A Baker's cyst is a bulge in the back of the knee filled with synovial fluid. It often develops as a result of a condition or injury to the knee joint, such as osteoarthritis, meniscal damage, or inflammatory changes. While small Baker's cysts often cause no symptoms, larger cysts can lead to pain, a pronounced feeling of tightness, and limited range of motion.
At the ROC in Aschheim near Munich, we therefore examine not only the Baker’s cyst itself, but also—and in particular—the underlying cause in the knee. In addition to conservative treatments, we offer catheter-guided bipolar thermal ablation (RFITT) as a minimally invasive treatment option for Baker’s cysts when medically indicated.
A Baker's cyst—also known as a popliteal cyst or synovial cyst—is a bulge filled with synovial fluid in the back of the knee. It develops when excess fluid accumulates in the knee joint and flows into a bursa connected to the joint at the back of the knee.
In adults, therefore, a Baker's cyst is often not the actual disease itself, but rather a consequence of a problem within the knee joint. For effective long-term treatment, it is therefore important to diagnose not only the cyst but also its underlying cause and, if necessary, treat it.
A Baker's cyst often develops when a condition or injury to the knee joint leads to increased production of synovial fluid.
Possible causes include, among others:
The excess synovial fluid can accumulate in a bursa through a connection to the back of the knee. The bursa enlarges, forming the typical cyst.
That is why, at ROC Ortho, a thorough examination of the knee joint is a top priority before treatment begins.
Small Baker's cysts often go unnoticed and are sometimes discovered by chance during an examination of the knee. However, as they grow larger, symptoms may develop.
Typical symptoms include:
In some cases, pain or swelling may radiate down into the calf.
The first step is a thorough orthopedic examination. During this examination, we not only assess the size and location of the Baker’s cyst, but also specifically look for any possible changes within the knee joint.
Depending on the findings, imaging techniques such as ultrasound or MRI may be appropriate. MRI, in particular, provides a detailed view of the menisci, cartilage, ligaments, and other structures of the knee joint.
At the ROC, our open MRI scanner, located directly on the Aschheim campus, is also available for this purpose when the specific clinical question warrants it.
The goal of the diagnostic evaluation is to answer the key question: Why did the Baker's cyst form?
Not every Baker's cyst requires treatment. If it causes no symptoms or only mild symptoms, it can be monitored initially. For symptomatic Baker's cysts, treatment depends on the size, symptoms, and, in particular, the underlying cause.
Depending on the findings, various treatment approaches may be considered.
For milder symptoms, conservative measures can be used initially. These include, for example, temporarily adjusting the level of physical activity, physical therapy, and targeted treatment of the underlying knee condition.
The appropriate treatment depends largely on the cause of the increased fluid buildup in the knee.
During a puncture, fluid is removed from the cyst using a needle. This helps reduce the pressure in the back of the knee initially.
However, the aspiration does not automatically eliminate the cause of the fluid buildup. If the underlying condition affecting the knee joint persists, fluid may accumulate again and the Baker's cyst may recur.
In cases of severe symptoms, surgical treatment may be an option in certain situations. Whether surgery is necessary and appropriate depends on the individual’s situation and the underlying knee condition.
At the ROC, we offer an additional treatment option when medically indicated: catheter-assisted bipolar thermal ablation (RFITT).
In this procedure, the Baker's cyst is not removed through a large open incision. Instead, after local anesthesia, a catheter or electrode is inserted into the cyst using a minimally invasive technique.
High-frequency bipolar alternating current generates controlled heat in the treated tissue. The goal is to apply thermal energy to the cyst wall and cause the tissue to shrink.
The use of catheter therapy for Baker's cysts is considered off-label. Before treatment, we therefore provide a detailed explanation of the procedure, possible alternatives, and the associated benefits and risks.
Treating a Baker's cyst alone is not always sufficient. For example, if osteoarthritis, meniscal damage, or another knee joint condition persists, excess synovial fluid may continue to accumulate.
This means there is always a possibility that a Baker's cyst could form again.
At the ROC, we therefore evaluate the cyst and the knee joint together. Using targeted diagnostic tests, we first determine which changes in the joint may be responsible for the symptoms and the accumulation of fluid.
We then develop a personalized treatment plan that addresses both the Baker's cyst and—if necessary—the underlying knee condition.
Before the procedure, we will perform a thorough examination of the knee joint. During this examination, we will determine whether RFITT treatment is appropriate for your specific condition and whether additional treatment for the underlying knee condition is necessary.
The procedure is minimally invasive and performed under local anesthesia. The electrode is inserted into the Baker's cyst through a small incision. The cyst wall is then subjected to controlled thermal treatment.
After the procedure, you will receive personalized recommendations regarding physical activity and follow-up care. How soon you can put weight on your knee again depends on the specific findings and any underlying conditions affecting the knee joint.
Comprehensive Knee Diagnostics
We don't just examine the Baker's cyst; we specifically investigate its possible cause within the knee joint.
Minimally Invasive Therapy
When indicated, RFITT can be a minimally invasive treatment option.
Modern Imaging
With ultrasound and our open MRI scanner, we offer important diagnostic options right on-site.
Personalized Treatment Plan
Treatment depends on your symptoms, the cause of the Baker's cyst, and the condition of the entire knee joint.
Dr. med. Daniel Filesch
Specialist in orthopaedics and trauma surgery
Martina Berger
Doctor for regenerative orthopaedic procedures
Dr. med. Edan Manos
Doctor for regenerative orthopaedic procedures
Patrick Heine
Specialist in orthopaedics and trauma surgery
Do you have swelling behind the knee, pain, or have you already been diagnosed with a Baker's cyst? At the ROC, we examine both the cyst and possible causes within the knee joint.
Based on the diagnostic findings, we will discuss with you whether conservative therapy, a puncture, the minimally invasive RFITT treatment, or another treatment for the underlying knee condition is appropriate.