Pediatric Transient Synovitis of Hip

  • Etiology: Idiopathic inflammatory process associated with antecedent viral illness leading to fluid in hip joint
  • Imaging Radiograph:
    — Not sensitive or specific for hip effusion but helpful in excluding other pathologies of hip pain
    — See widened hip joint space and bulging joint capsule and thickening of ilioischial line
  • Imaging US:
    — Sensitive to detection of hip effusion
    — If diagnosis is in question compare to contralateral side
  • Imaging MRI: Decreased perfusion of femoral head which is best appreciated with comparison with the contralateral hip
  • DDX: Septic hip is indistinguishable from transient synovitis on US
  • Complications:
  • Treatment:
  • Clinical:
    — Most common cause of hip effusion in children
    — Most common cause of limp and acute hip pain in children less than 10 years old

Radiology Cases of Transient Synovitis of Hip

Radiograph of transient synovitis of the hip
AP (above) and frog leg (below) radiographs of the pelvis show the left femoral head on both views is slightly more displaced laterally than the right femoral head, suggesting the presence of a left hip effusion.
US of transient synovitis of the hip
Sagittal US of the hips shows a large anechoic fluid collection in the anterior recess of the right femur, which is not present in the left hip. This right hip effusion, when tapped under ultrasound guidance, returned clear fluid.
Ultrasound of transient synovitis of the hip
Sagittal US of the hips shows a large anechoic fluid collection in the anterior recess of the left femur, which is not present in the right hip. This left hip effusion, when tapped under ultrasound guidance, returned clear fluid.