A Baker’s cyst, also called a popliteal cyst, is a fluid-filled swelling that forms behind the knee. It often develops as a result of another knee condition like arthritis, a meniscus tear, or joint inflammation.
Some people don’t notice it at all. Others experience a tight, swollen feeling, discomfort when bending the knee, or a visible lump behind the leg. If left untreated, it can limit mobility or even rupture, causing sharp calf pain and swelling.
Baker’s cysts usually result from inflammation or injury inside the knee joint. When the body produces more joint fluid than usual, it may flow into the back of the knee, creating a cyst. Common causes include:
While some Baker’s cysts are painless, others can cause:
Diagnosis involves a physical exam and imaging studies like ultrasound or MRI. These help confirm the presence of a cyst and assess related conditions like arthritis, meniscus tears, or ligament damage. It’s also important to rule out more serious issues like deep vein thrombosis (DVT).
Treatment focuses on relieving symptoms and addressing the root cause of fluid buildup. This may include:
If you experience persistent swelling, pain behind the knee, or calf tenderness, it’s time to get evaluated. Early treatment helps manage symptoms, avoid complications, and protect your long-term joint health.