Baker cyst

The baker's cyst is a synovial fluid-filled protuberance in the popliteal fossa. It is usually the result of another illness. Read all about it!

Baker cyst

The Baker cyst is a fluid-filled protuberance in the popliteal fossa. It is caused by a weakness of the knee capsule and contains synovial fluid called synovial fluid. It is usually the result of another disease of the knee joint. It often causes no discomfort, but can press on vessels and nerves and then lead to complications. Read all about the development and treatment of Baker's cyst.

ICD codes for this disease: ICD codes are internationally valid medical diagnosis codes. They are found e.g. in doctor's letters or on incapacity certificates. M71

Product Overview

Baker cyst

  • description

  • symptoms

  • Causes and risk factors

  • Examinations and diagnosis

  • treatment

  • Disease course and prognosis

Baker's cyst: description

The Baker's Cyst, sometimes also called Baker's Cyst, owes its name to an English surgeon named William Baker. In the 19th century, he came across a cyst in the knee of some patients, more precisely in the popliteal fossa, and described this phenomenon first.

What is a cyst?

Cysts in medicine are cavities in the body that are not present under normal circumstances. They occur in various body tissues and organs (lungs, kidneys, liver, ovaries, etc.) and are either filled with fluid or, in the case of pulmonary cysts, with air. The Baker's cyst is in many cases harmless and initially often goes unnoticed, but with increasing size then usually occur problems.

How is the Baker's cyst formed?

Like any joint, the knee is surrounded by a connective tissue-like covering called the capsule. On the one hand, it contributes to stabilization, on the other hand, its inner layer produces the so-called synovial fluid, or Synovia for short, a kind of "synovial fluid" which reduces the friction on the articular surfaces. It also provides nutrients to the articular cartilage and contributes to mechanical cushioning.

When the knee joint is damaged or inflamed, the body responds by producing more synovial fluid. This increases the pressure in the joint capsule. If it is too big, the capsule can thinn out at a weak point and evacuate like a bag. Such a weakness lies in the knee capsule behind and then manifests itself as a cyst in the popliteal fossa. It typically develops on the inside of the popliteal fossa between the attachments of the gastrocnemius muscle (a calf muscle) and the semimembranosus muscle (a large posterior thigh muscle).

Who is affected by a Baker's cyst?

Especially in the elderly, a Baker's cyst often arises. Knee and other joint problems become more common with age and thus more likely to occur. Ultimately, however, a Baker's cyst can occur at any age. However, children are much less affected than adults. At a younger age, a Baker's cyst sometimes develops spontaneously, not as a result of knee damage. The reasons are not yet clear.

Baker's cyst: symptoms

The bigger the Baker's cyst, the more likely it will cause problems. Smaller cysts, however, often remain without symptoms. The size of a baker's cyst depends on how long it has developed and how it varies with the mechanical stress on the affected knee. The cyst and the load are related as follows: The body reacts to a heavy load on the already damaged joint with an increased inflammatory reaction and thus an increased formation of synovia.

Accordingly, a Baker's cyst swells in addition, for example, by sports or physical work, in addition. Conversely, it will become smaller again as soon as the patient spares his knee for a few days. As long as you do not treat the underlying disease, the Baker's cyst usually increases in volume and eventually causes symptoms. These may include:

  • a palpable swelling in the popliteal fossa as soon as the Baker's cyst has reached a certain size (from about 2 cm).
  • the noticeable movement of fluid under the skin of the popliteal fossa. This phenomenon is referred to in medicine as fluctuation.
  • first an indefinite pressure feeling at the back of the knee by the Bakerzyste. The popliteal and upper calf can also become increasingly painful.
  • Circulatory disorders and feelings of numbness to paralysis of the lower leg and foot.

The symptoms mentioned in the last point occur when the Baker's cyst presses on vessels and nerves in the area of ​​the popliteal fossa.

The burst Baker's cyst

Complications arise especially when the Baker's cyst ruptured, so tearing. This can happen if it gets too big and the pressure in relation to the wall thickness has reached a critical level. If the person then bends the knee, the thinned-out wall of the cyst can no longer withstand the pressure increase and ruptures.

Once the baker's cyst has burst, the synovium will leak into the surrounding tissue, causing inflammation and additional pain. Following gravity, the leaked synovial fluid enters the calf muscles and in some cases even to the region around the ankle.

Due to the inflammation and swelling caused in the tissue pressure builds up there, which can not escape. Physicians then speak of a compartment syndrome. This presses on nerves and smallest blood vessels and can have serious consequences up to the loss of the lower leg, if not treated in time surgical treatment.

Baker's cyst: cause and risk factors

An abnormally increased production of synovia in the knee capsule occurs especially when the knee joint is damaged. Be it through wear, injury or inflammation. The most common causes of the occurrence of a Baker's cyst are:

  • Osteoarthritis: As people age, many people experience wear and tear on their joints. The knee joint is particularly stressed during physical activity.
  • Meniscal damage: If one of the two cartilage discs breaks in the knee joint, for example as a result of an accident, more synovial fluid is produced by the irritation. This also affects younger people.
  • Arthritis: Inflammation in the knee joint is often caused by rheumatoid diseases. In rarer cases however also bacteria are the triggers.

