Baker’s cysts, also called popliteal cysts, form when fluid collects behind the knee. Many people have no symptoms, while others may experience pain or stiffness when fully flexing or extending the knee. If the cyst bursts, the calf may swell, and more intense pain can develop. Generally, treating the cause of Baker’s cysts provides relief and alleviates the symptoms. There are many possible causes, but the vast majority are varieties of arthritis. Anything that can cause inflammation of the knee can cause a Baker's cyst.

Underlying Mechanisms

Synovial fluid surrounds the knee joint. This fluid is contained inside a membrane and plays an integral role in smooth movement of the knee. The synovial fluid can occasionally flow from the knee joint to the back of the knee, which causes swelling and a Baker’s cyst. This is usually the result of the body producing too much synovial fluid because of inflammation or knee injuries.

body pain Baker’s Cysts

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Degenerative joint disease or osteoarthritis affects 27 million Americans and can occur in any of the joints of the body. Osteoarthritis causes a break down in the joint cartilage, leading to pain, inflammation, and difficulty with movement. The inflammation may also lead to the production of proteins and enzymes that can destroy more of the cartilage, creating more joint damage and pain. Osteoarthritis primarily affects those over the age of 65 and is one of the leading causes of Baker’s cysts.

osteoarthritis Baker’s Cysts

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Rheumatoid Arthritis

Normally, the body’s immune system protects physical health by attacking viruses and bacteria. Rheumatoid arthritis is an autoimmune disorder where causes the immune system to target the joints, instead. This leads to inflammation and therefore a buildup of synovial fluid. If the inflammation continues unchecked, Baker’s cysts form, and the cartilage of the joint weakens. Loose and damaged joints are the logical progression. Rheumatoid arthritis appears more often in women than men and can develop at a younger age than in men.

types of Baker’s Cysts

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Septic Arthritis

Occasionally, disease-causing bacteria and microorganisms can spread from the blood to a joint. This may also be referred to as a joint infection. The infection causes inflammation in the affected joint, as well as pain and stiffness. Fever, headaches, and general weakness can accompany these initial symptoms. Artificial joints and chronic illnesses such as diabetes or rheumatoid arthritis are the leading risk factors for a joint infection. The infection can be lethal if the individual does not seek treatment quickly.

septic Baker’s Cysts

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Psoriatic Arthritis

Psoriasis is an autoimmune skin condition noted for causing scaly rashes and weak nails. Around 30% of people with psoriasis develop psoriatic arthritis as well. This form of arthritis may cause fatigue, other changes to the nails, and joint stiffness, particularly in the mornings. Psoriatic arthritis mainly affects the fingers and toes, though in rare instances it can attack the knees and lead to the formation of a Baker’s cyst. Permanent joint damage can occur in as little as six months without treatment.

arthritis Baker’s Cysts

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Juvenile Arthritis

Rather than a specific disease or disorder, juvenile arthritis encompasses many arthritis-related symptoms and issues that occur in children under the age of 16. Autoimmune disorders make up most arthritis that affects children. The most common form is juvenile idiopathic arthritis. Children may limp in the mornings and experience fatigue. Because the body’s immune system is attacking its own joints, there is pain and inflammation. The majority of juvenile arthritis cases are mild and easy to handle, though they can result in permanent damage.

juvenile Baker’s Cysts

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Gout is a type of inflammatory arthritis characterized by intense and sudden joint pain that can be crippling and last for days. It is caused by an overproduction of uric acid, which comes from the breakdown of purine, which foods such as beef, pork, poultry, beans, and wheat contain. Gout most often affects the big toe, but can also affect the ankles and knees. The swelling is noticeable and may be marked by redness of the affected joint.

gout Baker’s Cysts

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Often a long-lasting or chronic disorder, Fibromyalgia causes pain and often tenderness throughout the body. Women are twice as likely to be affected by fibromyalgia as men. Treatment is difficult because misdiagnosis of rheumatoid arthritis or thyroid disease is common -- the symptoms of the conditions are similar. Additionally, around 30% of those with rheumatoid arthritis also have fibromyalgia, further complicating diagnosis. The condition is also frequently associated with anxiety and depression.

thyroid Baker’s Cysts

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Another autoimmune disease, systemic lupus erythematosus causes the body’s immune system to attack healthy tissue. Symptoms vary wildly from person to person and can be mild or severe, leading to difficulties in diagnosis. The most common symptoms are pain, fatigue, and joint inflammation. The latter can be severe and lead to cysts. Women old enough to have children are nine times more likely than men to be affected by lupus -- those between 15 and 45 years old are most often affected.

lupus Baker’s Cysts

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Meniscus Damage

The knee has many small strips of fibrocartilage, menisci, which provide a cushion between the thigh bone and the shinbone. Almost any action the knee takes can tear the menisci. A clicking or locking of the joint can follow the damage. It is common for the injured individual to feel pain and inflammation that can worsen with added weight or pressure. The inflammation can lead to a Baker's cyst. Depending on the severity of the damage, the injured person may need surgery, though the knee can repair minor damage itself through rest and at-home treatment of inflammation.

Baker’s Cysts damage

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