Knee Effusion
Look For
- Fluid in the suprapatellar pouch
- Fluid in Hoffa's triangle (anteriorly, between the femur and tibia)
- Separation of the anterior fat pads of the knee
Causes of Knee Effusion
- Trauma - ligament tear, menisceal tear, intra-articular fracture, patellar dislocation
- Arthritis - osteoarthritis, psoriatic arthritis, reactive arthritis, IBD-related arthritis, gout, pseudogout
- Infection - septic arthritis, tuberculosis, Lyme disease, syphilis
- Malignancy - osteosarcoma
Teardrop Sign (Ankle)
Look For
- A teardrop-shaped hyperdensity anterior to the ankle joint, due to displacement of the pretalar fat pad by fluid within the joint space.
Significance
- Ankle joint effusion, suggestive of an occult fracture.
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