Hip pain in children

What is it about ?

The hip joint is made up of the head of the femur which is round and fits into a cavity formed by the bones of the pelvis. The head of the femur is connected to the body of the femur through the neck of the femur.

Hip pain in a child can follow an accident, but it can also be due to an illness, trivial or serious, for example:

• A hip synovitis (also called “transient coxitis” or “hip cold”); it is an “aseptic” inflammation of the membrane that lines the hip joint. “Aseptic” means there is no bacterial infection. The disease is usually mild and occurs in children between 3 and 10 years old. Symptoms resolve spontaneously within 3 to 10 days. We do not know the origin. An injury or viral infection may be playing a role. At first, the symptoms may also suggest a serious hip disease, such as Legg-Calve-Perthes disease, rheumatism, or a bacterial infection of the hip.
• The Legg-Calve-Perthes disease is a blood flow disorder in the bone core of the head of the femur. The bone nucleus is the part of the bone where bone growth takes place. Due to insufficient blood supply, the bone in the head of the femur weakens, causing it to deform and sag. The disease usually affects children between the ages of 5 and 9. The most significant deformity occurs when the disease appears between the ages of 4 and 6 years.
• THE’epiphysis of the hip, also called epiphysis of the head of the femur, corresponds to the sliding of the upper part of the head of the femur out of the joint. This may result in displacement of the head of the femur relative to the neck of the femur. This can happen acutely, for example in an accident, or gradually, as the connection between the head of the femur and the neck of the femur weakens. Hip epiphysis is rare before the age of 10. Epiphysiolysis of the hip increases the risk of late osteoarthritis of the hip joint.

In whom and how often do these diseases occur?

• The synovitis is the most common cause.
• The Legg-Calve-Perthes disease is 4 times more common in boys than in girls.
• THE’epiphysis occurs in older children and adolescents, usually between 10 and 16 years old; in girls, it usually occurs a little earlier than in boys. It is 2.5 times more common in boys than in girls. There seems to be a link with obesity.

How to recognize it?

All of these illnesses cause pain and the child limps (lameness). Support on the affected side is then more difficult, and mobility is limited.

In case of hip synovitis, the pain is in the groin and the front of the thigh up to the knee. The pain starts suddenly and is usually mild. Lameness is the main symptom. An important element is the absence or presence of fever. Fever may indicate septic arthritis (due to a germ) of the hip. It is an infection that should immediately be followed by a doctor.

In the case of Legg-Calve-Perthes disease, the symptoms are at first very limited, and there is only a slight difficulty in walking. The child is dragging his leg a little. It is only later that the child complains of pain and really begins to limp. The pain is located between the groin and the knee. In children 4 to 6 years old, hip deformities can lead to permanent lameness. The disease usually lasts two to four years, then resolves spontaneously. Once in 10, both hips are affected.

In case of’epiphysis, about 3 in 10 children have pain in both hips. Vague pain and a feeling of stiffness in the hip, groin and upper leg are typical of this disease, initially only during or after physical activity (sport). The symptoms gradually increase, and the child begins to limp. The sudden sliding of the head of the femur is usually accompanied by throbbing pain and marked lameness. The intensity of the pain is variable: some children have almost no pain, while in others the pain is so intense that they no longer walk. It is sometimes very difficult to know where the pain is precisely: in the knee, thigh or groin. Epiphysiolysis in children is usually characterized by the fact that the legs are turned slightly outward from the upper body.

How is the diagnosis made?

The doctor begins primarily by listening to the history of symptoms:

• How did the symptoms (pain, lameness …) start? Is there an accident causing the problem? Did it happen suddenly or gradually?
• Has your child been ill recently?
• Does the child have a fever?
• Is the pain permanent? Do you notice a connection with periods of rest, exertion or sport, a poorly cured disease?
• Does your child complain of pain? Is there pain at rest?

The diagnosis of hip synovitis is posed from the story and the clinical examination. During this examination, the doctor not only pays attention to the affected hip, but also examines the other side and possibly the other joints. Hip movement is restricted in some directions, but not in all.

If necessary, an ultrasound can confirm that it is an inflammation of the membrane of the hip joint. X-ray examinations are always normal for hip synovitis and are not requested until symptoms persist or when the doctor is in doubt about the diagnosis. In the event of a blood test, the inflammatory parameters may be slightly increased.

The doctor will refer you to a specialist in the following cases:

• Symptoms last more than two weeks;
• The child is less than 2 years old or more than 10 years old;
• The presence of fever;
• Inflammatory parameters in the blood are greatly increased.

What can you do ?

If your child complains of pain in his hip, groin, thigh or knee, or if he is limping, it is best to see your GP. The latter can assess the cause and, if necessary, refer you to a specialist for further examinations.

In a child with hip pain or limping, the hip should be relieved immediately. Most cases of synovitis improve already after 3 days of bed rest. Worsening of symptoms despite rest is always suspicious. In this case, it is a question of taking this problem seriously.

What can the doctor do?

The hip synovitis resolves spontaneously, but to relieve symptoms the doctor will start treatment with paracetamol or an anti-inflammatory drug. If the doctor is also thinking about the possibility of septic arthritis, he may consider a puncture of the joint. This examination is performed in the hospital under anesthesia.

In the Legg-Calve-Perthes disease, the orthopedist corrects the position of the head of the femur and restores its spherical shape. To do this, he uses an abduction orthosis, the hip being kept in a spread position or he performs a surgical operation. Sometimes arthrography is needed. This is an x-ray under general anesthesia with the injection of a contrast product into the joint. The orthopedist thus obtains a good picture of the condition and can clearly visualize the way in which the operation is to be carried out. Then, every three months, he will do a clinical check-up of the hip and take x-rays until recovery is complete.

THE’epiphysis of the head of the femur is always treated during surgery. Usually, an attempt is made to stabilize the femoral head by means of a screw. The result of this operation depends on the size of the possible slip of the head of the femur relative to the neck of the femur.

Want to know more?

• Femur (image) – Larousse

• My child is going to have an ultrasound – Plaster

• Paracetamol – CBIP – Belgian Center for Pharmacotherapeutic Information
• Non-steroidal anti-inflammatory drugs – CBIP – Belgian Center for Pharmacotherapeutic Information
• My child is going to be operated on under general anesthesia – Plaster

Source

Foreign clinical practice guide ‘Hip pain in children’ (2000), updated on 08.08.2016 and adapted to the Belgian context on 23.06.2019 – ebpracticenet