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Knee cyst
Last reviewed: 04.07.2025

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A knee joint cyst is a compacted elastic formation located in the back of the knee joint. The skin around the affected area is not fused with the surrounding tissues and does not change its color. When the knee is straightened, the cyst is more noticeable. If the knee is bent, the formation visually becomes smaller or disappears completely.
The larger the size of the formation, the more pronounced the swelling of the knee joint.
Causes of knee joint cysts
The causes of a knee joint cyst are not always obvious, sometimes such a pathology can develop without any apparent reason. At the same time, there are a number of factors that can provoke the development of such a formation as a knee joint cyst. Among them are the following:
- Knee joint injury;
- Meniscus injuries;
- Damage to articular cartilage;
- Chronic inflammatory phenomena in the synovial joint membrane;
- Deforming arthrosis;
- Patellofemoral syndrome, accompanied by such symptoms as stiffness in the kneecap, pain during physical activity, as well as when sitting with bent legs;
- Osteoarthritis;
- Rheumatoid arthritis.
Symptoms of a knee cyst
Symptoms of a knee cyst may include:
- Feeling of tightness in the popliteal fossa;
- Pain in the knee joint;
- Swelling in the knee area;
- Difficulty in bending or straightening the knee;
- Knee joint blockades.
Meniscus cyst
A meniscus cyst of the knee joint is most often found in young and middle-aged people. This pathology is provoked by excessive overload of the knee joint, which occurs during heavy physical exertion or active sports. As a result, a new formation with liquid contents appears in the meniscus cavity - a cyst, most often affecting the outer meniscus.
Symptoms of the occurrence of a knee meniscus cyst are painful sensations, which usually bother during physical activity, in particular, on the knee joint. In the meniscus cavity, a compacted formation is felt, the size of which can be from half to three centimeters.
Small meniscus cysts become invisible when the knee is bent and are clearly visible when the knee is straightened; they may not be palpable. If the cyst increases in size, it extends beyond the joint.
If you do not take timely measures to treat a meniscus cyst of the knee joint, it can lead to the development of osteoarthritis.
As an adjunctive treatment, the patient is advised to minimize the load on the knee joint. In case of severe pain, analgesics and nonsteroidal anti-inflammatory drugs are prescribed.
The main treatment is aimed at removing the meniscus cyst. However, complete elimination of the cyst can cause the development of arthrosis, so to remove it, it is advisable to resort to the method of arthroscopic surgery, which minimizes the risk of injury and complications due to the fact that the joint is not completely opened, but two small holes are made in it. Then, depending on the location and size of the cyst, it is dissected or the affected area of the meniscus is removed.
Diagnosis of a meniscus cyst of the knee joint can be made using ultrasound examination, arthroscopy or magnetic resonance imaging, as well as X-ray examination.
Parameniscal cyst
A parameniscal cyst of the knee joint is a complication of a common cyst that affects the ligaments. The size of such a neoplasm is quite large, the position of the knee does not affect the visibility of the cyst, and it does not disappear when it is extended.
Diagnosis of such a neoplasm is not difficult and is carried out by palpating the knee joint. Parameniscal cyst of the knee joint is the third stage of transformation of the meniscus cyst and requires surgical treatment. With timely treatment by a doctor, complete restoration of the functions of the knee joint is possible.
Ganglion cyst
Ganglion cyst of the knee joint is less common than others and is a neoplasm in the form of a ball or oval with a duct connecting it with the joint capsule and connective tissue membranes surrounding the tendons. The cyst cavity contains a transparent liquid. The reasons for the development of such a pathology have not been fully clarified, there is an assumption that it occurs with increased loads on the knee joint or its injury.
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Diagnosis of knee joint cyst
Diagnosis of a knee joint cyst is carried out taking into account the general indicators of the knee joint condition, since the cyst is a consequence of some of its primary pathologies. The most accurate methods for diagnosing a knee joint cyst are ultrasound examination and magnetic resonance imaging. A puncture of the cyst and analysis of its contents are also carried out.
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Treatment of knee joint cysts
Treatment of knee joint cysts includes conservative and surgical methods. In the first case, the patient undergoes a cyst puncture, its contents are pumped out with a syringe and steroid anti-inflammatory drugs are injected into the cyst. However, it should be noted that such therapy is not effective in all cases and often after the cyst contents are pumped out, it re-forms.
If the patient is diagnosed with the development of an inflammatory process in the knee joint, treatment should first of all be aimed at eliminating it. For this purpose, physiotherapy is used, as well as various medications to relieve inflammation in the form of ointments, tablets and injections.
Surgical intervention is indicated in cases where the cyst is large, restricts the mobility of the knee joint, preventing full knee bending, as well as in cases of recurring inflammation of the synovial membrane of the knee joint and when conservative therapy is ineffective.
During the operation, the knee joint cyst is excised under local anesthesia. The total duration of the cyst removal procedure is approximately twenty minutes. After five to seven days, the patient may be allowed to move around fully, after which the stitches are removed.