Water on the knee is a general term used to describe excess fluid that accumulates in or around your knee joint. Your doctor may refer to water on the knee as a knee "effusion." Water on the knee may be the result of trauma, overuse injuries, or an underlying disease or condition.

The type of fluid that builds up in your knee depends on the underlying disease, condition or type of traumatic injury that caused excess fluid.

The pain and swelling associated with water on the knee don't have to limit your mobility. Self-care measures and treatment can help keep you on the move.