The synovium is a layer of connective tissue that lines the surface of synovial joints for the purpose of producing synovial fluid, which acts as a lubricant within the joints, limiting friction. Almost all of the body’s joints are synovial. Transient (temporary) synovitis (inflammation of the synovium) typically presents in children under the age of 10 as a sudden or gradual onset of pain in the inguinal (groin) area. This causes pain with weight bearing and the child may tend to hold their leg in a position of external (outward) rotation, abduction (away from the midline of the body) and flexion (forwards).
The cause of transient synovitis is unknown however it is associated with a history of a prior viral infection, rheumatoid arthritis or Perthe’s disease.