Pediatric Knee Joint Effusion

  • Etiology: Increased amount of fluid in suprapatellar recess
  • Imaging Radiograph:
    — Round homogenous soft tissue density in suprapatellar recess that separates periarticular fat pads greater than 10 millimeters
    — Obliterates posterior border of quadriceps tendon
    — Displaces quadriceps tendon and patella anteriorly
  • DDX:
  • Complications:
  • Treatment:
  • Clinical:

Radiology Cases of Knee Joint Effusion

Radiograph of knee joint effusion
Lateral radiograph of the knee shows a large amount of fluid in the suprapatellar recess that separates the periarticular fat pads >10 mm, obliterates the posterior border of the quadriceps tendon, and displaces the quadriceps tendon and patella anteriorly.

Radiology Cases of Knee Joint Effusion Due to Lyme Arthritis

Radiograph of lyme arthritis of the knees
AP and lateral radiographs of the right knee (above) and left knee (below) shows large bilateral suprapatellar joint effusions, right greater than left.

Radiology Cases of Knee Joint Effusion Due To Tibial Tuberosity Avulsion Fracture

Radiograph and CT of tibial tuberosity avulsion fracture
AP radiograph of the knee (left) shows a double density projecting over the lateral aspect of the proximal tibia. Lateral radiograph of the knee (middle) shows a moderate suprapatellar joint effusion and elevation of the tibial tubercle away from the tibia. Sagittal CT without contrast of the knee (right) shows a fracture line involving the tibial tubercle and extending superiorly into the tibial epiphysis.