Doctor K: Baker’s cysts often recur after draining

DEAR DOCTOR K: I have a Baker’s cyst in my right knee. It has been drained twice and recurred. Are there any other treatments for it?

DEAR READER: I discussed your question with my colleague, Dr. Celeste Robb-Nicholson, a bone and joint expert who is the editor-in-chief of the Harvard Women’s Health Watch. A Baker’s cyst (also called a popliteal cyst) is a fluid-filled sac. It forms in the popliteal space, the hollow at the back of the knee joint.

A Baker’s cyst may occur as a result of a knee injury; it can also result from damage to the cartilage caused by arthritis. These conditions may cause cells lining the knee joint to produce excess fluid. If the fluid bulges into the popliteal space, a cyst can develop.

A Baker’s cyst may cause no symptoms at all or just a bulge at the back of the knee. But it can also cause pain, swelling and joint stiffness. Most often, those symptoms occur just in back of the knee. However, if a Baker’s cyst ruptures, it can cause severe pain, redness and swelling of the back of the thigh and calf.

Baker’s cysts aren’t dangerous and may go away on their own. But if a Baker’s cyst causes discomfort or interferes with normal activities, there are several things you can do. If the underlying cause isn’t addressed, it will often recur.

To bring down swelling, apply a cold pack or use a compression wrap. To reduce inflammation, take an over-the-counter nonsteroidal anti-inflammatory drug such as ibuprofen (Motrin, Advil, others).

Stress on the knee joint can increase inflammation. Rest your leg and keep it elevated when possible. When you’re up and about, use a cane or crutch.

Sometimes a Baker’s cyst needs to be drained. A needle is inserted through the skin into the cyst. Fluid is sucked out with a syringe.

If, as in your case, the cyst recurs despite these treatments, magnetic resonance imaging (MRI) should be done. This test can help detect the underlying cause of the cyst, which can then be directly addressed.