Transient synovitis: What parents should know – CHOC

What is transient synovitis?

Transient synovitis can be unpleasant for a child and unsettling for parents – especially when symptoms start suddenly. The good news is it causes no long-term problems. Here, Dr. Reshmi Basu, a CHOC pediatrician, provides an overview of the condition.

Transient synovitis – also known as toxic synovitis – is the temporary inflammation of the hip that can cause limping and pain in the hip and leg. Transient synovitis usually goes away within a week or two.

What causes transient synovitis?

Doctors don’t know the exact cause of transient synovitis, but some children can develop it after having a viral infection, such as a cold or diarrhea. This is why some doctors think transient synovitis is caused by substances made by the body’s immune system to fight infection.

Transient synovitis can happen at any age, but is most common in kids between the ages of 3 and 8 years. It’s also more common in boys.

Sometimes transient synovitis can be confused with septic arthritis, or infectious arthritis. This is a more serious condition caused by a bacterial infection that invades the joints and can cause long-term joint damage. Doctors can rule out septic arthritis or other conditions through a physical exam and diagnostic tests.

What are the signs and symptoms of transient synovitis?

When kids have transient synovitis, the pain starts suddenly and usually is only on one side of the body.

Other signs to look for include:

• a recent viral infection, such as a cold or stomach virus;
• low-grade fever (up to 101°F);
• limping with toes turned outward, the knee bent or straightened;
• walking on tiptoes;
• hip discomfort after a long period of resting the joint (such as sitting in a car or at a desk, or watching TV);
• knee or thigh pain with no hip pain;
• in younger children, crying; or
• in some cases, a refusal to walk.

The most common signs of transient synovitis  in babies are abnormal crawling and crying. They might also cry when their hip joints are being moved, such as during diaper changes.

How Is transient synovitis diagnosed?

The first thing a pediatrician will do is examine your child to see what kind of movement is painful. They’ll move the knee, hip and other joints. This is to confirm that the limping is caused by joint pain.

Next, the pediatrician may order an ultrasound of the hip. This imaging test will show whether there is fluid in the hip joint. Fluid means there is swelling and inflammation of the tissues. The pediatrician also may do blood tests to see how much swelling there is.

Sometimes, the blood test results make it hard for the doctor to rule out septic arthritis. In that case, fluid might be taken from the joint for a lab test to detect bacteria. This is called a culture. The physician also may do other tests and X-rays to look for or rule out other potential causes of your child’s limping and pain.

How is transient synovitis treated?

Treatment for transient synovitis usually includes anti-inflammatory drugs such as ibuprofen or naproxen. Your child may take these for up to 4 weeks until the inflammation goes away. The doctor also may recommend medicine for pain, such as acetaminophen.

It’s important to rest the hip joint and avoid putting weight on it during recovery. Children can usually walk again comfortably within a day or two of taking the anti-inflammatory medicine.

However, participation in activities like gym class or sports will have to wait until your child fully recovers.

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