A Baker's cyst is a fluid-filled sac that forms behind the knee. It can cause symptoms such as a lump, pain behind the knee, swelling, stiffness, and difficulty moving.

This condition typically occurs in people who have a history of knee injuries, joint disease, or those who put excess strain on the knee joint, often due to intense physical activity.

Treatment for a Baker's cyst, also known as a popliteal cyst or parameniscal cyst, is managed by an orthopedic surgeon. Treatment may include rest, physical therapy, medication, or surgery.

physical therapist examining young man's knee

Common symptoms

The main symptoms of a Baker's cyst include:

Pain, discomfort, or a feeling of pressure behind the knee;
Pain that worsens with physical activity;
A visible lump at the back of the knee;
Difficulty straightening or bending the leg.

Small Baker's cysts typically cause few to no symptoms. However, they can grow over time if not treated properly, which may lead to the development of noticeable symptoms.

When a Baker's cyst becomes large, it may press on nearby blood vessels or nerves, resulting in additional symptoms such as tingling, weakness, or swelling in the leg.

Ruptured Baker's cyst

A Baker's cyst can rupture if it becomes too large or if there is a rapid buildup of fluid. When a cyst ruptures, it can cause symptoms like intense pain, redness, and swelling in the leg.

In this case, the swelling or lump behind the knee may disappear, and you might feel a sensation of fluid draining down the leg.

Symptoms of a ruptured Baker's cyst require emergency medical attention to confirm the diagnosis and begin appropriate treatment.

Confirming a diagnosis

A Baker's cyst is typically diagnosed by an orthopedic surgeon or rheumatologist. The diagnosis is based on symptoms and any history of knee injuries, trauma, or joint disease.

The doctor will also perform a physical exam and may request imaging tests such as an ultrasound or MRI of the knee to confirm the diagnosis.

Is a Baker's cyst serious?

A Baker's cyst is generally a benign condition and is not considered serious. However, it is important to confirm the diagnosis and, when necessary, undergo treatment to avoid worsening symptoms and potential complications.

Possible causes

The main causes of a Baker's cyst include:

Accidents or direct trauma to the knee;
Osteoarthritis or rheumatoid arthritis;
Meniscal injury or tear;
Benign tumors such as pigmented villonodular synovitis;
Frequent joint overload due to intense physical activity.

These conditions can cause an accumulation of synovial fluid within the bursa behind the knee, leading to the formation of a lump in the popliteal fossa. This is why it is also called a popliteal cyst.

Is a Baker's cyst cancerous?

A Baker's cyst is not cancer and does not increase the risk of cancer. It is a benign condition.

The cyst forms from a buildup of synovial fluid in the popliteal bursa, a fluid-filled cavity behind the knee that helps cushion the joint and reduce friction between bones, tendons, and muscles.

Treatment options

The treatment of a Baker's cyst is managed by an orthopedic surgeon and is recommended when the cyst causes symptoms. Treatment may include:

1. Rest

Resting and avoiding physical exertion are essential to prevent the cyst from growing or causing further pain.

If you experience pain, it’s important to avoid long walks or heavy lifting to prevent aggravating the cyst and to allow for proper recovery.

2. Cold compresses

Applying cold compresses can help reduce pain and swelling.

To do this, wrap an ice pack in a towel and apply it to the affected area for 15 minutes in the morning and evening to ease symptoms.

3. Anti-inflammatories

For intense pain, a doctor may recommend using non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen or diclofenac to reduce inflammation and alleviate pain.

4. Physical therapy

Physical therapy and rehabilitation exercises are important to strengthen the knee muscles and avoid putting unnecessary strain on the joint.

This treatment is effective in relieving symptoms, especially for cases of mild pain.

5. Treating associated conditions

Proper treatment of other joint-related issues, such as rheumatoid arthritis or osteoarthritis, is crucial to prevent the cyst from growing and causing more severe symptoms. A doctor may recommend treatment for these conditions or refer you to another specialist.

6. Corticosteroid injections

A corticosteroid injection directly into the cyst can relieve pain and reduce the cyst's size.

This procedure is usually recommended if symptoms persist despite taking medication or doing physical therapy.

It is most commonly used when the cyst is associated with other conditions, such as osteoarthritis or rheumatoid arthritis.

7. Needle aspiration of the cyst

In some cases, the cyst can be aspirated with a needle, which may be combined with a corticosteroid injection for further relief.

This treatment is often more effective in younger individuals without other joint-affecting diseases.

8. Surgery

Surgery may be recommended if other treatments are not successful. The procedure often involves correcting other knee abnormalities along with removing the cyst.

The surgery may be performed through an open procedure or arthroscopically, depending on the specifics of the case.

Potential complications

The primary complication of a Baker's cyst is pseudothrombophlebitis, which may occur when the cyst is large or ruptures.

This can cause symptoms similar to deep vein thrombosis (DVT), including swelling, warmth, and intense pain in the calf.

It is important to seek emergency medical attention right away if you experience symptoms of a DVT in order to prevent serious complications.

Baker's Cyst: Symptoms, Causes & Treatment