Overview
A swollen knee occurs when excess fluid collects in or around your knee joint. Health care providers might refer to this condition as an effusion (uh-FU-zhun) in your knee joint.
A swollen knee may be the result of trauma, overuse injuries, or an underlying disease or condition. To find the cause of the swelling, your provider might need to test a sample of the fluid for infection, disease or blood from an injury.
Removing some of the fluid may help reduce the pain and stiffness associated with the swelling. Once the underlying cause is known, treatment can begin.
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