Updated on 6/20/2005
You're describing a condition known as "water on the knee" in which fluid accumulates in or around the knee joint causing swelling and pain. Usually this occurs as the result of a past injury that has led to scarring, which obstructs lymphatic drainage. To determine the cause of your problem, you and your physician will have to discuss your history of injuries to identify one that may be responsible as well as any of your current activities that may play a role. To locate the scarring you may need an x-ray or MRI (magnetic resonance imaging) scan of the knee. In the meantime, a compression bandage might help, and you could consider acupuncture for treatment.
However, sometimes water on the knee can be the result of overuse - the term "housemaid's knee" was coined to refer to this condition among domestic workers who spent hours each day on their hands and knees scrubbing floors. "Housemaid's knee" is also known as prepattellar bursitis - an inflammation of the bursal sac located between the kneecap and the overlying skin. Repetitive pressure, gout and infection are the most common causes. However, this typically resolves within two weeks if you avoid putting pressure on the knee.
You can try topical DMSO (dimethly sulfoxide) available at health food stores or on the Internet. DMSO penetrates the skin and targets pockets of inflammation, where it stimulates healing. Make a 70 percent solution by diluting a 100 percent solution with distilled water. The mixture will get hot so allow it to cool down before use. Apply it to the affected area with absorbent cotton and let it dry. You can apply the solution three times a day for three days. If you don't see any improvement, stop using it. If you do notice a difference, begin to cut back to twice a day for three more days then once daily for the last three days. After that, your body can continue the healing process on its own.
Osteoarthritis can also cause water on the knee. This happens if the joint becomes inflamed and the membrane (or synovium) which lines the joints secretes an excess of synovial fluid. If you have arthritis, I recommend reading The Arthritis Cure by Jason Theodosakis, MD, Brenda Adderly and Barry Fox, PhD. (St. Martin's Press, 1997) and, for treatment, consider using glucosamine sulfate (1,500 mg daily) with or without chondroitin sulfate (1,200 mg daily).
Andrew Weil, M.D.