Yellow water from a broken knee is not infected pus, but is formed by the exudation of intertissue fluid. There are two treatment options for this condition: first, if the skin break is very superficial, first do a thorough debridement to remove all the surface dirt and filth, and after thorough disinfection, you can choose to expose the wound, not to get wet, and to reduce movement. The second, if the knee is broken and the surface skin is more defective or even the subcutaneous fat layer is exposed, it should be covered with Vaseline gauze, covered with a sterile dressing and bandaged, and changed every 3-5 days until the wound is healed, in addition to a thorough debridement.