Baker’s cyst - popliteal cyst of the knee
What is Baker’s Cyst and Definiton
A fluid-filled sac, also called a popliteal cyst, that forms at the back of the knee. The cyst develops when there is a tear in the synovial capsule (the membranous structure containing the fluid that lubricates the JOINT) that allows synovial fluid to leak into the ears of least resistance, hich is the popliteal fossa. The leaking fluid bulges out from the knee joint or forms a connection with a BURSA in the back of the knee. Either circumstance allows synovial fluid to collect, forming a noticeable lump behind the knee. A Baker’s cyst is soft to the touch and usually painless, though a large cyst can be uncomfortable or painful with movement or pressure.
NOTHING TO DO WITH BAKING
It is a common assumption that the term Baker’s cyst has something to do with being a baker, just as bricklayer’s shoulder tends to afflict bricklayers and tennis elbow develops in people who frequently play tennis (both conditions are forms of BURSITIS). But Baker’s cyst takes its name from the British surgeon who first identified it: William Morrant Baker (1839–1896).
When the cyst causes PAIN, the doctor may use MAGNETIC RESONANCE IMAGING (MRI) to determine whether other factors are involved. Occasionally a Baker’s cyst is a symptom of a torn meniscus (CARTILAGE in the knee), in which case treatment such as surgery may be necessary. Nearly always a Baker’s cyst eventually goes away without treatment.
See also ARTHROSCOPY; BURSITIS; KNEE INJURIES; OSTEOARTHRITIS; SYNOVITIS; TENDONITIS.
