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.
Acute swelling, which occurs after an injury, is due to fluid accumulation in and around the knee. There are two different types of fluid within the knee: blood and non-bloody fluids. Blood: Blood in the knee is usually associated with a fracture of the bone or cartilage. When bleeding is the cause of knee swelling, the onset is rapid and the swelling intense. Fluid usually accumulates within minutes of the injury.