17/08/2025
A Baker’s cyst, also called a popliteal cyst, is a fluid-filled swelling that develops in the popliteal space the area behind the knee. It forms when excess synovial fluid, which normally lubricates the knee joint, is pushed into a small sac-like pocket behind the knee. This typically occurs when there is increased fluid production within the joint, often due to underlying knee problems such as arthritis, meniscus tears, or inflammation.
The cyst itself can vary in size and may cause different levels of discomfort. Some people may not have any symptoms, while others may experience a noticeable bulge behind the knee, stiffness, or pain that worsens with activity or full flexion and extension of the knee. The swelling may become more obvious when standing and can decrease when the knee is flexed.
Baker’s cysts are not inherently dangerous, but they can cause complications. In some cases, the cyst may rupture, causing fluid to leak into the calf muscles, which can lead to sharp pain, swelling, and redness in the lower leg sometimes mimicking a blood clot. Diagnosis is often made through physical examination, but imaging such as ultrasound or MRI can confirm the presence and underlying cause. Treatment focuses on addressing the primary knee condition, reducing inflammation, and relieving discomfort. This can include rest, compression, anti-inflammatory medications, corticosteroid injections, or in persistent cases, aspiration or surgery. ’sCyst