What is Transient Synovitis/Irritable Hips/ Toxic synovitis?

Transient Synovitis, Toxic Synovitis or Irritable Hip is a medical condition observed in children between 3-8 years that causes pain in the hip joint followed by limping. The underlying cause is the inflammation in the lining of the synovial joint. Although the condition is usually transitory, it may lead to Osteoarthritis in the later stages of life or may recur in case the child acquires infection.

Irritable hip is a transient condition in children that causes pain and a limp.

The pain ranges from mild to severe and tends to start suddenly. It usually occurs on one side of the hip, but it can affect the hip, groin, thigh, and knee on the affected side.

Children may develop a limp, and babies may crawl or cry in an unusual way because of the pain. This may be more noticeable while changing diapers.

A slight fever sometimes occurs, but this is less common. If a child has a fever of above 101ºF, they more likely have a different health problem that could be more serious.

What causes Transient Synovitis/Irritable Hips?

In acute transient synovitis, inflammation occurs in the synovial membrane that surrounds the hip. The underlying reason for this is not clear.

Possible explanations include:

A viral infection
The inflammation in the hip may be an allergic reaction that occurs when the immune system responds to infection elsewhere in the body.
About 2 weeks before the onset of irritable hip symptoms, the child may have had an upper respiratory tract infection or one that caused a cold, a sore throat, or diarrhea, for example.
A fall or another injury
A child may experience physical trauma before the symptoms of irritable hip become clear.

What is the diagnosis for Transient Synovitis/Irritable Hips?

The doctor, usually a primary care physician, will ask the child, parent, or caregiver about symptoms, and then perform a physical examination.

They may also order an imaging scan, such as an X-ray, or a blood test to detect infection.

Differential diagnoses

Some conditions cause symptoms similar to those of irritable hip, including:

Perthes disease: This can damage the head of the femur, or thighbone, by interrupting the blood supply to the hip.
Fracture or contusion: Either of these injuries to the hip can cause it to flare up.
A tumor in the hip: This can cause sensations similar to irritable hip.
Juvenile idiopathic arthritis: This involves chronic joint inflammation with an unknown cause that occurs in children under 16 years of age. It can affect the hip joint.

Other possible issues include septic arthritis and osteomyelitis.

Each can cause a very sick child to develop elevated C-reactive protein levels and sedimentation rates.

Sedimentation is the process through which red blood cells separate from blood serum, and it is part of the inflammation mechanism. The body sends out C-reactive protein in response to inflammation, which is why increased rates occur with irritable hip symptoms.

What is the treatment of Transient Synovitis/Irritable Hips?

The child should rest and not attend school or nursery groups. They should avoid any participation in sports until the pain completely disappears.

It may be most comfortable to lie on their back, with their knee bent and turned out, and the foot on the affected side turned out.

With rest, symptoms often start to resolve within 3 days, and they should be gone within 2 weeks, though they may last 4-5 weeks.

A child with irritable hip usually does not need to spend time in the hospital.

The doctor may recommend nonsteroidal anti-inflammatory drugs or acetaminophen for pain relief. Children under 16 years of age should not take aspirin.

If the condition does not resolve, or if the pain persists or gets worse, seek medical attention. Ongoing or increasing pain may indicate a different underlying condition.

What Else Should I Know?

Toxic synovitis/Irritable hip usually goes away within a week or two, but sometimes can last for 4-5 weeks.

While most kids have no long-term effects from it, some can develop toxic synovitis multiple times during childhood. If your child has a history of toxic synovitis, let your doctor know.