Baker's cyst

As a Baker 's cyst was originally the popliteal cyst ( popliteal: the popliteal belonging ) denotes the rheumatic patient. Today the term is often used as a synonym for all popliteal cysts, regardless of etiology. It is a protrusion of the posterior joint capsule of the knee joint between the gastrocnemius muscle ( medial head), and the musculus semimembranosus. It usually arises in the context of a damage within the knee joint, such as a lesion of the medial meniscus, a osteoarthritic cartilage change or even of rheumatoid arthritis. Chronic inflammatory processes, there is an increased production of synovial fluid, thereby providing a positive pressure in the knee joint is formed. The joint capsule is then at the point of least resistance ( locus of least resistance ) to the above Only to and forms a cyst.

Erstbeschreiber

William Morrant Baker, Surgeon, London, 1839-1896.

Symptoms

Swelling, fluctuation and possibly pain in the knee. Pressure on nerves and blood vessels in the popliteal fossa. This can occur in the area of the lower leg and foot numbness, paralysis and circulatory disorders. An increased probability of formation is associated with a rheumatic underlying disease. The Baker 's cyst can cause complications. If too much pressure it may rupture and cause such a compartment syndrome.

Diagnosis

The diagnosis is confirmed in addition to the clinical manual examination by ultrasound (sonography ) and possibly an MRI; it also differential diagnoses, such as aneurysms of the popliteal artery or vein are excluded.

Baker cyst in the sagittal MRI with passage point to the joint (arrow) between the semimembranosus and gastrocnemius medial head.

Baker cyst with MRI axial passage (arrow) between the semimembranosus and gastrocnemius medial head.

Therapy

Not every Baker 's cyst needs surgery, especially if it makes no complaints and is not large. The surgical removal (resection ) is not always useful, as the Baker 's cyst is formed by an overpressure in the knee joint, which is maintained by chronic inflammatory processes. A causal therapy of Baker 's cyst is thus composed of the knee joint. If the damage in the joint will be fixed, it may come to the regression of the cyst. Otherwise, there is a relatively high probability that the Baker 's cyst arises anew after its removal (relapse ). The surgery carries - like any surgery - a certain risk that an infection occurs.

In addition, the cyst usually can be treated or removed in an accident or orthopedic surgeons through a puncture.