Transient Synovitis

Updated: Dec 20, 2018
  • Author: Christine C Whitelaw, MD; Chief Editor: Lawrence K Jung, MD  more...
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Transient synovitis (TS) is the most common cause of acute hip pain in children aged 3-10 years. [1] The disease causes arthralgia and arthritis secondary to a transient inflammation of the synovium of the hip.



Biopsy reveals only nonspecific inflammation and hypertrophy of the synovial membrane. Ultrasonography demonstrates an effusion that causes bulging of the anterior joint capsule. Synovial fluid has increased proteoglycans.




United States

Little data are available regarding the frequency of this illness. However, excluding infections and trauma, transient synovitis is one of the most common causes of joint pain in the pediatric age group.


The Netherlands report an incidence of 76.2 per 100,000 person-years.


The possible etiologic relationship between transient synovitis and Legg-Calvé-Perthes disease (LCP) is controversial. [2] Although some children with transient synovitis may develop LCP, whether persistence of increased intraarticular pressure eventually causes avascular necrosis or whether patients may have a synovitis that occurs before detection of femoral head collapse is not fully known. Approximately 1.5% of patients with transient synovitis develop LCP, Coxa magna, osteoarthritis, or recurrences.


Transient synovitis affects boys twice as often as girls.


Transient synovitis most frequently occurs in children aged 4-10 years; [3] however, transient synovitis has been reported in a 3-month-old infant and in adults. Nonetheless, children outside the typical age group are unlikely to have transient synovitis. Some teenagers with enthesitis-associated arthritis are initially diagnosed erroneously with toxic synovitis when they first present with hip pain.