Popliteal cyst - Baker's cyst

A popliteal or Baker's cyst is a build-up of joint fluid which appears at the back of the knee (popliteal fossa). When the pressure builds up, the fluid puts pressure on the back of the knee. A large cyst can cause some discomfort or rigidity, but generally, there are not any symptoms. There may be a feeling as if there was a balloon full of water. Sometimes, the cyst may open (break) and produce pain, inflammation and hematoma in the back of the knee and the calf. The diagnosis is performed through the clinical history and full physical examination without the need for any additional imaging tests. Usually, treatment is not required. If the cyst is painful, the goal of the treatment is to correct the problem which causes it.