What are Baker's Cysts? Causes & Symptoms Explained!
Last reviewed on 25 October 2025 by
Danniel Jacques
(B.Med.Sci UNSW)
What is a Baker’s Cyst?
A baker cyst is a painful condition which can be characterised by swelling in the back of the knee.
This swelling occurs due to inflammation in the synovial joint which encapsulates the knee resulting in the out-pouching of fluid into a little balloon type sac from the synovial lining.
When this condition develops, synovial fluid (which is normally contained in a tough capsule that encases the knee joint) collects in the baker’s cyst and bulges behind the knee.
This is also called a “popliteal cyst” as it directly affects the popliteal region of the knee (that shallow depression located behind the knee joints).
If left untreated it is possible for it to rupture. A ruptured baker’s cyst may then cause the collected synovial fluid to transfer and travel down the calf muscles of the legs. This can then trigger rapid swelling and discomfort of the leg which may then cause further complications.
What Causes a Baker’s Cyst?
Baker’s cysts are quite common and can be caused by nearly any joint-related inflammation. Some of the most common causes may include;
A micro tear in the knee’s meniscal cartilage
Repetitive stress injury.
Wear & tear in the knee (which is more common in older adults)
Injury to the anterior cruciate ligament of the knee (ACL injury)
Sports-related injury that affects the knee
The type of work that a person does may also make them more susceptible. This include jobs that involve being on your knees, such as a gardener or carpenter. Also such jobs that require long shifts without sitting or unusual weight loading through the knees such as nursing.
Symptoms may include visible swelling or protrusion on the back of the knee (which can be either with our without pain), constant and prolonged knee pain, and tightness at the back of the knee or simply a feeling of tenderness at the back of the knee.
If left untreated a baker’s cyst may actually rupture. A ruptured or burst baker’s cyst can cause a lot of pain and discomfort and can present very similarly as a blood clot as there will also often be calf related pain.
How to diagnose a baker’s cyst?
It is always best to visit a qualified medical professional if you suspect that you have either a baker’s cyst or feel that your baker’s cyst may have ruptured or burst.
Your doctor will likely require you to have an ultrasound which will be able to confirm a diagnosis of baker’s cyst and also importantly rule out or alert the doctor of any existence of a blood clot.
If there is an infection suspected then a blood test and maybe an aspiration of the synovial fluid may be required for testing and culturing. In some cases an x-ray and or MRI may also be required to rule out any co-exist conditions that may have contributed to the condition.
Real accounts by real people. Hear what they have to say!
Baker's cyst
Hello Toky,
I used the patches for 5 nights on by left knee with bakers cyst and by the fifth time, the patch was dry- I then took that to mean that all fluid has been removed.
It’s been 2 days since that I have no pain, no more swelling at back of left knee, compared to my right knee they both feel/look the same size, which tells me they are normal sizes again.
Thank you very much for making this fabulous miracle patch available… Staying Positive with a huge SMILE!
Vannette H
Ontario, Canada
Baker's cyst
Hello,
I recently ordered the OSMO Patches and have already felt the pain decrease on my baker’s cyst.
Thank you.
Patricia N
Arizona, United States
Knee Baker's Cysts and Meniscus tears
I’ve had knee problems for 3 decades and have had 4 surgeries due to an ACL tear and numerous Meniscus tears. Due to these problems, I’ve had a chronic problem with a Baker’s Cyst which I’ve been living with for years and the swelling has kept me in constant pain.
I definitely recommend the OSMO patches. They have given me substantial relief from the pain that I was experiencing. I’ve recommended the patches my Physical Therapist and he’s recommended them to his patients. I’ve also recommended the patches to my Surgeon and he is now recommending the patches in lieu of injections.
William M
California, United States
Baker's cyst
Dear Toky,
Thank you for the OSMO patches.
I’m seeing a big reduction in the swelling and pain.
Thanks
Margery D
New York, United States
Baker's cyst
Hi there!
My mother had 20 patches, it made a lot of difference for her knee, she got a big relief out of it, she started bending her knee now after many years,
With best regards
Mesrak M
Argyll, United Kingdom
Baker's Cyst
Thank you for your information. We have experienced a great effect on my mother’s Baker cyst.
Neval A
VIC, Australia
Baker's cyst
Hi Just a quick note that I feel I needed to write about the OSMO Patches. In September I tripped over while running and fell on my knee which left me with a fractured bone at the back of my knee which in turn ruptured my cruciate ligament. Although back on track now after various […]
Kim C
South Yorkshire, United Kingdom
Baker's cyst on both knees
I have been meaning to write you for some time now and tell you how great the OSMO patches have worked for me.
I have had Baker’s cysts over the past 4 years on both knees. My Orthopedic Specialist drained them numerous times, plus gave me cortisone shots. Researching the topic one day, I discovered your website and hesitantly ordered the patches… they work amazingly. There is such a difference when I wake up in the morning.
The fluid is drawn out and mobility is greatly improved. I will probably need surgery one day to repair torn cartilage in my knees, but these are greatly helping me with the swelling/fluid buildup like nothing else has before.
Thank you for developing such a wonderful product and for the prompt and efficient service. They are really helping me.
