ALL YOU NEED TO KNOW ABOUT LEGG–CALVÉ–PERTHES DISEASE: SYMPTOMS, CAUSES, AND TREATMENT

Legg–Calvé–Perthes disease (LCPD) is a rare hip disorder that affects children, usually between the ages of 4 and 10. Also known commonly as Perthes disease, it occurs when the blood supply to the head of the femur (the ball part of the hip joint) is disrupted, causing the bone to die and break down. In the affected hip, this may result in discomfort, stiffness, limping, and decreased range of motion. LCPD can also affect the shape and function of the hip joint, increasing the risk of osteoarthritis and other complications later in life.^[1]

In this blog, we will discuss the symptoms, phases, causes, diagnosis, treatment, prevention, and outlook of LCPD.

Symptoms of LCPD

The condition mostly affects the femoral head, or ball portion of the hip joint, and the acetabulum, which is the cup part of the hip joint that holds the femoral head. The femoral head becomes weak and fractures easily, and can lose its round shape. The acetabulum can also become shallow and irregular and may not fit well with the femoral head. This can lead to any of the following Perthes symptoms:

• Pain in the hip, groin, thigh, knee, or ankle. The pain may be mild or severe and may worsen with activity and improve with rest.
• Limping or difficulty walking. The child may walk with a limp or have a waddling gait, especially when tired or after prolonged activity. The child may also have trouble running, jumping, or climbing stairs.
• Reduced range of motion of the hip joint. The child may have difficulty moving the hip in certain directions, such as turning the leg inward or outward.
• Muscle weakness or wasting. The child may have reduced muscle strength or size in the thigh or buttock of the affected side due to disuse or inflammation of the hip joint.
• Leg length discrepancy. The affected leg may become shorter or longer than the other leg due to bone loss, depending on the degree of bone loss or growth disturbance.

The symptoms of LCPD may vary depending on the stage and severity of the disease, as well as the age and activity level of the child. Roughly 10-20% of children with the condition develop it in both hips.

The symptoms of LCPD may come and go over several months or years, depending on the healing process of the bone. The symptoms may also be more noticeable during cold or humid weather or during periods of growth spurts. It is usual for symptoms to vary from child to child, depending on their age, activity level, and individual response.

What is the difference between LCPD and Perthes disease?

LCPD and Perthes disease are two names for the same condition. LCPD is the medical term that describes the disease process, while Perthes disease is the eponym that honors the doctors who first described the condition: Arthur Legg, Jacques Calvé, and Georg Perthes.

Avascular Necrosis vs Legg Calve Perthes: What’s the difference?

LCPD and avascular necrosis (AVN) are both conditions that involve the death of bone due to reduced blood supply. However, LCPD is a specific type of AVN that affects only the femoral head in children, while AVN can affect any bone in any age group. LCPD is also a self-limiting condition that goes through phases of bone death, breakdown, and regeneration, while AVN is a progressive condition that leads to permanent bone loss and collapse.

Phases of LCPD

LCPD is a progressive disease that goes through four main phases: Necrosis, Fragmentation, Reossification, and Remodeling. Each phase may last from a few months to a few years, depending on the child and the extent of the bone damage.^[2] In most cases, the disease usually resolves within 2-3 years or by the time the child reaches puberty, with a good lifelong prognosis.

The four phases are:

• Initial phase (Synovitis or necrosis phase). This is the phase when the blood supply to the femoral head is interrupted, causing the bone to die. This phase may last from a few weeks to several months and is usually asymptomatic or mildly symptomatic. The bone may appear normal or slightly flattened on x-rays.
• Fragmentation phase. This is the phase when the dead bone begins to break down and collapse, causing the femoral head to lose its round shape and become irregular. This phase may last from 6 - 12 months and is usually the most symptomatic and painful phase where the child has a reduced range of motion. The bone is brittle and may appear broken, fragmented (with holes), or deformed on x-rays. Swift treatment is needed to keep the ball in the hip socket and to prevent the ball from collapsing with permanent consequences. The child is at a high risk of fractures during this phase.
• Reossification phase (reconstitution phase). This is the phase when the blood supply to the femoral head is restored, and new bone begins to form and replace the dead bone. This phase may last 2 - 3 years while the hip socket fills with new bone. It is usually less symptomatic and painful than the previous phase. The bone may appear patchy or mottled on x-rays. In severe forms of Perthes hip disease, the ball may grow back irregularly or larger than the hip socket. This can manifest roughly 18 months after the first symptoms appear.
• Healing phase (residual phase). This is the phase when the bone healing process is completed, and the femoral head regains some of its shape and function. This phase may last indefinitely and is usually asymptomatic or mildly symptomatic. The bone may appear normal or slightly flattened on x-rays. A fraction of patients develop irregular or oval-shaped balls of the hip, which can lead to arthritis in approximately 50% of patients later on in life.