The two biggest risk factors for a Baker's cyst are a higher age, as well as, among younger people, activities and sports that involve a high knee load. Occasionally, operations are the trigger of a Baker's cyst. Knee-TEP surgery and cruciate ligament reconstructions would be examples of this.

Baker's cyst: examination and diagnosis

For the most part, patients only seek advice from the orthopedist when the Baker's cyst is already larger and the first symptoms appear. Sometimes, however, it is also incidental when the knee is examined for other reasons. The doctor first asks for the medical history of the patient. He is particularly interested in whether problems with the knee joint have occurred in the past. The preliminary talk is followed by a physical examination in which, in the case of a Baker's cyst, a plump, bulging, elastic swelling can usually be felt in the popliteal fossa.

But there are other reasons for such swellings such as tumors or thrombosis. Therefore, for the safe diagnosis of a fluid-filled cyst. Popliteal and calf muscles examined with an ultrasound machine. On the one hand, this allows the examiner to recognize the Baker's cyst in the knee as a fluid-filled capsule bulge; on the other hand, it can also detect any swelling in the calf muscles due to leaked synovia.

Another method of examination is magnetic resonance imaging (MRI), which can be used to detect fluid accumulation in the body. An MRI is more accurate than the ultrasound examination and less dependent on the experience of the examiner. It also provides additional information on possible meniscal damage or joint wear. However, this examination method is also much more expensive and is therefore not used by default.

If the diagnosis "Baker's cyst" is established, additional examinations may follow to track down the causative disorder.

Baker's cyst: treatment

Therapy differentiates between symptomatic and causal approaches. Symptomatic methods only relieve the symptoms caused by a baker's cyst, while causal therapy targets the root cause of the condition. Not every baker's cyst needs to be treated. As long as she does not cause any problems, one can also wait.

Baker's cyst: therapy with drugs

To treat the pain, the classic drugs from the field of nonsteroidal anti-inflammatory drugs (NSAIDs) are available. This group includes, for example, diclofenac and ibuprofen. In addition to relieving pain, they also counteract inflammation. Furthermore, there are so-called Cox-2 inhibitors, which act similar to the classic NSAIDs, but have fewer side effects on the gastrointestinal tract.

Cortisone is also a naturally occurring hormone (cortisol) in the body, which has numerous effects, including a strong anti-inflammatory. Since it has significant side effects at high doses or long-term use, it must be used wisely. In the case of the Baker's cyst, the doctor can inject cortisone into the knee joint so that the active substance temporarily stops the inflammatory processes there. But this should not happen more than three times a year.

Finally, there is the possibility to inject hyaluronic acid into the joint. That sounds contradictory, because hyaluronic acid is indeed the main component of the Synovia, of which there is actually too much. However, hyaluronic acid improves the quality of cartilage tissue in the joint, the damage of which is often the cause of a baker's cyst. In this respect, the use of this substance can achieve long-term positive effects.

Baker's cyst: physiotherapy

Various physiotherapy measures help to alleviate the symptoms of a baker's cyst. For example, there are special strength and leg axis training or water training - methods that help the joints to strengthen the muscles around the knee joint and reduce the stimulation situation. However, depending on the underlying disease, it is always necessary to ask the doctor first whether physiotherapy is an option.

Baker's cyst: puncture

It is possible to puncture a baker's cyst and use a syringe to aspirate its liquid contents. This may be temporary relief for the patient, but it is very likely that the cyst will soon fill with synovial fluid and swell again...

Baker's cyst: surgery and thermotherapy

To treat a baker's cyst sustainably, the actual cause must be treated. For many patients, this sooner or later means an operation on the knee joint, for example to repair damage to the cartilage or the menisci. Such an intervention can be open or, minimally invasive, via a joint mirroring. The actual cyst is usually not removed, it goes back to elimination of the cause of alone. However, if rheumatoid arthritis is the cause, the surgeon removes the entire Baker's cyst.

More recent techniques rely on bipolar current, which is applied to the cyst wall by means of electrodes, after having punctured the cyst contents. The resulting heat shrinks and clogs the cyst wall, preventing Synovia from overflowing.

Baker's cyst: homeopathy

Homeopathic approaches to the treatment of a Baker's cyst are concomitant with the above-mentioned therapy methods in question. For example, they help some people following an operation by supporting the healing process. A commonly used remedy in homeopathy that is also used in the Baker's cyst is arnica C30.

Baker's cyst: disease course and prognosis

The Baker's cyst in many cases does not cause any problems as long as it is still smaller. Accordingly, therapeutic measures are only required if symptoms occur or if there is a risk of complications. Since the cyst in the knee is usually only the symptom of another disease and it also often increases creeping in size, sooner or later the need for a therapy arises.

Although symptomatic treatments can alleviate the symptoms and delay surgery, spontaneous regression of the cyst is not expected. Many patients will only be treated with surgery Baker cyst permanently going on.


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