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.
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 braces, crutches and hydrotherapy plus physiotherapy, it seemed I had gained a cyst at the back of my knee. This tight swelling really hindered my ability to improve and I looked to the internet for answers-where I found your advert
Although I had never heard of your product and neither had my physiotherapist, I decided to give them a try as they wouldn’t hurt even if they didn’t help. The day I woke up after the first patch I was really surprised. I didn’t say anything to my husband because I didn’t want to jinx the feeling I had! The tightness had lessened dramatically which meant I could walk as soon as I got up, not the usual stretch and wait for it to get going!! My physio noticed a difference the next visit as it was the first time I could get my leg flat and flex my foot slightly. The reduction in swelling and tightness was brilliant. Although I have only used two my leg has improved so much and it helps that I can exercise properly to strengthen my muscles.
Thanks for your help I am no longer sceptical about the patches-will be ordering more in the future!
★★★★★
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.
★★★★★
Baker's cyst
Dear Folks in Australia,
I have just placed my third order with you for your OSMO Patches because they do work and I am so impressed with how they work. No one here at my end has ever seen anything like your patches and I love telling people about them.
I suffer from a Baker’s Cyst and so far, this is the only thing that alleviates the swelling. As you say in your literature, it doesn’t really cure the Cyst but it does give it relief. Amazing!!!
Best wishes
★★★★★
Baker's cyst
Thank you.
I never thought I would be able to walk without pain again.
Thanks to your product, I was pain free the day after I applied the first patch.
★★★★★
Baker's cyst
Thank you for responding.
I think I will save my last two patches in case I need them. Right now, I have such great improvement, I am no longer wearing the knee brace and I can walk up and down stairs with alternating feet.
Have not done that for a while!
Thanks again,
★★★★☆
Baker's cyst
Hi Toky,
Thank you very much for sending the patches to Ukraine.
My mother finds them very helpful and asked if I could get her more.
Regards
★★★★★
Baker's cyst
Thank you for your excellent product.
First use was fantastic and after five times it had solved my problem of my swollen and stiff knee. I ordered another batch just to keep some extras on hand because from now on, I won’t do without them.
I have already recommended them to several people that have had similar problems. Thanks again for your wonderful product. I’m very grateful for the OSMO Patches.
★★★★★
Baker's cyst
Hello!
I am writing to sing your praises! I am not kidding. I was first diagnosed with a Baker’s cyst approximately three months ago. The pain became increasingly intense, so I finally made an appointment with an orthopedic surgeon. He explained that the cyst was most likely the result from a torn meniscus and that I would require surgery. In the meantime, my patches I had ordered arrived, so I had used five patches by the time I returned to the orthopedic surgeon for the follow up for my MTI. He did NOT find a torn meniscus and was amazed at how much more range of motion I had in my knee. He agreed “whatever is working, keep it up!”
I am 62 years old, quite active, practice yoga and exercise daily. I am currently planning to swim with the dolphins with my grandchildren next month instead of planning surgery, physical therapy, etc. THANK YOU!!
Real accounts by real people. Hear what they have to say!
★★★★☆
Dear Sir or Madam:
I purchased the OSMO patch several weeks ago and just started using them 4 days ago for my Bakers Cyst behind my knee.
I must admit I was very skeptical but I have noticed a change and less swelling in the area behind my knee.
Thank you
★★★★★
To whom it may concern,
Got my patches yesterday and skeptically put one on last night.
I woke up this morning astonished, pain gone, flexibility back.
Don’t know how you discovered this but thank you. I will be ordering more as needed.
★★★★★
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.
★★★★☆
I received the patches. Thank-you.
I am happy with the results and will use this product in the future.