To evaluate the significance of arthrocentesis on transient synovitis of hip in children with a moderate degree of limping and large joint effusion.

119 cases of transient synovitis of the hip were evaluated retrospectively between January 1999 and December 2003, with respect to age (mean age: 5.6 years), sex (M: F=89: 30), location (Right: Left=68: 51), chief complaints (limping: 72; hip pain: 39; knee pain: 37), physical examination (limited internal rotation: 98), sonography of capsule neck distance (mean 5.9 mm), duration of hospitalization and morbidity. Among them, 47 cases with greater than 8 mm in capsule neck distance on sonography were compared, based on the duration of hospitalization, morbidity, and the change of capsule bulging between 18 cases in the arthrocentesis group and 29 cases in the non-arthrocentesis group.

The mean duration of hospitalization and morbidity were 1.7 days, 4.7 days in the arthrocentesis group and 2.1 days, 6.6 days in the non-arthrocentesis group, the distance of the capsule bulging decreased from 9.2 mm to 4.5 mm in the arthrocentesis group and from 9.0 mm to 7.6 mm in the non-arthrocentesis group. The duration of hospitalization, morbidity, clinical course and decrease in capsule bulging were more effective, statistically in the arthrocentesis group than in the non-arthrocentesis group.

Arthrocentesis for transient synovitis can be effective method of treatment in cases of moderate degrees of limping and large joint effusions, in spite of the disadvantage of the invasiveness of the procedure.