What is Baker's cyst?
Baker’s Cyst (Popliteal Cyst) Introduction A Baker’s cyst, also known as a popliteal cyst, is a fluid-filled swelling that develops at the back of the knee, within the popliteal fossa. It is commonly associated with underlying knee joint pathology such as arthritis or a meniscal tear, which causes an overproduction of synovial fluid. This excess fluid can accumulate and extend into the popliteal space, forming a cyst. While Baker’s cysts are often asymptomatic, they can sometimes lead to discomfort, tightness, or pain, especially during full knee extension or activity. Anatomy and Pathophysiology The popliteal space is located behind the knee joint and contains important anatomical structures including blood vessels, nerves, and bursae. Baker’s cysts most commonly arise from the gastrocnemio-semimembranosus bursa , which normally exists between the medial head of the gastrocnemius muscle and the semimembranosus tendon. Under conditions of increased intra-articular pressure or inflamm...