The effect of arthrocentesis in transient synovitis of the hip in the child: a longitudinal sonographic study.

Twenty-one children with transient synovitis of the hip were treated in two consecutive groups. In 12 patients aspiration of the synovial effusion was performed within 24 h of admission. In a second group of nine patients no aspiration was performed. There was no other difference in treatment. Joint effusion was studied sonographically in comparison with the nonsymptomatic contralateral hip. Sonography was performed immediately after admission, within 12 h after aspiration, and repeatedly during a follow-up period of up to 15 days. Following aspiration the capsular distention decreased to 49% but recurred within 24 h to 72% of the preoperative value. However, during the first 4 days of follow-up the capsular distention in the aspirated cases was significantly and permanently lower than in the nonaspirated cases. We conclude that arthrocentesis in the acute stage of transient synovitis of the hip in the child permanently reduces the intracapsular effusion.