Understanding Perthes Disease: A Childhood Hip Disorder – Children's Orthopaedic and Scoliosis Surgery Associates, LLP
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Understanding Perthes Disease: A Childhood Hip Disorder

September 5, 2025:

Legg-Calvé-Perthes disease, commonly known as Perthes disease, is a serious childhood hip condition that affects the femoral head (the ball on top of the thigh bone) The disease occurs when the blood supply to this area is temporarily disrupted, leading to the death of bone cells. This process, called avascular necrosis, weakens the bone, which can then fracture and collapse. 

Legg-Calve-Perthes Disease

1. What Causes Perthes Disease?

The exact cause of Perthes disease is still not fully understood. Research suggests a combination of factors that may contribute to its development. Possible causes include:

  • Blood vessel abnormalities, such as blockages or clots
  • Repetitive stress or trauma to the hip joint
  • Genetic predispositions. Studies have explored a link between certain genetic mutations, specifically in the COL2A1 gene, and the disease. This gene is vital for producing a type of collagen found in cartilage.

2. Who is at Risk?

Perthes disease often affects children between the ages of 4 and 10. Boys are more likely to develop the condition than girls, with a male-to-female ratio of about 4:1. Other risk factors include: 

  • Delayed skeletal growth
  • Low birth weight
  • Short stature for age
  • Certain blood-clotting disorders

    • 3. The Four Stages of Perthes Disease

    The disease progresses through four distinct stages that can span several years. Understanding these stages is key to effective management and treatment.

    1. Initial Phase (Onset): The blood supply to the femoral head is interrupted and the bone tissue begins to die. This is the period of avascular necrosis.
    2. Fragmentation Phase: The weakened bone breaks down and is reabsorbed by the body. This stage can last up to a year and is often when symptoms become most noticeable.
    3. Reossification Phase: The body starts to produce new bone to replace the fragmented dead bone. This is a critical period where the shape of the femoral head can be influenced by treatment. This phase is the longest, lasting anywhere from two to five years.
    4. Remodeling Phase: The newly formed bone reshapes into its final mature form.

    Symptoms

    Early diagnosis is crucial for a positive outcome. Parents should be aware of both early and late signs of the disease. Early Symptoms

    • A limp: This is often the first and most prominent sign sometimes appearing before the child complains of any pain.
    • Hip, thigh, or knee pain: Pain can be felt in the hip but may also be referred to the knee, thigh, groin, pelvis, or abdomen. This is often worse with movement.
    • Limited range of motion in the hip joint.
    • Muscle cramps or spasms in the muscles surrounding the hip.

     

    Later Symptoms

    • Abnormal walking pattern: This may be described as a Trendelenburg gait, which indicates weakness in the hip muscles.
    • Muscle atrophy: One thigh or buttock may appear smaller than the other.
    • Uneven leg lengths: The affected leg may appear shorter.

     

    Diagnosis

    Diagnosis of Perthes Disease is made through a physical examination and imaging tests. An X-ray can show evidence of the disease’s stage and severity, while an MRI may be used for a more detailed view.

    Treatment and Management

    Treatment plans are highly personalized and depends on several factors: your child’s age, the stage and severity of the disease, and how much of the bone is affected. The goals of treatment are to reduce pain, maintain hip motion, and ensure the femoral head heals in a round normal shape to prevent long-term complications like arthritis. Younger children (under 6 years old) with mild cases often have better outcomes with less invasive treatments, as their bones heal more quickly.

    Non-Surgical Treatments:

    • Observation: Regular follow-up appointments for very young children with mild cases.
    • Activity Restrictions: Avoiding high impact activities like running and jumping is essential to protect the hip joint.
    • Crutches or a walker may be used to reduce weight-bearing on the affected hip.
    • Physical Therapy: Exercises are essential to improve muscle strength, balance, and range of motion.
    • Medications: Over the counter anti-inflammatory drugs can help manage pain and inflammation.
    • Bracing/Casting: A Scottish Rite brace or a cast may be used to keep the hip in proper alignment and position which helps the femoral head heal properly.

     

    Surgical Treatments

    Surgery may be considered for older children or those with severe cases where non-surgical methods haven’t been effective.

    • Osteotomy: This procedure involves cutting and realigning the femur or pelvis to improve the containment of the femoral head within the hip socket.
    • Soft Tissue Procedures: These procedures may be performed to improve the hip’s range of motion.

    Recovery

    Recovery from Perthes disease can be a long process, often taking several years. With proper treatment most children recover completely and can return to their regular activities without long-term issues. A child’s age at diagnosis is a significant factor in their prognosis; the younger the child the better the chances of a full recovery.

    When to Seek Medical Attention

    Early diagnosis is crucial, as delayed treatment increases the risk of developing hip arthritis in adulthood. If your child begins to limp or complains of persistent pain in their knee, thigh, groin, or hip, it is highly recommended to schedule an appointment with a board-certified pediatric orthopedic surgeon.

    It is important to take your child to pediatric specialists who are experts in treating only kids. At Children’s Orthopaedic and Scoliosis Surgery Associates, LLP our board certified, fellowship trained, specialists provide the best child-friendly care using the latest cutting-edge technology that results in the safest and most accurate outcomes. Please call our office at (727) 898-2663 to schedule an appointment.

    Medically reviewed by Daniel C. Bland, MD Board Certified Orthopaedic Surgeon.

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