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There are a number of possible treatments for a knee cyst, with the chosen therapy depending on the exact type of cyst involved. A cyst is a sac, or pouch, which may be filled with fluid or a thicker substance. Knee cysts that have been caused by conditions such as injury, rheumatoid arthritis or gout may be treated with medication, and infected cysts often respond to antibiotics. It is important to treat any underlying causes, or a cyst may be likely to recur. A knee cyst that is causing symptoms and cannot be treated with medication may require surgical removal.
Most cysts that arise in the knee develop from what are known as bursae. Bursae are sacs located in the parts of joints where friction occurs. If joint overuse leads to injury, these bursae may fill with fluid, forming cysts.
The treatment of this type of knee cyst is usually medical, with a combination of rest, compression bandages and what are called non-steroidal anti-inflammatory drugs (NSAIDs). In cases where an existing disease, such as gout, causes a bursa to develop into a knee cyst, drug treatment focuses on the underlying condition. If a cyst becomes infected, antibiotic treatment may not be fully effective until the cyst has been drained using needle aspiration, where a syringe is used to draw out the cyst's contents.
One of the most common types of knee cyst is called a popliteal cyst, or Baker's cyst, which develops from a bursa at the rear of the knee joint. Usually, a Baker's cyst arises when structures inside the knee joint are injured, but it can also occur in patients with diseases such as osteoarthritis and rheumatoid arthritis. Symptoms of pain and fluid around the knee joint may be experienced. Treatment for this type of knee cyst may be carried out at home, using a combination of NSAIDs, rest, ice and compression bandages. If symptoms persist, a doctor may inject corticosteroid drugs into the knee to relieve the swelling and pain.
While Baker's cysts are not usually surgically removed, surgery may be required to repair any damage to the knee joint which may have caused the cyst to form. A long, thin instrument called an arthroscope, which is able to take pictures of the joint interior, is inserted into the knee. This enables the surgeon to discover any injured structures and repair them using tools associated with the arthroscope. Typically, a knee cyst which has not developed from a bursa, and which has symptoms that are not relieved using other methods, is most likely to require surgical removal.