Baker's Cyst



Joint fluid helps the knee move smoothly. A Baker cyst happens when excess fluid is pushed out to the back of the knee.

Sometimes the cause is not known. In adults, it may be due to underlying problems with the knee joint. In children, it may be due to problems with the fluid filled sac (bursa) between the bone and soft tissue of the knee.

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Risk Factors

Things that may raise the risk of a Baker cyst in adults are:

  • Past knee injuries or cartilage tears
  • Osteoarthritis—wear and tear of cartilage between bones
  • Inflammatory diseases, such as rheumatoid arthritis and gout
  • Previous knee surgery

Things that may raise the risk of this problem in children are:

  • Osteochondritis dissecans—death of bone tissue in the knee
  • Meniscus tears —a partial or full tear of the cartilage of the knee
  • Prior knee surgery



Problems may be:

  • Rounded swelling behind the knee that may get bigger with activity
  • Aching or tenderness after exercise and bending the knee
  • Pain or pressure in the back of the knee
  • Pain that may travel to the calf


The doctor will ask about symptoms and past health. A physical exam will be done. It will focus on the knee.

Images of the knee may be taken. This can be done with an:

  • Ultrasound
  • MRI scan
  • CT scan



A Baker cyst may go away on its own without treatment. In others, the underlying cause may need to be treated.

A cyst that is painful or impacting daily life may also need to be treated. The goal of treatment is to manage symptoms and promote healing. Options are:

  • Medicines to ease pain and swelling, such as:
    • Over the counter pain relievers
    • A corticosteroid injection
  • Physical therapy to improve strength, flexibility, and range of motion
  • Draining excess knee fluid with a needle

People who are not helped by these methods may need surgery. It may be done to remove the cyst or repair a damaged knee joint.


There are no current guidelines to prevent a Baker cyst.

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

Edits to original content made by Denver Health.