Legg-Calve-Perthes Disease or Coxa Plana: Causes, Risk Factors, Symptoms, Treatment, Exercises, Diagnosis

Legg-Calve-Perthes Disease is also called as Perthes Disease, Calve-Perthes disease, Coxa Plana, and Osteonecrosis of the femoral head.

Legg-Calve-Perthes Disease or Coxa Plana is a childhood disease that affects the head of the femur (the ball of the thigh bone at the hip joint) resulting in inadequate supply of blood to the epiphysis.¹ This creates weakness in the bone, which eventually breaks down very easily and dies.

The exact reason for this kind of blood vessel disease occurring in the femoral head is still not clear despite considerable research, as this disease is neither caused by injury nor by general blood vessel problem and a child with Perthes disease is otherwise healthy and does well.

The pelvis and thigh bone form a ball-and-socket joint. Legg-Calve-Perthes Disease or Coxa Plana is a condition, which occurs due to temporary interruption in the supply of blood to the femoral head by forcing the affected part to become weak and as a result the bone breaks down more quickly and smoothly. Legg-Calve-Perthes Disease or Coxa Plana affects the hip. Although, Legg-Calve-Perthes Disease usually affects only one hip, both the hips can also be affected in some cases. The recovering ability of the affected bone is very poor. However, the blood vessels may grow again over several months returning the blood supply to the necrosed or dead bone tissue and the femoral head starts to remodel correcting the deformity. This process is similar to healing of the common types of fractures, but takes a longer duration to heal completely.

The more the Legg-Calve-Perthes Disease progresses, the more the femoral head becomes weak and fractures by losing its pleasant round shape. Therefore, treatment of Legg-Calve-Perthes Disease or Coxa Plana concentrates on maintaining the ball part of the joint as round as possible during the healing process which may take couple of years or more. In few cases, the casts, exercises and physical therapy also help in holding the ball firmly in the socket. Surgery is also needed in rare cases, but in many cases of Legg-Calve-Perthes Disease, the patients recover without undergoing surgery.

Although Legg-Calve-Perthes Disease can affect children at any age, it is more commonly seen between the age group of 4 to 8 years.

Legg-Calve-Perthes Disease or Coxa Plana is caused due to lack of blood supply to the ball portion of the joint of the hip that is the femoral head forcing the bone to become unstable and weak and to break down easily, which later on recovers very poorly.² Although, the exact cause of this decrease in blood flow to the femoral head is still not known, some of the suspected causes of Legg-Calve-Perthes Disease may include:

• Age: Legg-Calve-Perthes Disease most commonly affects children in the age group of four to eight years.
• Sex: Boys are five times more prone to Legg-Calve-Perthes Disease when compared to girls.
• Race: Legg-Calve-Perthes Disease more commonly affects white children than black children.
• Family History: Legg-Calve-Perthes Disease is seen to run in families in few of the cases.

• Stiffness or pain in the thigh, knee, hip and groin.
• Gradual worsening of limping.
• Decreased range of motion of the affected hip.
• Stiffness in the affected hip.
• The affected leg may look shorter than the healthy leg.
• The affected leg may also become slightly thinner eventually due to the thinner thigh muscles because of less usage when compared to thigh muscles in the healthy leg.

The treatment for Legg-Calve-Perthes Disease or Coxa Plana usually concentrates on keeping the femoral head as round as possible in order to help the hip to function appropriately. The socket works like a mold for the fractured femoral head during the healing process. There are many treatment options available for keeping femoral head snug in the socket of the joint. The healing time varies with each patient depending upon the severity of the affected bone. The treatment process usually takes couple of years or more.

If the patient is less than seven years of age and the femoral head is still round in shape, then the helpful nonsurgical treatments for Legg-Calve-Perthes Disease may include.

Rest: Decreasing the amount of stress and weight on the affected bone helps in slowing down the damage caused due to Legg-Calve-Perthes Disease.³ Restricting heavy amount of physical activity and using crutches may help in keeping the weight off from the affected joint.

Traction: Episodes of traction and bed rest are also helpful to treat severe pain.

Casting: As it is important to keep the femoral head in its socket, a special kind of leg cast is also used in order to keep both the legs spread widely apart for about four to six weeks of duration.

Exercises: Stretching and strengthening exercises help in keeping the hip more flexible. Exercises not only help in improving range of motion and muscle strength, but also maintain the balance and coordination of the joint.

Surgery: Surgery is performed only when nonsurgical treatments fail to work appropriately for Legg-Calve-Perthes Disease.³ This usually happens in case of patients above seven years of age. This may also work for children suffering with more severe bone deformities. Surgeries may include:

Contracture Release: Legg-Calve-Perthes Disease and the periods of immobility during treatment can shorten some of the nearby tendons and muscles, which can cause the hip to pull inward forming a contracture. Surgery may be required to lengthen out these tissues and help restore normal flexibility of the hip joint.

Loose Body Removal: In few cases, the damage to the femoral head leads to loosing bits of bone or tearing of cartilage flaps. Surgery may be required to remove these bits of tissues and help the hip joint to function smoothly.

Hardware Implants: Hardware implants are placed when leg casts fail to keep the ball and socket in correct position due to which changing ball and socket position becomes necessary. Hardware implants may include plates, wires, and screws.

Physical Therapy: Physical therapy for Legg-Calve-Perthes Disease is important in speeding up the healing process and obtaining optimal results. Physical therapy also decreases the likelihood of recurrences in the future. Physical therapy may include:

• Joint mobilization.
• Exercises to improve strength and flexibility.
• Activity modification and training.
• Appropriate plan for return to activity.
• Hydrotherapy.

Beneficial exercises for Legg-Calve-Perthes Disease or Coxa Plana concentrate on internal rotation, external rotation, abduction, adduction, flexion and extension of the hips. Abduction exercises move the leg away from hip whereas adduction exercises are performed by bringing the hip closer to the mid line of the body. Internal and medial rotation is performed by turning the toes in toward the center of the body and external or lateral rotation is performed by moving the toes outward. Flexion is caused when knees are bent toward the hips whereas extension exercises helps in straightening the legs. These exercises are also performed by lying on a bed and exercise mat in order to keep the weight off the hip joints. Swimming may prove to be a good exercise as it not only strengthens the muscles, but also provides range of motion exercises while water helps in supporting the body weight.

Exercises, contact sports and activities that involve jumping or running or activities that place weight on the hips should be strictly avoided as they may worsen the condition.

A complete subjective and physical examination is performed to diagnose Legg-Calve-Perthes Disease. A physician will move around the affected leg in order to examine the pain. A leg is also rotated in different positions in order to check for reduced range of motion.

• Magnetic resonance imaging (MRI).
• X-rays.
• Bone scan.

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