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.
This order is my second one…. I developed a Baker’s cyst (I think) behind my left knee, jumping up and down hard on a truckload of brush I was trying to compact…. I’m 67 years old, and the next morning, I had pain behind my knees, then a large egg behind my left knee. I searched the internet, and found your website, and ordered the patches. They worked well to bring down the swelling. Then, I jumped up and down on a shovel, digging a ditch, and the swelling returned. I used up the rest of my patches, and the swelling went down.
Thanks very much for having this natural solution to my problem: an egg behind my knee!
★★★★★
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!!
★★★★★
Baker's cyst
Hi Toky,
Received the patches yesterday.
Thanks to you from the old lady for whom I keep purchasing these patches from you. She says these patches are really working wonders on her leg.
Best regards
★★★★☆
Baker's cyst
Dear Toky,
Thank you for the OSMO patches.
I’m seeing a big reduction in the swelling and pain.
Thanks
★★★★★
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.
★★★★★
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,
The Osmo patch definitely helps my baker’s cyst (behind my left knee)!
It is temporary, but the relief is enormous!
I use it every few weeks and the swelling and discomfort abate greatly!
Thank you
★★★★★
Baker's cyst
Hi Toky,
I am amazed at how fast this patch worked! I felt relief the very next morning, all the stiffness having gone and I was able to walk up and down the stairs much more easily.
Thank you so much for all your cooperation in sending a second package. Since I have so many patches now, I am going to spread the word around for you by photocopying the instructions and giving the patch to people with bursitis. My physiotherapist and massage therapist will be one of them.
Real accounts by real people. Hear what they have to say!
★★★★☆
Hello.
The patches arrived. Thank you very much.
I have used 3 and they are very good. They certainly draw the liquid away from the back of my knee.
Thanks very much
★★★★★
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.
★★★★☆
Hello Danniel,
Thank you for your prompt reply.
I started using the patches about 10 days ago, and the amount of improvement is unbelievable. The lump was rock hard, and I could not bend the knee, nor straighten the leg. Even though there is still some swelling, the knee feels almost normal. I have run out of the patches, so will restart as soon as I receive the new batch…hopefully it will all go away.
Thank you for your help, and good luck..
★★★★★
Hi Toky,
Received the patches yesterday.
Thanks to you from the old lady for whom I keep purchasing these patches from you. She says these patches are really working wonders on her leg.