Baker Cyst
(Popliteal Cyst)

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Baker cyst facts

  • A Baker cyst is swelling caused by fluid from the knee joint protruding to the back of the knee.
  • Baker cysts are common and can be caused by virtually any cause of joint swelling (arthritis).
  • A Baker cyst may not cause symptoms or be associated with knee pain and/or tightness behind the knee, especially when the knee is extended or fully flexed.
  • Baker cysts can rupture and become complicated by spread of fluid down the leg between the muscles of the calf (dissection).
  • Baker cysts can be treated with medications, joint aspiration and cortisone injection, and surgical operation, usually arthroscopic surgery.

What is a Baker cyst?

A Baker cyst is swelling caused by fluid from the knee joint protruding to the back of the knee. The back of the knee is also referred to as the popliteal area of the knee. A Baker cyst is sometimes referred to as a popliteal cyst. When an excess of knee joint fluid is compressed by the body weight between the bones of the knee joint, it can become trapped and separate from the joint to form the fluid-filled sac of a Baker cyst. The name of the cyst is in memory of the physician who originally described the condition, the British surgeon William Morrant Baker (1839-1896).

What causes a Baker cyst?

Baker cysts are not uncommon and can be caused by virtually any cause of joint swelling (arthritis). The excess joint fluid (synovial fluid) bulges to the back of the knee to form the Baker cyst. The most common type of arthritis associated with Baker cysts is osteoarthritis, also called degenerative arthritis. Baker cysts can occur in children with juvenile arthritis of the knee. Baker cysts also can result from cartilage tears (such as a torn meniscus), rheumatoid arthritis, and other knee problems.

Medically Reviewed by a Doctor on 9/24/2013

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Cyst Symptoms and Causes

A cyst is a closed sac- or bladder-like structure that is not a normal part of the tissue where it is found. Cysts are common and can occur anywhere in the body in persons of any age. Cysts usually contain a gaseous, liquid, or semisolid substance.

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