A swelling in the posterior part of the knee, more or less evident, can signal a joint problem: it is a Baker’s cyst. It is a sachet that contains excess synovial fluid and may be “lurking on a cartilage that is worn with an ongoing arthrosic process or a meniscal lesion. A cyst is more frequent in people with knees affected by arthrosis or meniscal degeneration rather than in healthy people who dedicate themselves to physical activity and overload of the joint,” adds Dr. Andrea Bruno, orthopedic and traumatologist at Humanitas.

Baker’s cyst is also called poplitea because it forms in the serous bags located in the posterior region of the knee. In case of arthrosis or cartilage lesion, the synovial fluid, which is indispensable to allow joint movements and reduce friction, is produced in excess by accumulating in the gastrocnemius-semimembranosus bags. This is where the cysts are formed, which can also be very voluminous, especially in patients with rheumatoid arthritis, and limit the articulation of the knee or flexing completely.

In some cases the cysts may also rupture: “Liquid transfer can lead to symptoms such as pain and swelling, which may lead to the appearance of venous thrombosis. However, it is sufficient to run an ecodoppler to exclude this possibility “, recalls Dr. Bruno.

The treatment

The cyst may not be symptomatic: “In the acute phase it is possible to intervene by applying ice, applying dressing and taking anti-inflammatory medications. Keep your knee at rest. What matters is the treatment of the condition that led to its formation, so it is necessary to intervene on the cartilaginous lesion or arthrosis “, the specialist points out. The surgery – concludes the expert – is performed only in selected cases, i.e. if the Baker cysts are voluminous and the patient does not respond to infiltrative therapies”.