Perthes Disease

What is Perthes disease?

Perthes disease is a rare kind of disability, primarily affecting the hip joint of children. It is characterized by the softening and ultimate breaking down of the top part of the thigh bone, called the femoral head. This form of osteochondritis is also called Calvé-Legg-Perthes disease after each of the three doctors who first described it in 1910.

What Causes Legg‑Calve‑Perthes disease

The condition occurs when small blood vessels suddenly stop supplying blood to the femoral head. What exactly causes this disruption is not known, but a number of studies show that certain factors may be associated with it such as:

• Blood Clotting: Disturbances in the formation of blood clot in the artery called, ligamentum teres femoris, may result in an insufficient blood supply to the femur.
• Direct Trauma: Blood vessel damage caused by trauma may affect the femoral head and hip joint.
• Constriction of Femoral Artery: This may lower blood supply to the medial femoral circumflex artery, the main blood vessel supplying blood to the femoral head.

Risk Factors

Age: Although the disorder may affect children of nearly any age, it is most common in between ages 4 and 8.

Gender: It is up to five times more common in boys than in girls.

Race: It is more common among Caucasian children.

Family History: In a few cases it seems to be hereditary, but there is a lack of evidence to prove it.

Socioeconomic Class: Its occurrence is high among those belonging to lower social classes.

Apart from these, certain diseases like transient synovitis, and some endocrine disorders may also lead to the condition.

Stages of Perthes disease

The lack of blood supply to the femur, results in a number of changes in the bone structure that show up in four clear stages.

1. Necrosis: During this early stage, lasting for several months, the bone cells of the affected area die.
2. Fragmentation: Occurring over a period of 1 to 2 years, the body replaces its dead bone with a softer one. This bone, being weaker, may fracture or become distorted easily.
3. Re-ossification: In this longest stage, lasting for a few years, stronger new bone cells begin to grow in the femoral head.
4. Healed: The bone growth is complete, with the femoral head attaining its final shape.

Complications

• Lower back pain
• ADHD
• Hinge abduction

Perthes disease Complication in Adults

• Hip arthritis
• Osteoarthritis

Signs and Symptoms

The earliest symptom constitutes a change in the manner a child walks or runs. The standard gait variations observed are:

• Occasional limping
• Stiffness and limited range of motion in the hip joint
• A peculiar running style

Another prominent symptom is pain, and it entails the following characteristics:

• Areas Affected: Either one hip (unilateral) or both hips (bilateral), groin, thigh or knee (known as referred pain)
• Features: Worsens with activity and relieves with rest

Other Symptoms

• Muscle spasms
• Shortening of the affected leg
• Thinner thigh muscles
• Fever

Depending upon a child’s activity level, the symptoms occur intermittently over a period of weeks to months, and mostly affect one hip. Both hips are affected in only 10% to 15% of all cases.

Diagnosis and Tests

The diagnosis generally involves:

• Physical examinations to assess a child’s range of movement in the hip
• X-rays of the hip joint
• Bone scan to determine the disease (if in the earlier phase, an X-ray picture comes normal, but symptoms persist)
• MRI scans to check the extent of damage.
• Blood tests to rule out problems like an infection and also to determine levels of calcium, vitamin D, and boron as these play a vital role in strengthening bones.

Differential Diagnosis

• Multiple epiphyseal dysplasia
• Spondyloepiphyseal dysplasia
• Sickle cell disease
• Gaucher disease
• Hypothyroidism
• Meyers dysplasia

Treatment and Management

Treatment mainly aims at restoring normal hip movement, ensuring that the femoral head remains well seated in the hip socket and relieving inflammatory symptoms. It can be treated by various means, but before treatment, these factors are evaluated:

The Age of the Child: As young children, (age 6 and below) tend to recover fast by growing new, healthy bones, thereby requiring no treatment.

The Extent of Damage to the Femoral Head: As the possibility of regrowth without deformity is reduced if the disorder damages more than 50% of the femoral head.

Older children and those with over 50% of damage usually need surgical intervention.

Nonsurgical Treatment for Small Children (2 to 6 years)

Observation and Physiotherapy

Firstly, a child is monitored with the help of x-rays so as to determine if the femoral head is regrowing properly. Then, he is given a home exercise routine to follow, with exercises like hip abduction and hip rotation that, focussing on internal rotation and reducing stiffness, may help in recovering the range of motion of the hip joint.

Anti-inflammatory Medications

Anti-inflammatory medicines, such as ibuprofen, and acetaminophen (Tylenol) may lessen inflammation. Depending on the stage of the disorder, these may be recommended for several months.

Crutches and Traction

Some children may require crutches for a short time to prevent too much pressure on the affected hip, while those with severe pain may need a period of bed rest. Traction is also done by placing pulling forces on the femoral head so as to relieve the tension existing between it and the hip bone.

Casting and Bracing

A leg cast is used in case a deformity is indicated by x-rays, or if the range of motion becomes restricted. At first, both legs need to be kept spread apart for nearly four to six weeks so that the femoral head remains in its place, within the hip socket (acetabulum). After this, hip flexibility is maintained by using a night-time brace. Physical exercises are resumed after the cast is removed. Leg braces ensure maximum mobility by providing external support to the hip and leg.

Orthoses

These orthopedic devices help to maintain a normal anatomic position of the leg and hips by promoting the femur’s internal rotation.

Follow up Measures to Take at Home

• Remodeling of Activity: High-impact actions, like running, bouncing or jumping should be avoided
• Administration of Heat or Cold: Hot packs or ice may help in relieving hip pain associated with the disease

Surgical Treatment for Older Children (above 8 years)

The three intended outcomes of surgery involve:

1. Reestablishment of proper alignment of hip bones
2. Restoration and maintenance of the femoral head
3. Improvement of the shape of hip joint so as to prevent arthritis in later age

Osteotomy

This is carried out by cutting and repositioning the femoral or pelvic bone by changing the femoral head’s position or deepening the socket, using pins or plates, so that the femoral head remains within the acetabulum. After the procedure is over, a cast is used for 6 to 8 weeks to protect the joint.

Removal of Loose Bodies or Excess Bone

Torn flaps of cartilage or lose parts of bones around the femoral head are removed so as to ease movement as well as relieve pain.

Hip Distraction

In children with severe symptoms, a device, known as external fixator is attached to the outside of the hip through a process called distraction osteogenesis. This device reduces joint compression, thereby allowing it to heal without damaging tendons or ligaments.  Since stability is provided after being kept in position for three to six months, children can walk, even wearing the external fixator.

Hip Replacement Surgery

In this surgery, the hip ball is replaced within the socket.

According to several studies, the disability may also be controlled through Ayurvedic treatment, but more research needs to be done to validate this.

Prognosis and Long Term Effects

With regrowth of the femoral head, the hip joint becomes normal in most cases, starting to work well within about two years. However, if it does not reform properly and attains a flat shape, stiffness or other hip problems may happen later in life.

Can Perthes disease be Prevented

The disability cannot be prevented, but certain measures can be taken to maintain a proper bone health:

• Optimum Exposure to Sunlight: Exposing one’s hands and face to sunlight for about 15 minutes per day, naturally influences the body to make vitamin D; the chief nutrient that ensures calcium is absorbed and employed by the body.
• Healthy Nutrition: Having a healthy diet is necessary for maintaining proper weight and minimising bone loss.

Incidence

It is estimated that this disorder affects 1 in 10,000 children per year.

Perthes disease ICD-9-CM Codes and ICD-10-CM Codes

The ICD-9-CM code of Perthes disease is 732.1, and the ICD-10-CM code is M91.1.