How about children's hip synovitis?

Synovitis is an abnormal and morphological change of synovial tissue in joints caused by many reasons, which leads to excessive synovial fluid production and absorption disorders, and produces diseases with recurrent joint swelling and pain and muscle atrophy as the main clinical manifestations. Hip synovitis is also called transient synovitis of hip joint. Children under 3- 10 are prone to hip synovitis, especially males. Most children have sudden onset. The incidence peak is 3-6 years old, and the right side is more than the left side, accounting for 5% of bilateral hip joints. The cause of the disease may be related to virus infection, trauma, bacterial infection and allergic reaction. The onset can be urgent or slow. The child complained of pain in the front or side of thigh and knee joint, and physical examination could find pain-avoiding gait, anterior tenderness of hip joint, limited range of motion and discomfort.