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Knee cyst
Last reviewed: 05.07.2025

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A knee cyst is a fairly common occurrence today. Mostly, it affects people who, due to their occupation, are subject to constant physical stress (people with heavy physical work, athletes) or a knee cyst manifests itself as a secondary disease against the background of arthritis, arthrosis and other similar diseases.
Causes of knee joint cysts
With hyperproduction of synovial fluid, it accumulates in the back of the knee. The accumulation of synovial fluid in turn causes many diseases of the knee joint. A knee cyst most often appears as a result of these diseases. Most often, the cause can be rheumatoid arthritis, osteoarthritis, osteoarthrosis. Less often, a knee cyst occurs due to damage to cartilage tissue, excessive physical exertion, traumatic injuries. The accumulated fluid begins to press heavily on the nerve endings, which leads to painful sensations in the knee and limited movement. Sometimes the causes of a knee cyst remain unknown. In children, this disease is not often observed, mainly older people are susceptible to it. To establish the exact cause of a knee cyst, the doctor prescribes an MRI or ultrasound of the knee joint, less often a puncture of the cyst is performed to examine the contents. Today, a knee cyst occurs in 17% of all cases of knee joint diseases.
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Knee joint cyst
A knee joint cyst is a benign tumor-like formation that forms on the back wall of the knee joint, the contents of the cyst are an accumulation of synovial fluid, clinically manifested by swelling of the popliteal fossa. This cyst connects with the joint cavity and its protrusion is actually similar to a hernia. The size of a knee cyst can vary from 2 mm to 10 cm, as a rule, it does not grow to huge sizes due to the fact that it bursts.
The knee cyst protrudes more when the knee is extended, and becomes smaller when bent. The skin in the area of the knee cyst usually has a normal, healthy color, there are no adhesions. The cyst occurs mainly due to metabolic disorders in the articular cartilage or due to obvious diseases of the knee joint (arthritis, arthrosis, synovitis, traumatic joint injuries); less often, the knee cyst occurs in children and adolescents.
Symptoms of a knee cyst
In the initial stages, a knee cyst does not manifest itself in any way, or manifests itself with weak feelings of discomfort. But when it begins to increase in size, it accordingly begins to press on nearby blood vessels and nerves (especially on the tibial nerve), which leads to painful sensations in the knee, numbness and tingling in the sole, a feeling of constant cold in the area below the knee. Movements in the knee become difficult and painful. In rarer cases, a knee cyst can press so much on the popliteal vein that it causes deep vein thrombosis, or varicose veins of the subcutaneous veins, which is accompanied by swelling, a feeling of heaviness and discomfort. Among all the acceptable cases of complications of a knee cyst, there is a rupture of its wall, the cause of which is high fluid pressure in the knee cyst itself. The rupture is accompanied by severe and sharp pain, redness of the skin, swelling and a local increase in temperature.
Meniscus cyst of the knee joint
The meniscus of the knee joint is a joint pad that consists of fibrous cartilage and acts as a shock absorber in the joint. When there is constant increased load on the joint (during constant sports or heavy physical work), a meniscus cyst can often occur. It is a fluid-like band formation inside the meniscus of the knee joint. A mucus-like substance accumulates in the meniscus tissue, which stretches the tissue of the meniscus itself and thus forms a cyst.
There are 3 degrees of meniscus cyst:
- Grade I – the cyst can only be determined by histological examination.
- II – the cyst affects the pericapsular zone, a protrusion can be seen on the outer part of the knee.
- III – cystic degeneration of not only the meniscus tissue, but also the nearby capsule and ligaments.
This disease most often develops in young and middle-aged people. The patient begins to experience pain in the joint, which intensifies with physical activity and disappears at rest. Palpation reveals a dense painful swelling on the lateral surface of the joint. The size of the meniscus cyst of the knee joint varies from 0.5 to 3.0 cm. To establish an accurate diagnosis, ultrasound and MRI of the knee joint, arthroscopy, and sometimes X-ray examination are used.
Cyst of the medial meniscus of the knee joint
A medial (inner) meniscus cyst occurs less frequently than a lateral (outer) meniscus cyst due to the fact that the medial meniscus is less mobile than the lateral one. The main symptoms of a medial meniscus cyst of the knee are pain localized in the inner part of the joint, pain when strongly bending the leg, and weakness of the muscles of the front of the thigh. This meniscus cyst tends to bulge in front or behind the inner side wall. The most effective method of treating a medial meniscus cyst is arthroscopy, the advantages of which are a quick recovery period, a small incision size, and no need for a plaster cast after surgery. Thanks to arthroscopy, the joint tissues remain intact, only a specific defect is eliminated.
