A Baker cyst is a buildup of joint fluid behind the knee. It creates a tight bump behind the knee.
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 small fluid-filled sac (bursa) between the bone and soft tissue of the knee.
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Things that may raise the risk of this problem in adults are:
Things that may raise the risk of this problem in children are:
Problems may be:
The doctor will ask about your symptoms and health history. A physical exam will be done. It will focus on the knee.
Images of the knee may be taken. This can be done with:
The problem 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 need to be treated. The goal of treatment is to manage symptoms and promote healing. Options are:
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 this health problem.
Ortho Info— American Academy of Orthopaedic Surgeons
Sports Med—American Orthopaedic Society for Sports Medicine
Canadian Orthopaedic Association
Canadian Orthopaedic Foundation
Frush TJ, Noyes FR. Baker's Cyst: Diagnostic and Surgical Considerations. Sports Health. 2015 Jul;7(4):359-365.
Popliteal cyst. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/popliteal-cyst. Accessed January 29, 2021.
Last reviewed December 2020 by
EBSCO Medical Review Board
Teresa Briedwell, PT, DPT, OCS, CSCS
Last Updated: 1/29/2021