A Baker's cyst, also known as a popliteal cyst, is a fluid-filled swelling that forms at the back of the knee. It is named after Dr. William Morrant Baker, who first described it in the 19th century. The cyst develops when excess synovial fluid, which lubricates the knee joint, accumulates and bulges out into a sac-like structure.
The most common cause of a Baker's cyst is an underlying knee condition, such as osteoarthritis or rheumatoid arthritis, that leads to increased production of synovial fluid. Other factors, such as a knee injury, inflammation, or overuse, can also contribute to the development of the cyst. As the fluid builds up, it creates a palpable lump at the back of the knee, which may vary in size and feel soft or firm to the touch.
While many Baker's cysts are painless, some individuals may experience discomfort, stiffness, or a feeling of heaviness behind the knee. These symptoms may worsen with activities that involve bending or putting pressure on the knee joint. In rare cases, the cyst can rupture, leading to sudden swelling, redness, and sharp pain in the calf area. If a rupture occurs, it is essential to seek immediate medical attention.
Diagnosing a Baker's cyst typically involves a physical examination and sometimes imaging tests, such as an ultrasound or MRI, to confirm the presence of the cyst and rule out other knee conditions. Treatment options for a Baker's cyst aim to manage symptoms, reduce swelling, and address the underlying knee condition. Conservative approaches include rest, applying ice packs, using compression bandages, and elevating the leg. Physical therapy exercises may be recommended to improve knee strength and flexibility. In some cases, aspiration (draining) of the cyst or corticosteroid injections may be considered to relieve discomfort.
