Understanding Popliteal Cysts: Causes, Symptoms, and Treatment

Understanding Popliteal Cysts: Causes, Symptoms, and Treatment

Baker's cysts, also referred to as popliteal cysts, stand as one of the most common knee afflictions. These cysts, filled with fluid, create a protrusion near the back of the knee, leading to stiffness and discomfort. The condition owes its name to Dr. William Morrant Baker, a surgeon from the 19th century who first identified it.

Often triggered by internal issues within the knee joint, such as osteoarthritis or a torn meniscus, Baker's cysts emerge due to excessive fluid accumulation in the joint.

The majority of Baker's cysts respond well to non-surgical treatments, involving lifestyle adjustments and anti-inflammatory medication. In some cases, the cysts may even resolve without any intervention.

The knee, being the largest and most robust joint in the body, comprises the lower end of the femur (thighbone), the upper end of the tibia (shinbone), and the patella (kneecap). Smooth articular cartilage covers and safeguards the bone ends where they articulate to form the joint.

Synovial fluid, a clear liquid, fills the knee joint, functioning as a lubricant to minimize friction. Bursae, small sacs filled with fluid, cushion the joint and reduce friction between muscles and other surrounding structures.


In adults, Baker's cysts usually stem from injuries or conditions inducing swelling and inflammation within the knee joint, such as:

  • Osteoarthritis
  • Rheumatoid arthritis
  • Anterior cruciate ligament (ACL) tear
  • Meniscus tear
  • Other disorders affecting the joint tissues

The knee responds to inflammation by producing excess synovial fluid, which migrates to the popliteal bursa behind the knee, resulting in swelling and protrusion, characteristic of a Baker's cyst.


Some Baker's cysts remain asymptomatic and are incidentally discovered during a physical examination or MRI scan. When symptoms manifest, they may include:

  • Sensation of fullness or a lump behind the knee
  • Knee pain
  • Stiffness or tightness behind the knee
  • Swelling in the lower leg and knee

In rare cases, if the cyst enlarges significantly, it can impede blood flow in the leg veins or compress nerves, causing pain, swelling, weakness, or numbness. Occasionally, the cyst may rupture.

Symptoms of a cyst may sometimes be mistaken for those of a blood clot or deep vein thrombosis, a more severe condition. Increased discomfort and swelling in the leg warrant immediate medical attention to rule out a blood clot.


Most Baker's cysts resolve without intervention. Initial treatment for persistent cysts typically involves non-surgical approaches, such as:

  • Observation
  • Supportive footwear
  • Activity modification
  • Nonsteroidal anti-inflammatory drugs (NSAIDs)
  • Steroid injections
  • Aspiration

Surgical intervention is seldom necessary but may be considered if nonsurgical treatments fail to alleviate symptoms or if the cyst recurs.

Arthroscopy, performed under anesthesia, involves making small incisions in the knee joint and using a tiny camera (arthroscope) to guide surgical instruments. It's employed to address knee disorders like meniscus tears, which can contribute to Baker's cyst formation.

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