually breaks apart and can lose its round shape. The body eventually restores blood supply to the ball, and the ball heals. But if the ball is no longer round after it heals, it can cause pain and stiffness. The complete process of bone death, fracture and renewal can take several years.
To keep the ball part of the joint as round as possible, doctors may use a variety of treatments that keep it snug in the socket portion of the joint. The socket acts as a mold for the fragmented femoral head as it heals.
Signs and symptoms of Legg-Calve-Perthes disease include:
- Pain or stiffness in the hip, groin, thigh or knee
- Limited range of motion of the hip joint
Legg-Calve-Perthes disease usually involves just one hip. Both hips are affected in some children, usually at different times.
When to see a doctor
Make an appointment with your doctor if your child begins limping or complains of hip, groin or knee pain. If your child has a fever or can't bear weight on the leg, seek emergency medical care.
Legg-Calve-Perthes disease occurs when too little blood is supplied to the ball portion of the hip joint (femoral head). Without an adequate blood supply, this bone becomes unstable, and it may break easily and heal poorly. The underlying cause of the temporary reduction in blood flow to the femoral head is still unknown.
Risk factors for Legg-Calve-Perthes disease include:
- Age. Although Legg-Calve-Perthes disease can affect children of nearly any age, it most commonly begins between ages 4 and 8.
- Your child's sex. Legg-Calve-Perthes is up to five times more common in boys than in girls.
- Race. White children are more likely to develop the disorder than are black children.
- Genetic mutations. In a small number of cases, Legg-Calve-Perthes disease appears to be linked to mutations in certain genes.
Children who have had Legg-Calve-Perthes disease are at higher risk of developing hip arthritis in adulthood — particularly if the hip joint heals in an abnormal shape. If the hip bones don't fit together well after healing, the joint can wear out early.
In general, children who are diagnosed with Legg-Calve-Perthes after age 6 are more likely to develop hip problems later in life. The younger the child is at the time of diagnosis, the better the chances for the hip joint to heal in a normal, round shape.
During the physical exam, your doctor may move your child's legs into various positions to check range of motion and see if any of the positions cause pain.
These types of tests are vital to the diagnosis of Legg-Calve-Perthes disease and may include:
- X-rays. Initial X-rays may look normal because it can take one to two months after symptoms begin for the changes associated with Legg-Calve-Perthes disease to become evident on X-rays. Your doctor will likely recommend several X-rays over time, to track the progression of the disease.
- Magnetic resonance imaging (MRI). This technology uses radio waves and a strong magnetic field to produce very detailed images of bone and soft tissue inside the body. MRIs often can visualize bone damage caused by Legg-Calve-Perthes disease more clearly than X-rays can, but are not always necessary.
- Bone scan. In this test, a small amount of radioactive material is injected into a vein. The material is attracted to areas where bone is breaking down and rebuilding, so these areas show up on the resulting scan images. This test can reveal evidence of Legg-Calve-Perthes disease earlier than X-rays can, but MRIs have largely replaced bone scans for this diagnosis.
In Legg-Calve-Perthes disease, the complete process of bone death, fracture and renewal can take several years. The types of treatment recommended will depend on the:
- Age when symptoms began
- Stage of the disease
- Amount of hip damage
As Legg-Calve-Perthes disease progresses, the ball part of the joint (femoral head) weakens and fragments. During healing, the socket part of the joint can serve as a mold to help the fragmented femoral head retain its round shape.
For this molding to work, the femoral head must sit very snugly within the socket. Sometimes this can be accomplished with a special type of leg cast that keeps the legs spread widely apart for four to six weeks.
Some children require surgery to help keep the ball of the joint snug within the socket. This procedure may involve making wedge-shaped cuts in the thighbone or pelvis to realign the joint.
Surgery usually isn't needed for children younger than 6. In this age group, the hip socket is naturally more moldable, so the ball and socket typically continue to fit together well without surgery.
Some children, particularly very young ones, may need only conservative treatments or even no treatment at all. Conservative treatments may include:
- Activity restrictions. Running and jumping might accelerate hip damage.
- Crutches. In some cases, your child may need to avoid bearing weight on the affected hip. Using crutches can help protect the joint.
- Physical therapy. As the hip stiffens, the muscles and ligaments around it may shorten. Stretching exercises can help keep the hip more flexible.
You'll probably first bring your concerns to the attention of your child's doctor. After an initial evaluation, your child may be referred to a doctor who specializes in bone problems in children (pediatric orthopedist).
What you can do
Before your appointment, you may want to write a list of answers to the following questions:
- When did these symptoms begin?
- Does any particular leg position or activity make the pain worse?
- Did any of your relatives have similar symptoms when they were children?
- Does your child have any other medical problems?
- What medications or supplements does your child take regularly?
What to expect from your doctor
Your doctor may ask some of the following questions:
- What are your child's symptoms?
- Have they gotten worse over time?
- Do the symptoms seem to come and go?
- Is your child active?
- Has your child experienced an accident or injury that might have caused hip damage?
- If your child's symptoms include pain, where is the pain located?
- Does activity make your child's symptoms worse?
- Does resting ease your child's discomfort?