A Baker’s cyst, or popliteal cyst, is a fluid filled sac that occurs behind the knee. Symptoms of a Baker’s cyst include pain, swelling or a lump behind the knee. This area of swelling may cause stiffness as well as a fullness or tightness sensation when bending or straightening the knee. These symptoms often worsen with activity and may improve at rest. Some people may have no symptoms whatsoever.
A Baker’s cyst is filled with synovial fluid, the lubricating fluid of the knee joint. A Baker’s cyst occurs as a result of too much synovial fluid buildup, forcing fluid into the space behind the knee. This may occur for many different reasons such as arthritis, injury to the knee such as a meniscus tear, or even gout.
However rare, Baker’s cyst can rupture leading to pain, swelling, and redness to the lower leg. It is important to have these particular symptoms evaluated as they may mimic other serious conditions such as blood clot.
Diagnosing a Baker’s cyst involves taking a medical history, physical examination, x-rays of the knee, and in some cases ultrasound or magnetic resonance imaging (MRI). Identifying the underlying cause of the Baker’s cyst is key to treatment and management. Treating the cause of the excess synovial fluid, will likely lead to resolution of the cyst. Because of the important anatomical structures behind the knee (popliteal fossa), it is very rare that Baker’s cysts are surgically removed. It’s a common misconception that every Baker’s cyst needs to be drained, injected or excised. Treatment options may include: activity modifications, anti-inflammatory medications, ice therapy, supportive knee brace, physical therapy, steroid joint injections, arthroscopic or joint replacement surgery.
Living with a Baker’s cyst depends on how much discomfort it causes. Often times, the size and presence of the cyst will fluctuate, as the body can resorb this excess fluid. No treatment is necessary if the cyst is not causing discomfort.