Baker Cyst

A Baker cyst, also called a popliteal cyst, is a sac-like growth that forms at the back of the knee. The cyst forms when the fluid-filled sac (bursa) that cushions the knee joint becomes enlarged. The bursa that becomes a Baker cyst is located at the back of the knee joint.

CAUSES
In most cases, a Baker cyst results from another knee problem that causes swelling inside the knee. This makes the fluid inside the knee joint (synovial fluid) flow into the bursa behind the knee, causing the bursa to enlarge.

RISK FACTORS
You may be more likely to develop a Baker cyst if you already have a knee problem, such as:
• A tear in cartilage that cushions the knee joint (meniscal tear).
• A tear in the tissues that connect the bones of the knee joint (ligament tear). …show more content…
SYMPTOMS
A Baker cyst does not always cause symptoms. A lump behind the knee may be the only sign of the condition. The lump may be painful, especially when straightening the knee. If the lump is painful, the pain may come and go. The knee may also be stiff.
Symptoms may quickly get more severe if the cyst breaks open (ruptures). If your cyst ruptures, signs and symptoms may affect the knee and the calf, and they may include:
• Sudden or worsening pain.
• Swelling.
• Bruising.

DIAGNOSIS
This condition may be diagnosed based on your symptoms and medical history. Your health care provider will also do a physical exam. This may include:
• Feeling the cyst to check whether it is tender.
• Examining your knee for signs of another knee condition that causes swelling.
You may have imaging tests, such as:
• X-rays.
• MRI.
• Ultrasound.

TREATMENT
A Baker cyst that is not painful may go away without treatment. If you have a cyst that gets large or painful, treatment for the underlying knee problem will usually cause the cyst to get