Where does the cyst come from?
In the popliteal region there is a bursa between the tendons of the gastrocnemius and semimembranosus muscles, which in many people communicates with the cavity of the knee joint. When excess fluid accumulates in a joint for any reason, it flows into this bag and returns poorly due to the valve mechanism. The bag gradually stretches and a cyst forms. Therefore, in adults, Baker's cyst is almost always secondary: it is accompanied by arthrosis, meniscus damage, rheumatoid or other arthritis. It occurs in children without joint pathology, usually does not require treatment and often disappears on its own.
- Communication between the articular cavity and the popliteal bursa
- Excess synovial fluid in the joint
- The valve mechanism makes it difficult for backflow
- In adults it is almost always secondary
- In children it is often primary and goes away on its own.
Causes and symptoms
The most common cause in middle-aged and older people is osteoarthritis of the knee joint, in younger people - damage to the meniscus and the consequences of injuries, and in case of systemic diseases - rheumatoid and other inflammatory arthritis. Complaints depend on the size: a small cyst is invisible, a medium one gives a feeling of a foreign body and bursting under the knee, especially with full flexion, a large one limits flexion and can compress blood vessels and nerves, causing swelling of the lower leg and tingling. It is typical that when the knee is straightened, the cyst feels denser, and when bent it becomes softer.
- Osteoarthritis of the knee joint
- Meniscus injury
- Rheumatoid and other arthritis
- Consequences of knee injuries
- A feeling of fullness under the knee
- Limitation of full leg flexion
- Swelling of the lower leg with a large cyst
Why is a cyst rupture dangerous?
A large cyst can rupture, and then the joint fluid pours into the tissue of the lower leg. Sudden pain, swelling, redness and tightness of the calf muscle appear - a picture very similar to deep vein thrombosis, which makes this situation dangerous. It is impossible to distinguish them without examination, and a mistake is fraught with serious consequences, so if there is sudden swelling and pain in the lower leg, you should urgently consult a doctor and perform an ultrasound examination of the veins. The effusion itself usually resolves within one to two weeks with rest and pain relief, but the diagnosis must be confirmed.
- Sudden pain and swelling of the lower leg
- Redness and tightness of the calf muscle
- Picture simulating deep vein thrombosis
- Mandatory ultrasound of the veins of the lower extremities
- Fluid absorption in 1–2 weeks
- Do not self-medicate for swelling of the lower leg
Diagnostics
The doctor examines the popliteal region in a standing and lying position, assesses the size and density of the formation, range of motion in the joint and signs of effusion. The main method is ultrasound of the knee joint: it confirms the fluid nature of the formation, determines the size and helps to distinguish the cyst from a popliteal artery aneurysm, soft tissue tumor and enlarged lymph nodes. MRI is prescribed to assess the condition of the menisci, cartilage and ligaments, that is, to find the cause. X-ray shows changes in arthrosis. In case of swelling of the lower leg, an ultrasound examination of the veins must be performed.
- Inspection of the popliteal fossa
- Ultrasound of the knee joint
- MRI of the knee joint to find the cause
- X-ray for suspected arthrosis
- Ultrasound of the veins of the lower extremities for swelling of the lower leg
- Inflammation tests for suspected arthritis
Treatment
The main principle is to treat the cause, not the protrusion. For arthrosis, this means weight loss, physical therapy with strengthening of the thigh muscles, load correction and therapy prescribed by a doctor; for inflammatory arthritis - basic treatment by a rheumatologist; If the meniscus is damaged, the issue of surgical treatment is decided. A small cyst without complaints is enough to be observed and does not require treatment. If the symptoms are severe, a puncture is performed to remove the contents and administer the drug, but if the cause persists, the cyst often forms again. Surgical removal is rarely used for large, recurrent and complicated cysts. Warming and rubbing in acute edema are contraindicated until thrombosis has been ruled out.
- Treatment of the underlying joint disease
- Observation for asymptomatic cysts
- Therapeutic exercise and strengthening of thigh muscles
- Weight loss
- Puncture with drug administration according to indications
- Surgical removal for relapses and complications
- Refusal to warm up until thrombosis is ruled out