Transient synovitis


What is transitory synovitis?

Transitory synovitis is a reaction of the inner lining of the joint (synovium) to stimuli, causing thickening of the synovial membrane and/or an excess of joint fluid. The synovium typically reacts to a viral antigen that has entered the bloodstream due to a previous viral infection of the respiratory or digestive system. The affected joint becomes painful, and movement is restricted. Due to the joint’s reaction to external factors, transient synovitis is also referred to as reactive arthritis. The onset of symptoms is usually sudden, often described as happening “overnight.” For example, if the hip is affected by transient synovitis, a child may wake up in the morning unable to walk or limping, causing concern for parents. However, transient synovitis is more like a symptom of previous viral infections, and children generally remain in good overall health, with symptoms resolving within a week.

What is transitory synovitis of the hip?

Transitory synovitis most commonly occurs in the hip and is the most frequent hip disorder in children. It typically affects children around six years of age. In a quarter of cases, it may involve both hips simultaneously. Symptoms in the hip are linked to a previous viral infection, synovial reaction, joint fluid accumulation, and pain. Parents often describe their child limping or being unable to walk after waking up in the morning. Despite attempting to recall traumatic events or intense play from the previous day, such circumstances are not the cause of transient synovitis.

How to diagnose transient hip synovitis?

To confirm transient synovitis of the hip, a lot can be gleaned from conversations with the child, parents, or caregivers. The following steps are necessary:

  • Investigate the presence of elevated body temperature or a possible hip injury.
  • Conduct an examination of the range of motion in the hips or determine any pain during movement.
  • Evaluate the overall condition and gait of the child.
  • Perform an ultrasound examination of the hips and look for joint effusion.

If the child limps and has joint effusion in the hip, basic laboratory tests are needed to rule out bacterial hip infection, such as septic arthritis, which is a critical and dangerous condition. In septic arthritis, children appear unwell, have a fever, cannot walk, and show elevated CRP and ESR values. Meanwhile, children with transient synovitis are generally in good health and may have slightly elevated CRP values. Other conditions that may cause similar symptoms include mesenteric lymphadenitis, juvenile idiopathic arthritis, leukemia, inflammatory bowel diseases, and Legg-Calve-Perthes disease. However, suspicion of these diagnoses arises if there is no improvement within a week, prompting additional tests (X-rays, MRI, bone scintigraphy, or broader laboratory testing).

How to treat transient hip synovitis?

The treatment for transient synovitis of the hip involves activity restriction and pain relief syrup. Young children naturally avoid weight-bearing activities if they are in pain. Restriction from play and jumping for a few days, along with adequate pain relief, usually resolves symptoms within a week. During this time, it is advisable to monitor body temperature. If the child continues to have a fever and/or experiences walking difficulties or pain after a week, a follow-up examination with a pediatric orthopedic surgeon is recommended.

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