The knee is a hinge joint that is responsible for weight-bearing and movement. It consists of bones, meniscus, ligaments, and tendons. The knee is fully designed to fulfill various amounts of functions, including the following:
- Provide enough stability.
- Helps to lower and raise your body.
- Allows twisting of the leg.
- Makes walking much more efficient.
- Supports the body in an upright position without the need for muscles to function.
A Baker’s cyst is a soft, fluid-filled lump that forms on the back of your knee. It is oftentimes referred to as a ‘popliteal cyst’ because they occur in the popliteal fossa, which is an area behind the knee containing nerves, veins, and arteries. A Baker’s cyst behind the knee develops because an injured knee produces extra synovial fluid, a clear liquid that runs through the cavities of the knee joint to decrease friction between the cartilage and joint.
The excess fluid can only flow in one direction, which increases pressure, inflammation, and swelling, and leads to a synovial-filled bulge. While the cysts may be painless in some cases, others experience moderate to severe pain, as well as a limited range of motion because of swelling, inflammation, and discomfort with knee extension. Therefore, these types of popliteal cysts may go away on their own. However, if the condition is left untreated, it can also worsen. From time to time, a Baker’s cyst ruptures, sending fluid down the inside of the calf and presenting as a bruise.
Baker’s cyst are usually considered asymptomatic. Most importantly, they are benign and so they should not be confused with a tumor or cancer. Furthermore, they do not turn into cancer.