Toxic Synovitis

Toxic synovitis is a childhood condition involving short-lived arthritis of the hip. It occurs before puberty and usually resolves on its own. Boys are affected more frequently than girls. Most children affected are between ages 3 and 10. Other than direct injury, toxic synovitis is the most common condition that can cause hip pain and limping in children.

CAUSES

The exact cause of toxic synovitis is unknown. Some research has indicated a possible relationship to infection with a virus. About half of the children with toxic synovitis have had an upper respiratory infection shortly before developing hip symptoms. Other research suggests that injury to the painful area might trigger the problem.

SYMPTOMS

Symptoms are usually mild. Aside from hip discomfort and limping, the child does not usually appear ill. Symptoms may include:

  • Hip pain (on one side only).

  • Limping.

  • Thigh pain, in front and toward the middle.

  • Knee pain.

  • Low grade fever, less than 101° F (38.3° C).

DIAGNOSIS

Toxic synovitis is diagnosed when other, more serious conditions, have been ruled out. In children, there are several potentially serious diseases that can cause hip pain and limping, including:

  • Septic or bacterial infection in the hip joint or bones of the hip.

  • Slipped capital femoral epiphysis. This means the hip bone slips out of place.

  • Legg-Calve-Perthes disease. This is a condition that results from a decrease in blood flow to the hip. This condition may run in the family or it may be due to another condition like kidney failure.

  • Systemic arthritis, such as psoriatic arthritis.

  • A common noncancerous tumor of the bone called osteorid osteoma and less commonly a bone cancer.

The following tests may be done:

  • Physical exam.

  • Blood tests.

  • Urinalysis and culture.

  • X-rays.

  • Ultrasound. Your doctor may do this to look for fluid in the hip joint if your child has symptoms of infection. If fluid is seen, the ultrasound may be used to help guide the caregiver in carrying out a procedure called needle aspiration. This procedure is done to remove a small amount of fluid from the joint to be examined in the lab.

  • Magnetic resonance imaging (MRI).

TREATMENT

  • Massage may be helpful.

  • Over-the-counter medicines may be helpful for controlling pain.

HOME CARE INSTRUCTIONS

  • Only give over-the-counter medicines for pain, discomfort, or fever as directed by your caregiver.

  • Keep your child comfortable. Bed rest may be needed for up to 7 to 10 days.

  • Make sure your child avoids putting weight on the affected leg.

  • Make sure your child avoids full activity until the limp and pain have gone away almost completely.

  • Keep all follow-up appointments as directed. Your child may need repeat X-rays of the affected hip 6 months after the problem first develops.

SEEK MEDICAL CARE IF:

  • Your child's hip pain or limping lasts for more than 7 to 10 days after the problem first starts.

  • Your child's pain is not controlled with medicines.

  • Your child's pain gets gradually worse rather than better.

  • Your child develops pain in other joints.

  • Your child develops redness over the joint.

SEEK IMMEDIATE MEDICAL CARE IF:

  • Your child develops severe pain.

  • Your child develops a fever over 102° F (38.9° C).

  • Your child cannot walk.