The goal of treatment is to preserve the shape and function of the hip joint as much as possible to prevent deformity, especially during the fragmentation and reossification phases, when the bone is most vulnerable.

Causes of LCPD

Despite being discovered over 100 years ago and even found in ancient bone remains all over the globe, the exact cause of LCPD is unknown. It is thought to be connected to a brief interference in the blood supply to the femoral head, which may be triggered by various factors, such as:

• Hip joint trauma or injury brought on by a fall, blow, or twist.
• Infection or inflammation of the hip joint, such as septic arthritis, osteomyelitis, or synovitis.
• Genetic or metabolic disorders, such as sickle cell anemia, Gaucher disease, or rare blood clotting illnesses.
• Idiopathic or unknown factors, such as abnormal blood vessel growth, blood clotting issues, or suppressed immune function.

In rare instances, mutations in the COL2A1 gene^[3] have been associated with similar bone loss (avascular necrosis) occurring to the head of the thigh bone in children. Several other genes have been implicated, yet these correlate towards potential underlying health conditions such as blood clotting issues, and there are no finite conclusions have been drawn as of yet.

How rare is LCPD?

LCPD is a rare hip disorder that affects about 0.4-29 in 100,000 children worldwide. It is more common in boys than in girls. It can affect one or both hips, yet it is more common in one hip.

LCPD Risk Factors

LCPD is not contagious and is not caused by poor nutrition, lack of exercise, or environmental factors. However, some risk factors may increase the likelihood of developing LCPD, such as:

• Blood clotting disorders. These include hypofibrinolysis (inhibited ability to form blood clots) and thrombophilia (greatly increased blood clotting activity). Up to 75% of patients experience some form of blood clotting issue.^[4]
• Age. LCPD is most common in children between the ages of 4 and 10, although it can occur in children as young as 2 or as old as 15. The likelihood that the hip joint will mend in a normal shape is higher in younger children at the time of diagnosis.
• Gender. LCPD is more common in boys than in girls, with a ratio of about 4:1. Boys also tend to have more severe and bilateral cases than girls.
• Family History. LCPD may have a genetic component, as some cases have been reported to run in families or to be associated with certain gene mutations. However, the exact genes and inheritance patterns are not well understood.

How is LCPD Diagnosed?

LCPD is usually diagnosed by an orthopedic specialist or surgeon who specializes in the treatment of musculoskeletal disorders. The diagnosis is made based on the child’s medical history, physical examination, and imaging tests.

The first sign is often pain, as well as a misaligned walking gait. It may be delayed or missed in the initial phase when the femoral head loses blood circulation, causing the hip joint to become painful, rigid, and irritated and the bone becomes mostly composed of dead tissue. Therefore, it is important to consult a doctor if the child has any symptoms of hip pain, stiffness, limping, or reduced range of motion.

Some imaging tests used to diagnose Legg-Calvé-Perthes disease follow^[5]:

• X-rays. This is the most common and useful imaging test for LCPD, as it can show the changes in the shape and structure of the femoral head and the hip joint. An x-ray of Legg-Calve Perthes disease can also help determine the stage and severity of the disease and monitor the progress of treatment.
• Magnetic resonance imaging (MRI). MRI is more sensitive and detailed than x-rays, as it can show the blood flow and the soft tissue structures of the hip joint, such as the cartilage, the ligaments, and the muscles. MRI can also help detect the early signs of bone death before they might be visible on x-rays and rule out other possible causes of hip pain, such as infection or tumor.
• Bone scan. A bone scan is a nuclear imaging test that uses a radioactive tracer to measure bone metabolism and activity. These can also be used to help detect the early signs of bone death before they are visible on x-rays and assess the extent and distribution of bone damage.

Other tests, such as blood tests, urine tests, or genetic tests, may be done to check for any underlying conditions or disorders that may be associated with LCPD, such as infection, inflammation, rare genetic diseases, or metabolic problems.

Perthes Disease Treatment

LCPD is treated with non-surgical or surgical methods, depending on the child’s age, the stage and severity of the disease, and the shape of the femoral head.

