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By Mayo Clinic staffA Baker's cyst is a condition in which you experience a bulge and a feeling of tightness behind your knee. The pain gets worse when you fully extend your knee or when you're active.
A Baker's cyst, also called a popliteal cyst, is usually the result of a problem with your knee joint, such as arthritis or a cartilage tear. Both conditions can cause your knee to produce too much fluid, which can lead to a Baker's cyst. Up to one in five people with other knee problems may develop a Baker's cyst.
Although a Baker's cyst may cause swelling and make you uncomfortable, treating the probable underlying problem usually provides relief.
Symptoms