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Toxic Synovitis of the Hip in Children

Medically reviewed by Last updated on Nov 5, 2023.

What is toxic synovitis of the hip?

Toxic synovitis of the hip is swelling of your child's hip joint. The hip joint is where your child's hip bone and leg bone meet. Toxic synovitis of the hip can occur at any age, but is most common in children 3 to 10 years old. It does not spread to other parts of the body. It may also be called transient synovitis of the hip.

Normal Hip Joint

What causes toxic synovitis of the hip?

The cause of toxic synovitis of the hip is unknown. It more commonly occurs after a lung or stomach virus. It may also occur after a trauma.

What are the signs and symptoms of toxic synovitis of the hip?

Your child may have any of the following:

  • Sudden pain in the hip, upper leg, or knee. The pain causes your child to limp when he or she walks.
  • Limited leg and hip motion. Your child may sit or lie with his or her legs apart in an unusual position.
  • A low fever of 100ºF or less.

How is toxic synovitis of the hip diagnosed?

A healthcare provider will examine your child's hip and leg to locate his or her pain. The provider may ask when your child's symptoms began. Your child's leg and hip movement will be checked. Your child may also need the following tests:

  • Blood tests: Your child may need blood drawn for tests. The blood may be taken from your child's arm, hand, finger, foot, or heel. Blood tests may show if an infection has caused your child's symptoms.
  • MRI: During an MRI, pictures are taken of your child's bones, joints, muscles, or blood vessels. Your child will need to lie still during the MRI. Never let your child enter the MRI room with any metal objects. This can cause serious injury.
  • X-ray: This is a picture of your child's hip. A hip x-ray may show signs of infection or other problems.
  • Ultrasound: This is a test that helps healthcare providers see inside your child's body. Sound waves are used to show pictures of his or her hips on a TV-like screen. Healthcare providers may use the ultrasound to help find and remove fluid from the hip joint.
  • Bone scan: During this test, pictures are taken of your child's bones. Your child is given a small, safe amount of radioactive dye in an IV. Healthcare providers can look at the pictures for broken bones, infection, or problems in the bones.

How is toxic synovitis of the hip treated?

Toxic synovitis may go away on its own within 1 to 3 weeks. Rest and limited leg movement may help your child improve more quickly. Your child may also be told to keep weight off his or her leg until pain is reduced. Your child may also need the following:

  • NSAIDs , such as ibuprofen, help decrease swelling, pain, and fever. This medicine is available with or without a doctor's order. NSAIDs can cause stomach bleeding or kidney problems in certain people. If your child takes blood thinner medicine, always ask if NSAIDs are safe for him or her. Always read the medicine label and follow directions. Do not give these medicines to children younger than 6 months without direction from a healthcare provider.
  • Pain medicine: Your child may be given medicine to take away or decrease pain. Do not wait until the pain is severe before you give your child his or her medicine.
  • Acetaminophen: This medicine is available without a doctor's order. It may decrease your child's pain and fever. Ask how much medicine your child needs and how often to give it.
  • Steroids: Rarely, your child may be given steroids to help decrease redness, pain, and swelling.
  • Do not give aspirin to children younger than 18 years. Your child could develop Reye syndrome if he or she has the flu or a fever and takes aspirin. Reye syndrome can cause life-threatening brain and liver damage. Check your child's medicine labels for aspirin or salicylates.
  • Give your child's medicine as directed. Contact your child's healthcare provider if you think the medicine is not working as expected. Tell the provider if your child is allergic to any medicine. Keep a current list of the medicines, vitamins, and herbs your child takes. Include the amounts, and when, how, and why they are taken. Bring the list or the medicines in their containers to follow-up visits. Carry your child's medicine list with you in case of an emergency.

When should I follow up with my child's healthcare provider?

Follow up with your child's healthcare provider within 2 days. Write down your questions so you remember to ask them during your visits.

When should I contact my child's healthcare provider?

  • You think the medicine is not helping your child.
  • Your child's symptoms, such as pain and limping, do not improve within 3 weeks on their own, or within 2 days with medicine.
  • You have questions or concerns about your child's condition or care.

When should I seek immediate help?

Seek care immediately or call 911 if:

  • Your child's symptoms get worse or do not go away.
  • Your child cannot put any weight on his or her leg.
  • Your child's fever is higher than 100ºF.

Care Agreement

You have the right to help plan your child's care. Learn about your child's health condition and how it may be treated. Discuss treatment options with your child's healthcare providers to decide what care you want for your child. The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.

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Further information

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