Cyst of the internal meniscus of the knee joint
A cyst of the internal (medial) meniscus of the knee joint is less common than a cyst of the external (lateral) meniscus, because the lateral meniscus is more susceptible to stress. A meniscus cyst does not have the ability to connect to the joint capsule and protrudes in front or behind relative to the internal collateral ligament, less often protrudes through the thickness of the ligament. The main and dominant symptom of a knee cyst of the internal meniscus is pain, which appears when the joint is loaded and disappears at rest. When palpated, there is pain, a dense swelling ranging in size from a few mm to 3 cm or more. If a knee cyst of the internal meniscus is not treated for a long period, this leads to degeneration of bone tissue and, accordingly, to the development of deforming arthrosis. The most effective and popular method of treating a cyst of the internal meniscus is its removal using endoscopic arthroscopy, which is less traumatic for the joint and has a low risk of complications.
Parameniscal cyst of the knee joint
A parameniscal cyst of the knee joint is a meniscus cyst that has spread to the pericapsular zone and ligaments. The tumor-like formation reaches large sizes and does not disappear when the knee is extended. It is easy to palpate and diagnosis is not difficult. A parameniscal knee cyst belongs to the III degree of cystic degeneration of the meniscus and is a complex form, the treatment of which requires surgical intervention. In most cases, complex treatment, surgical intervention and subsequent physiotherapy give a positive result and the functions of the knee joint in patients are almost completely restored, which helps a person return to a healthy and full life without restrictions. But do not forget that a parameniscal cyst of the knee joint is often an advanced form of a common knee cyst, so a timely visit to the doctor, diagnosis and treatment of the disease in the early stages will help avoid surgical intervention.
Ganglion cyst of the knee joint
Ganglion cyst of the knee joint is not very common. This knee cyst is a benign formation that originates from the joint capsule and tendon sheath. These are spherical or oval formations with a duct in the middle that connects the ganglion cyst with the joint capsule and tendon sheath. These cysts are filled mainly with a liquid (less often gelatinous) transparent substance. When examined, the ganglion cyst is similar to a small water sac or looks like a tight and elastic tumor. It is impossible to name the exact and unambiguous cause of the ganglion cyst, but most often it appears in young women with hypermobility of the joint or as a result of traumatic injuries to the joint.
Synovial cyst of the knee joint
A synovial cyst is a disease characterized by a hernia or hypertrophy (enlargement) of the synovial membrane of the joint. Today, medicine is unable to name the exact cause of this disease, but there are several risk factors, such as osteoarthritis, rheumatoid arthritis, and traumatic joint injuries. Treatment of this knee cyst is surgical in most cases, since conservative treatment methods are not highly effective. The operation involves the complete removal of the synovial cyst and subsequent suturing of the weak point of the capsule with a special suture, which helps strengthen it. Today, a popular method is endoscopic removal of the knee cyst, due to the fact that this method is less traumatic and the recovery period is faster and more effective. But in any case, you should not delay a visit to the doctor, since the synovial cyst can rupture and this in turn will significantly complicate the entire process of treatment and recovery.
Cyst under the knee joint
A cyst under the knee joint (Baker's cyst) is a benign neoplasm that has a dense elastic structure and is characterized by stretching of the joint capsule and synovial membrane of the knee joint. Clinically, it manifests itself as an oval-shaped protrusion in the popliteal region. A Baker's cyst is similar in structure to a hernia, since its body does not consist of individual cells, but is connected to the joint capsule. The popliteal cyst protrudes most strongly when the knee is extended; when the knee is bent, it is less dense and less convex. When the popliteal cyst reaches large sizes, it can limit movement in the knee, clog veins (which leads to their varicose veins), or can press on nearby nerves and thereby cause numbness in the foot. When the cyst ruptures, pain occurs under the knee, fluid comes out of its cavity and spreads to the shin, causing its swelling. Surgical removal of Baker's cyst is currently the most effective treatment method and accordingly has positive results.
Diagnosis of knee joint cyst
Diagnosis of a knee cyst is performed by a traumatologist or orthopedist. A knee cyst is a secondary disease, so the diagnosis is based on the patient's medical history, complaints, laboratory and instrumental examination methods. Today, the most popular and accurate methods of instrumental diagnostics are MRI and ultrasound of the knee joint, they allow you to accurately determine the size and position of the cyst. Sometimes, in very severe cases, they resort to the use of arthroscopic diagnostics - through a small incision with an optical tube, the joint cavity is examined. A popular laboratory diagnostic method is a puncture of the knee cyst with subsequent examination of its contents. Thanks to accurate diagnostics and a correctly made diagnosis, the treatment of the knee cyst will have a positive result.
