“Water on the knee” is one of those phrases we hear that harkens back to years ago, like lumbago (low back pain) or causalgia (Reflex Sympathetic Dystrophy (RSD); now also known as Chronic Regional Pain Syndrome (CRPS)). Simply put, “water on the knee” is swelling (also called “effusion”) of the knee.
Like lumbago, for years people associated “water on the knee” with aging and related degenerative changes. For lack of a better term, years of wear and tear. A recent article on Medical News Today, however, points out that “water on the knee” is not just a sign of aging or degeneration.
In fact, the article states that trauma and injury can be causes of the knee problem. Interesting, doctors can study the fluid which is drained from the swollen knee, to gain some insight on the condition involved. For example, if the swelling is due to injury or trauma, there may be blood in the fluid. Bacteria in the fluid could point to infection as the source of the swelling. Some types of acids in the fluid may cause doctors to lean toward other causes, such as gout.
Regardless of the cause of the swelling, “water on the knee” is not something that stopped in years past.