Bakers cyst in knees

by Nathan Wei, MD, FACP, FACR

Nathan Wei is a board-certified rheumatologist and author of the Second Opinion Arthritis Treatment Kit. It's available exclusively at this website... not available in stores.

Click here: Second Opinion Arthritis Treatment Kit




A Baker's cyst is a cystic swelling occurring in the back of the knee. Baker’s cysts may be asymptomatic early on. With further distention, more awareness and discomfort may be noted. This occurs with bending and straightening of the knee.
The cyst is best seen when the patient is standing and is examined from behind. Any disease that affects the knee can lead to a Baker’s cyst.

A naturally occurring communication exists between the knee joint and the semimembranous bursa which is located next to the gastrocnemius muscle.

A one-way valve mechanism exists between the knee joint and the bursa so that fluid from the knee joint can enter the bursa but cannot go back.

Baker’s cysts are common in rheumatoid arthritis, osteoarthritis, mechanical derangements of the knee, reactive arthritis, gout, and psoriatic arthritis. When the cyst pushes back it may cause pressure on the veins leading to edema of the leg that mimics thrombophlebitis (blood clot).

A venogram will exclude the presence of a blood clot. An ultrasound or magnetic resonance imaging scan will help determine the presence of a Baker’s cyst.

A history of a knee effusion (fluid in the knee) generally points towards a Baker’s cyst as opposed to a blood clot. However, the blood clot should be excluded first before presuming that a Baker’s cyst is present.

Treatment of the cyst involves withdrawing fluid from the knee and injecting a glucocorticoid into the knee. This should be done using ultrasound guidance.

Supplementation with leg elevation and ice is also beneficial. For patients who don’t respond to the above, sometimes surgery is needed to remove the cyst.

Return to arthritis home page.