Toxic synovitis

Definition

Toxic synovitis is a condition affecting children that causes hip pain and limping.

Alternative Names

Synovitis - toxic; Transient synovitis

Causes, incidence, and risk factors

Toxic synovitis occurs in children before puberty begins. It is a type of arthritis of the hip. Its cause in not known, but boys are affected more often than girls (approximately 4 to 1).

Symptoms

Symptoms may include:

• Hip pain (on one side only)
• Limp
• Thigh pain, in front and toward the middle of the thigh
• Knee pain
• Low-grade fever, less than 101° Fahrenheit

Aside from the hip discomfort, the child does not usually appear ill.

Signs and tests

Toxic synovitis is diagnosed when other, more serious conditions have been ruled out, such as:

• Septic hip
• Slipped capital femoral epiphysis
• Legg-Calve-Perthes disease

Tests used to diagnose toxic synovitis include:

• Ultrasound of the hip
• X-ray of the hip
• ESR
• C-reactive protein (CRP)
• Complete blood count (CBC)

Other tests that may be done to rule out other causes of hip pain:

• Aspiration of fluid from the hip joint
• Bone scan
• MRI

Treatment

Treatment often includes limiting activity to make the child more comfortable. However, there is no danger with performing normal activities. The health care provider may prescribe nonsteroidal anti-inflammatory medications (NSAIDS) to reduce pain.

Expectations (prognosis)

The hip pain goes away within 7 - 10 days.

Complications

Toxic synovitis goes away on its own. There are no expected long-term complications.

Calling your health care provider

Call for an appointment with your child's health care provider if:

• Your child has unexplained hip pain or a limp, with or without a fever
• Your child has been diagnosed with toxic synovitis and the hip pain lasts for longer than 10 days, the pain gets worse, or a high fever develops

References

Hosalkar HS, Horn D, Friedman JE, Dormans JP. The Hip. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 677.