Knee > Water on the Knee

What is Water on the Knee?

Water on the knee, also known as knee effusion, occurs when excess fluid is produced in the knee when it is irritated, either from injury or overuse. If the fluid is in the bursa, which is in front of the kneecap, then water on the knee is a form of bursitis. It also can be produced by the synovium, a tissue around the knee that lubricates the joint and nourishes cartilage around the knee. All joints are surrounded by a sheath that is called a capsule. The synovium, which is the inner lining of the capsule, produces synovial fluid.

Water on the knee has been known as "housemaid's knee" because it often happens to people who kneel frequently or constantly while working or playing. Most sports and activities do not require kneeling, though baseball and softball catchers spend a great deal of time squatting. Though many injuries to the knee can cause excessive fluid in the joint, water on the knee is most often the result of overuse. Many conditions and injuries also can cause your knee to become irritated and lead to water on the knee. If it is caused by an injury or condition, it may be best for you and your doctor to find out the root of the problem and to have that problem resolved.

If left untreated, water on the knee is likely to persist, causing pain and discomfort.

There usually are three parts to an orthopedic evaluation: medical history, a physical examination, and tests that your physician may order.

Your physician likely will ask about your activities, which may have caused water on the knee. He will probably ask when the soreness or pain began, and if you have had any prior knee injuries.

Your physician can tell if there is excess fluid in your knee by pressing a hand on one side of your knee and then the other, looking for a bulge that indicates fluid.

TESTS

MRI (magnetic resonance imaging) can detect any excess fluid in the knee.

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