Transient Synovitis

Transient synovitis, or toxic synovitis, is swelling and inflammation around your synovial membranes. Synovial membranes are tissues that surround your joints. “Transient” means it doesn’t last long before it goes away. In children, transient synovitis frequently affects the hip joints. The condition is the most common cause of hip pain in children.

The age range for transient synovitis is between 3 and 10 years old. Sometimes, it happens in kids younger than 3. The condition occurs more often in boys. It usually only affects one hip (more commonly, the right hip).

Other names for transient synovitis (pronounced “sin-uh-VIE-tis”) include:

• Transient synovitis of the hip
• Transient hip
• Irritable hip
• Synovitis hip

No one wants to see their child experience pain. But rest assured, transient synovitis isn’t a serious condition. With rest and supportive care, your child should feel better within a week or two.

Toxic synovitis symptoms

The main symptom of toxic synovitis is hip pain. The pain may come on slowly — your child may not even notice it at first. Other times, it happens quickly. The pain may cause your child to:

• Have problems standing
• Have trouble walking
• Walk with a limp

Some children experience thigh or knee pain instead of hip pain.

What causes transient synovitis?

Researchers don’t know what causes transient synovitis. But they’ve noticed that the condition often occurs following upper respiratory infections. It frequently shows up after your child has had symptoms of the common cold, vomiting or diarrhea. They’ve also found that toxic synovitis sometimes happens after:

• Bacterial infections
• Trauma
• Allergic reactions

Complications of transient synovitis of the hip

The main complication of transient synovitis is the chance of the condition coming back (recurring). Transient synovitis recurs in up to 2 in 10 cases. But this may happen because children return to their normal activities too soon.

In up to 1 in 10 cases, a condition called Legg-Calve-Perthes disease (LCPD) can occur. LCPD is a condition that causes your child’s hip bones to break down and then regrow. This can change the shape of your child’s hip bones.

How doctors diagnose transient synovitis

Your child’s healthcare provider will ask about your child’s symptoms and medical history. They’ll want to know about any recent infections or trauma.

Your child’s provider will also do a physical exam. They’ll check the range of motion in your child’s hip joint. They want to see what kind of movement makes their pain worse.

Tests that are used

Providers don’t use a specific test to diagnose transient synovitis. Depending on their assessment, they may request several tests to rule out other, more serious conditions, like septic arthritis. These tests may include:

• Blood tests, like complete blood count (CBC)
• Imaging tests, like X-ray, ultrasound and MRI
• Joint aspiration

How do you treat toxic synovitis?

Treatment for transient synovitis involves supportive care at home. Along with ensuring your child rests their hip, you can:

• Give them nonsteroidal anti-inflammatory drugs (NSAIDs), like ibuprofen (Advil®)
• Apply a warm compress to their hip joint
• Massage their hip

Your child may also find relief by practicing yoga. There are many yoga poses that stretch the hip muscles.

When should my child see their healthcare provider?

If your child develops a fever, their healthcare provider will want to see them right away. A fever may mean your child has a more serious hip condition.

If your child is still experiencing a lot of pain after 10 days, they should see their provider again. Their provider may want to do other tests to make sure your child doesn’t have another condition.

To follow up, your child’s provider may want to see your child again after a week or two. Depending on your child’s situation, they may want to take X-rays of your child’s hip again in 6 months.

How long can toxic synovitis last?

Transient synovitis doesn’t last long. With rest and at-home care, your child’s symptoms should start to improve within 24 to 48 hours. Complete relief from hip pain may take one to two weeks. It may be longer if your child gets back into their normal routine too soon.