Treatment of knee joint cysts
Treatment of knee joint cysts involves a comprehensive approach to treating the disease. Several main points in treatment are highlighted, these are:
- Drug treatment. In most cases, drug treatment of knee cysts is not an effective method. Often, medications are prescribed by a doctor before or after surgery. In this case, drugs are prescribed that relieve inflammation and relieve pain, these are non-steroidal anti-inflammatory drugs such as Diclofenac, Ibuprofen, Ketoprofen, Indomethacin. These drugs are used in the form of tablets, ointments, injections. These drugs can relieve pain and inflammation, but they cannot completely cure a knee cyst, so if the cyst is not removed in time, complications and a relapse of the disease in a more acute form may occur.
- Surgical methods of treating a knee cyst include cyst puncture and surgical removal of the cyst. During a puncture, the cyst is pierced with a thick needle and the fluid is sucked out, then steroid (hormonal) anti-inflammatory drugs such as Berlicort, Triamcinolone, Kenalog, Diprospan are injected into the intertendinous bursa. Puncture gives a temporary result, since in the future, with loads on the knee joint, the cavity in the popliteal area will again be filled with synovial fluid and there will again be a need for a repeat puncture. Surgical removal is the complete removal of the cyst under local anesthesia. This operation lasts no more than 30 minutes. The patient can be discharged from the hospital in a day, and after about a week, the patient is already allowed to walk.
- Treatment of knee cysts with folk remedies is effective only if the cyst is in its primary stage and, accordingly, small in size. Folk remedies can also act as a method of additional therapy during drug treatment or during the recovery period after surgery. There are several popular and effective folk medicine recipes for treating knee cysts:
- Treatment with golden mustache tincture. Golden mustache must be crushed and filled to 34 of the volume of a three-liter jar, then filled to the top with water, closed with a tight lid and left for 20 days in a dark place to infuse. After the infusion is filtered and taken three times a day, 2 tablespoons 10 minutes before meals. The grass from the infusion can be used as a compress on the knee.
- Treatment with celandine. You need to finely chop 2 tablespoons of celandine and pour boiling water (100 ml), leave for 30 minutes and make a compress once every 2 days for 2-3 hours. This compress relieves inflammation and pain in the knee very well.
- Applications with elderberry and raspberry leaves. It is necessary to take elderberry and raspberry leaves in equal proportions, pour boiling water (100 ml), leave for 30 minutes. Put the mass of leaves on gauze, put it on the knee, put oilcloth on top and keep this compress for 2 hours. Repeat the procedure daily before bedtime.
When using traditional medicine recipes, it is worth remembering that not everyone can benefit from this or that treatment. A knee cyst is a tumor-like disease, so infusions and compresses cannot always give a good effect and completely get rid of the disease. Any type of traditional medicine treatment must be agreed with the attending physician, and only then used.
- Physiotherapy. Exercise therapy for treating a knee joint cyst is used exclusively during the period of remission, when there is no inflammation or pain in the joint. Otherwise, physical exercise can lead to pain and complicate the general condition of the disease. Exercises for exercise therapy for a knee cyst should be prescribed by a physiotherapist and at first they should be performed only under his supervision. To reduce joint pain, UV irradiation is used, the affected area of the joint is exposed to ultraviolet light. This method of therapy is carried out every day or every other day, in total no more than 5-6 sessions of such irradiation are used. To relieve inflammation, infrared laser therapy, low-intensity UHF therapy and high-intensity centimeter wave therapy are used. The entire course of these types of therapy includes no more than 10-15 procedures. Ultrasound diagnostics, hydrogen sulfide and radon baths are used to improve blood flow.
At home, the patient can do physical therapy (but only with the permission of a physiotherapist) and also do light self-massage of the knee.
Prevention of knee joint cysts
Methods of knee cyst prevention include exercise therapy during remission or physical exercises aimed at strengthening the knee muscles. It is also important not to physically overexert the knee joint, since most knee cysts appear due to excessive loads during heavy physical work or during sports. As a method of maintenance therapy, you can use such drugs to strengthen ligaments and joints as glucosamine sulfate, chondroitin sulfate, collagen, calcium and vitamin D. These drugs are highly effective in preventing diseases of the musculoskeletal system. It is important not to ignore any, even minor, pain symptoms in the knee, since a knee cyst can occur as a secondary disease, against the background of another disease of the knee joint.
In the modern world, a knee cyst is a fairly common disease and is mostly diagnosed at late stages, when surgical treatment methods need to be used. Therefore, you need to listen to your body and consult a doctor for any, even minor, symptoms of the disease. The sooner the disease is detected and diagnosed, the more effective the treatment and recovery of the patient will be.