CuraScript SD - What is a Baker’s Cyst?

What is a Baker’s Cyst?

Posted Wednesday, February 4, 2026

Did you know? Surgery to remove a Baker’s cyst is very rare but may be recommended if it’s caused by a severe knee injury like a ligament tear or broken bone.

Anyone can develop a Baker’s cyst, but they are most common in adults aged 35 to 70, athletes, and people with arthritis.

01 | Introduction

A Baker’s cyst, also known as a popliteal cyst, is a fluid-filled lump behind the knee. These cysts are benign growths that form when something damages the knee joint or the tissues around it. A Baker’s cyst can sometimes cause pain and worsen with activity or when fully straightening or bending the knee. Although it may cause swelling or discomfort, treating the underlying problem of a Baker’s cyst usually provides relief.

02 | Causes

Anything that damages the knee joint can cause swelling and lead to a Baker’s cyst. The most common causes are knee arthritis and injuries, such as cartilage tears. Both of these conditions cause the body to produce excess synovial fluid, the lubricating fluid that reduces friction between the moving parts of the knee. As the pressure builds up, the fluid is pushed to the back of the knee, forming the sac that becomes a Baker’s cyst.

03 | Symptoms

A Baker’s cyst does not always cause pain, and in many cases, the lump that forms behind the knee is the only symptom. Additional symptoms may include:

Knee or leg pain
Tightness, stiffness, or aching in the knee
Difficulty bending the knee
Clicking in the knee
A sense of swelling or fullness behind the knee, especially when straightening the leg
Swelling in the knee, thigh, or calf

These symptoms may worsen after prolonged periods of activity or standing.

04 | Treatments

A Baker’s cyst will not always need treatment. Most cysts will go away on their own when the underlying condition is healed. If symptoms persist, treatment options may involve: