Baker's cyst

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at May 17, 2016
StartBaker's cyst

Almost everyone experiences knee pain from time to time. It can be one of the most debilitating kinds of pain a person experiences, as it directly affects one's ability to walk, run, and perform basic functions. Knee pain is a symptom of many different disorders and medical diagnoses, one of which is Baker’s cyst. Another common name for a Baker’s cyst is a popliteal cyst.

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Definition & Facts

Baker’s cyst is defined as a cyst that forms behind the knee and often causes bulging, tightness, and pain in that knee. Typically, these cysts form as a result of existing injury in the knee joint. Arthritis or a tear in cartilage can often be the culprit, as they are both capable of producing an excess of fluid that builds up and causes the cyst to form. Though they’re usually painful, they don’t always cause pain, and even when they do, they can be successfully treated.

Symptoms & Complaints

Common symptoms of a Baker’s cyst include swelling behind the knee or in the leg which may or may not include pain. Knee pain without the existence of swelling can also be a symptom. Another common symptom is the inability to completely flex the knee due to tightness and aching in the knee. Typically, symptoms are intensified by long periods of exercise or standing. Clicking and popping of the knee joint is also a common symptom as well as locking up of the knee joint.

Another symptom which is less common is redness and swelling in the lower leg, particularly in the calf. This is caused by the cyst tearing open, resulting in fluid draining to the tissue of the lower leg and irritating it. Though Baker's cysts form as a result of knee injury, they are more often attributed to existing underlying illnesses. People with rheumatoid arthritis often develop Baker's cysts.

Causes

The body produces a lubricating fluid called synovial fluid that works to reduce friction in the joints and sockets of the knee, allowing it to swing smoothly when walking and running. When too much synovial fluid is produced, it can often build up too much in one area of the knee, resulting in a Baker’s cyst. An influx of synovial fluid is caused by several knee disorders and diagnoses, including but not limited to:

  • Arthritis which causes inflammation of the knee joint
  • Overuse injuries such as cartilage tears
  • Being overweight which puts stress on the knee joints, thus causing more wear and tear

More women develop Baker's cysts than do men. This is probably due to the higher incidence of rheumatoid arthritis among women than among men, and rheumatoid arthritis is a very common cause of Baker's cysts. These cysts are typically present in patients over 40.

Diagnosis & Tests

Physicians can often determine a Baker’s cyst with just a physical examination; looking at the knee and determining that it has developed a cyst. They will also ask questions about the patient’s medical history, when the swelling and pain started, and if the patient has had any cysts in the past.

Accurate diagnosis may require further tests because a Baker’s cyst often looks very similar to more serious illnesses and conditions, such as a blood clot, a tumor, or an aneurysm. Because physicians do not want to overlook these serious medical conditions, they will often order imaging tests such as ultrasounds, X-rays, and MRIs. These tests will let them know without a shadow of a doubt what exactly they’re looking at, which will help to set the patient’s mind at ease.

Treatment & Therapy

It’s possible that a Baker’s cyst will just go away on its own without any medical treatment involved, but this is not always the case. If the patient has an existing knee condition such as arthritis, the physician will treat that condition. This will typically cause the pain and swelling to subside for a period of time. Patients with such diagnoses will have to continue seeing their physician for checkups and updates.

If the patient’s Baker’s cyst is caused by knee overuse and the swelling and pain is not subsiding, the physician may attempt to drain the fluid from the cyst with a needle. Steroid medicine is also often given to patients with Baker’s cysts, as the medicine helps to reduce swelling.

When a patient has a Baker’s cyst, it’s necessary to keep as much weight off of the knee as possible. This is done with the use of a cane, a crutch, or a walker of some kind. Putting a snug but comfortable bandage around the knee is also very helpful in treating a Baker’s cyst. Though these methods usually work in removing a cyst, they’re not always successful. There are rare occasions in which surgery must be performed to remove the Baker’s cyst from the knee.

Prevention & Prophylaxis

Though it’s not always avoidable, there are a number of precautions and methods that can be practiced to limit the chance of developing a Baker’s cyst. The risk of having a Baker's cyst can be reduced by preventing knee injury, so it’s important for a patient to take care of his or her knees. This is done by wearing shoes that don’t cause strain on the knees, turning on the balls of the feet instead of with the knees, warming up and cooling down properly before and after exercise, and stopping physical activity immediately when a knee injury occurs.

If a patient has arthritis, he or she can avoid the development of Baker’s cysts by practicing RICE (rest, ice, compression, elevation): resting their leg, icing their knee, wrapping the knee snugly in elastic, wearing a knee brace, and elevating their leg at night when they sleep. It is also wise for patients with arthritis to reduce their activity level in order to reduce stress on the knee.