Transient synovitis of the hip: Ultrasound appearance. Mini-pictorial essay.

We describe the ultrasound (US) appearance of transient synovitis. Transient synovitis of the hip typically occurs in 3 to 8-year-old children. The onset is clinically characterized by acute hip pain and limp with limited joint mobility, and the leg is usually held in a position of flexion and external rotation to avoid pain. US image is characterized by joint effusion in the hip joint anterior recess, as described in the literature. Our experience confirms the importance of the technique with which the US examination is performed. In order to obtain the best diagnostic information the hip must be examined with the patient in the supine position and the hip joint in a neutral position (abduction of the hip with extension and slight external rotation) by means of an anterior approach along the long axis of the femoral neck in the parasagittal plane.