The knee is filled with synovial fluid, which reduces friction between the bones of the knee joint while you move. Sometimes this fluid accumulates in the back of your knee. A Baker’s cyst or popliteal cyst is a fluid-filled swelling that develops behind the knee. This causes stiffness, tightness and pain behind your knee. It is commonly seen in women and people aged over 40 (although it can develop at any age).
A Baker’s cyst may not cause any pain and may go unnoticed. You may, however, experience symptoms such as swelling behind your knee and leg, stiffness, and pain behind the knee towards the upper calf (especially when you bend your knee or straighten it completely). Pain can become severe when you flex your knee and when you are active. Sometimes the cyst can rupture and the fluid can drain into the tissues of the lower leg, causing swelling and redness.
Baker’s cyst is caused by underlying conditions such as meniscal tears, capsular tear, rheumatoid arthritis, or osteoarthritis.
In addition to physical examination, Dr. Fischer may order imaging such as ultrasound scan ir MRI to confirm the diagnosis of Baker’s cyst.
Most often a Baker’s cyst does not require treatment and will improve on its own. If the cyst is large and causes persistent pain, the following treatments may be recommended:
- Medications: Dr. Fischer injects corticosteroid into your knee to reduce pain and swelling. The cyst may recur over time if the inflammation and joint swelling return.
- Fluid drainage: Fluid from the cyst can be drained using a needle that is guided by ultrasound. Steroid injections sometimes follow fluid drainage to reduce inflammation and pain.
- Physical therapy: Dr. Fischer may suggest the application of ice and a compression wrap or crutches to help reduce the pain and swelling. He/she may also include strengthening and range-of-motion exercises for the muscles around the knee.
- Surgery: Dr. Fischer may treat the underlying cause rather than the condition itself. If a cartilage tear is causing the over production of synovial fluid, surgery may be required to repair or remove the cartilage.