Collagen is a natural protein component of the skin that acts like a scaffold and the main building block for cells, tissues and organs. About a third of the protein content in your body is made up of collagen, which is found in the bones, muscles, and tissues of the organs.
1 There can be the accumulation of fluid on the knee after an accident. 2  In most cases, the fluid is blood which can be through a fracture caused to the knee. 3  The swelling of the knee often takes place within some minutes of the injury occurring. 4  Gout and pseudo-gout can also cause fluid on the knee.
Water on the knee (or fluid on the knee) is a generic term for swelling in or around the knee joint caused by an excessive accumulation of fluid. The lining of the knee joint capsule, which encloses the knee joint, produces fluid that helps lubricate the moving parts of the knee joint and nourishes the cartilage. Certain diseases and injuries cause excessive joint fluid to be produced.