The main goals of Legg-Calvé-Perthes disease treatment are to:

• Relieve pain and inflammation
• Maintain or improve the range of motion of the hip joint
• Prevent or correct the deformity of the femoral head
• Preserve or restore the normal function of the hip joint
• Stifle or delay the development of osteoarthritis

Perthes disease treatment options include^[6]:

Non-Surgical Treatments

Non-surgical treatment is the first-line and most common treatment for LCPD, especially for mild and early cases. Non-surgical treatment often involves the following:

• Medications. Medications, such as nonsteroidal anti-inflammatory drugs (NSAIDs) may be prescribed to reduce pain and inflammation. However, medications should be used cautiously, with the dosage monitored and adjusted as needed by a doctor to avoid side effects.
• Physical therapy. Physical therapy, such as exercises, stretches, or massages, may be done to maintain or improve the range of motion, strength, and flexibility of the hip joint. Physical therapy may also help prevent stiffness and reduce pain levels. At other times, bed rest is recommended for pain relief and optimal bone recovery. These measures are encouraged over other forms of non-surgical treatment, such as orthotics unless the situation deems them beneficial.
• Orthotics, such as braces, splints, casts, or crutches support, protect, or immobilize the hip joint and prevent or correct deformity. The vast majority of patients do not require orthotics and outcomes tend to be better with physical therapy unless hip joint collapse is imminent. They may also need to take special precautions to accommodate for differences in leg height. Some patients benefit from a wheelchair.
• Traction, which involves applying a gentle and continuous pull on the leg to relieve pressure and pain in the hip joint.

Surgical Treatments

Surgery is usually performed to retain the shape and function of the hip joint and lower the risk of arthritis or total immobility later in life. Not all with Perthes disease require surgery. Surgical options include:

• Osteotomy, which involves cutting and reshaping the bone of the femur or the pelvis to improve the alignment and fit of the hip joint.
• Osteochondroplasty^[7] involves removing or reshaping the damaged or deformed part of the femoral head to restore its roundness and smoothness.
• Core decompression^[8] involves drilling small holes in the femoral head to relieve pressure and stimulate blood flow and healing.
• Bone grafting^[9] involves transplanting healthy bone from another part of the body or from a donor to fill the gaps or defects in the femoral head.
• Joint replacement involves replacing the damaged or worn-out hip joint with an artificial one made of metal, plastic, or ceramic. This is usually reserved for older children or adults who have severe pain or disability due to LCPD.

The choice of treatment for LCPD depends on several factors, such as the child’s age, the stage and severity of the disease, the shape of the femoral head, the preference of the doctor and the family, and the availability of resources. The doctor will discuss the benefits and risks of each treatment option with the child and the family and help them make an informed decision.

Prevention of LCPD

There is no known way to prevent LCPD, as the cause of the blood flow disruption is unknown. However, some possible ways to reduce the risk or severity of LCPD include:

• Avoiding trauma or injury to the hip, such as falls, blows, or twists.
• Seeking prompt medical attention for any signs of infection or inflammation of the hip, such as fever, redness, swelling, or warmth.
• Having regular check-ups and blood tests for any conditions that affect blood circulation, such as sickle cell anemia, thalassemia, or vasculitis.
• Maintaining a healthy weight and a balanced diet prevent obesity and malnutrition, which may affect bone growth and development.
• Limiting or modifying activities that put excessive stress or strain on the hip joint, such as running, jumping, or contact sports.

Prognosis and Outlook of LCPD

The outlook of LCPD depends on several factors, such as the child’s age, the stage and severity of the disease, the shape of the femoral head, and the type of treatment. Some studies suggest that the outcome for 60-80% of patients is good, resolving within 2-3 years without too many problems cropping up later in life.^[10]

LCPD may affect the child’s later life in various ways, depending on the outcome and complications of the disease. Some children may have no or minimal problems, while others may have persistent or residual symptoms, such as:

• Persistent pain, stiffness, or limping in the affected hip
• Decreased range of motion or function of the hip joint
• Leg length discrepancy or gait abnormality
• Growth disturbance or deformity of the femur or the pelvis
• Osteoarthritis or degenerative hip disease in younger patients
• In adults, avascular necrosis or osteonecrosis of the femoral head

Ongoing care or additional interventions, such as joint replacement for osteoarthritis or degenerative hip disease may be required. Therefore, it is important for children with LCPD and their families to have regular follow-ups and consultations with their doctor and to seek support and guidance from other health professionals, such as physical therapists, orthotists, psychologists, or social workers.

Conclusion

LCPD is a rare hip disorder in children that causes the femoral head (the ball part of the hip joint) to die and break down due to reduced blood flow. This leads to pain, stiffness, limping, and reduced range of motion in the hip. It can also affect the shape of the hip joint and the risk of osteoarthritis. LCPD is diagnosed by medical history, physical examination, and imaging tests. The treatment aims to relieve pain and inflammation, maintain or improve hip function, and preserve or restore hip shape. The outcome depends on the child’s age, the disease stage and severity, and the treatment type. LCPD requires a multidisciplinary approach and a long-term follow-up to achieve a satisfactory and functional hip joint and a good quality of life.

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