A Baker’s cyst, also called a popliteal cyst, is a fluid-filled swelling that develops at the back of the knee. It is caused by a problem with the knee joint or the tissue behind it. When an excess of knee joint fluid is compressed by the body weight between the bones of the knee joint, it can become trapped and separate from the joint to form a fluid-filled sac, referred to as a Baker’s cyst. The name is in memory of the surgeon, William Morrant Baker, who originally described the condition.
What are symptoms of a Baker’s cyst?
A Baker’s cyst may cause no symptoms or be associated with knee pain and or tightness behind the knee, especially when the knee is extended or fully flexed. Baker’s cysts are usually visible as a bulge behind the knee which is particularly noticeable on standing, compared to the other knee. They are generally soft and minimally tender.
Baker’s cysts can become complicated, by protrusion of fluid down the leg, between the muscles of the calf (dissection). The cyst can rupture, leaking fluid down the inner leg, sometimes giving the inner ankle the appearance of a painless bruise. Baker’s cyst dissection and rupture are frequently associated with swelling of the leg and can mimic phlebitis (inflammation of the veins) of the leg.
The swelling may cause:
• Pain in the knee and calf
• A build-up of fluid around the knee
• Occasional locking or clicking in the knee joint.
However, it may cause no symptoms at all, other than the lump.
What causes a Baker’s cyst?
Knee damage caused by a sports-related injury, or blow to the knee can lead to a cyst developing.
It can also originate by virtually any cause of joint swelling (arthritis), and a number of other health conditions, including:
• Osteoarthritis – usually brought on by age-related “wear and tear” of joints; it particularly affects the knees, hips, hands and big toe.
• Rheumatoid arthritis – a less common but crippling type of arthritis caused which results when the immune system attacks the joints.
• Gout – a type of arthritis that usually affects the big toe caused by a build-up of the waste product uric acid in the blood.
• Cartilage tears (such as when a meniscus is torn), and other knee problems.
Women are more prone to having cysts than men, probably because they are more likely to develop osteoarthritis and rheumatoid arthritis. It usually develops in people over 40 years of age, although it can affect persons of any age, including children.
How is a Baker’s cyst diagnosed?
Cysts can be diagnosed with the doctor’s examination, and confirmed by ultrasound; contrast dye into the knee called an arthrogram; or a magnetic resonance imaging (MRI) scan.
When to see your GP?
You should see your general practitioner (GP) if your cyst causes you problems and does not go away. They can usually diagnose a Baker’s cyst by examining your knee and asking about your symptoms.
They will also want to know if you have any associated health conditions, such as arthritis.
Further tests may be recommended to rule out other more serious conditions, such as a tumour or aneurysm (a bulge in a section of a blood vessel). These can include the ultrasound or (MRI) scans.
You can reduce the swelling and relieve any pain using over-the-counter painkillers, bandages, or an ice pack (a bag of frozen peas wrapped in a tea towel works well). Baker’s cysts often go with removal of excess knee fluid, in conjunction with cortisone injection. Medications are sometimes given to alleviate inflammation.
It’s important that any underlying condition is properly managed, as the cyst may go away when the condition causing it has been treated. In some cases, surgery may be needed to drain the cyst or to remove it.
When cartilage tears or other internal knee problems are associated with the condition, surgery can be the best treatment option. During a surgical operation the surgeon can remove or repair any damaged tissue.
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Leana Huntley is an English trained foot health practitioner attached to ALMAWI Limited The Holistic Clinic. Contact the Clinic at email@example.com or visit the Website at