Baker’s cyst, is a fluid-filled swelling that causes a lump at the back of the knee, leading to tightness and restricted movement. The pain typically worsens if the patient fully flexes or extends the knee, or when he/she is moving about.
In most cases, people with a baker's cyst have existing knee joint problems, such as arthritis or a cartilage tear, which causes the knee to produce too much fluid, which may lead to a Baker's cyst. Treating the underlying cause can often alleviate the problem.
Though the cyst does not cause any log-term damage, it can be very uncomfortable. A Baker's cyst often gets better and disappears by itself over time but it may persist for months or even years before it goes. The cyst will not cause any long-term damage, although it can be uncomfortable and annoying. The symptoms may come and go. Long-term disability due to the cyst is very rare. The cyst can vary in size from a very small cyst to a large cyst that is a number of centimetres across. Rarely, a Baker's cyst can develop behind both knees at the same time.
Although people of any age may be affected, Baker's cyst most commonly occurs in children aged 4 to 7 years and in adults aged 35 to 70 years. However, Baker's cysts are much more common in adults than in children. Some people with a small Baker's cyst do not have any symptoms and the cyst may not always be found when the doctor examines the knee. The cyst may be seen in an MRI scan done for some other reason. Larger Baker's cyst are more likely to produce symptoms. You may be able to see or feel the swelling behind your knee. Sometimes you may also notice that the knee joint itself is swollen and it aches around the knee area. It may be difficult to bend your knee if you have a large Baker's cyst and the area behind your knee may feel tight, especially when you are standing up. Less commonly, you may feel a sensation of clicking or locking of your knee.
An ultrasound scan is a good investigation to show a Baker's cyst . Sometimes an MRI scan is used to confirm the diagnosis.
If you have an injury to the knee such as a meniscal tear, treatment of this may help to treat the Baker's cyst as well.
If you have pain and discomfort because of your Baker's cyst the doctor will decide on one or more of the following:
- Support stockings - these provide compression and may help to reduce the swelling.
- Non-steroidal anti-inflammatory drugs - these can help to relieve pain and may also limit inflammation and swelling.
- Ice - this may also help to reduce swelling and pain.. Apply the ice pack for 10-30 minutes. Less than 10 minutes has little effect. More than 30 minutes may damage the skin.
- Crutches - it may be necessary to use crutches because they help to take the weight off the affected leg while you are walking.
- Physiotherapy – to keep your knee joint moving and using strengthening exercises to help the muscles around your knee
- Fluid drainage - sometimes your doctor may use a needle to drain excess fluid from your knee joint to help to relieve your symptoms. However, it is common for the Baker's cyst to re-form over time. Cortisone (steroid) injection - this is sometimes used following fluid drainage, to reduce the pain and inflammation caused by the cyst. It does not prevent it from coming back again.