DESCRIPTION

• Transient synovitis is classically defined as a self-limited inflammatory process resulting in pain and limited range of motion of the hip, often precipitated by a viral infection, also known as “toxic synovitis.” Transient synovitis falls under the classification of postinfectious or reactive arthritis.
• This chapter focuses on transient synovitis of the hip. Other postinfectious arthritides are defined within the “Differential Diagnosis” section.

EPIDEMIOLOGY

• Most common cause of acute pediatric hip pain
• Most common in ages 3 to 8 years
• Males are affected approximately 2 times more frequently than females.

ETIOLOGY

• Usually postinfectious as case series have shown associated antecedent upper respiratory, gastrointestinal, or urinary tract infections (UTIs)
• Traumatic, allergic, and postvaccination etiologies have been proposed, but there is limited supporting data of relationship.

RISK FACTORS

No specific associations

PATHOPHYSIOLOGY

Unclear