The Treatment of Baker’s Cyst in The Presence of Knee Joint Effusion

A Baker’s Cyst or popliteal cyst is a fluid-filled sac that forms at the posterior aspect of the knee in the popliteal fossa between the semimembranosus and medial head of the gastrocnemius [1-3]. Adults between the ages of 35 and 70 tend to be affected more; the incidence is between 10% and 41%, while the prevalence is 5% [4, 5]. Women are more affected than men as they are more likely to develop arthritis [2, 6]. Baker’s Cyst is commonly found in association with knee joint disorders such as meniscus tears and osteoarthritis [2, 3, 6]. During its development, a connection between the knee joint and the cyst is formed and a one-way “valve effect” allows for the flow of synovial fluid from the anterior to the posterior aspect of the knee. The valve opens and closes via flexion and extension, respectively; fluid influx occurs during flexion due to negative intra-articular pressure and stops with extension due to positive intra-articular pressure [2, 7]. Common symptoms include a swelling or lump behind the knee; knee/calf pain; fluid accumulation around the knee; and clicking, locking, or buckling of the knee joint [2].