First degree: the skin is punctured by the fracture end from the inside out, with minor damage to muscle, subcutaneous tissue, and skin. Second degree: skin is cut or crushed and broken from the outside to the inside, with moderate damage to subcutaneous tissue and muscle. Third degree: extensive severe contusion of skin, subcutaneous tissue and muscle, often combined with injury to blood vessels, nerves. First degree open fracture, because the skin is opened by poking the fracture end from the inside out, the contamination is slight and the possibility of causing infection is small. In the second degree open fracture, the skin, subcutaneous tissue and muscles are ruptured from the outside to the inside, which increases the possibility of external dirt invading the wound and the possibility of infection, so the debridement should be thorough. In the third degree open fracture, the skin, subcutaneous f tissue and muscles are severely damaged and the soft tissues are obviously contused and necrotic, so a large amount of external dirt is brought into the wound and the possibility of infection is greatly increased. Soft tissue defects may be present after debridement. When the local skin is not enough to apply, it is necessary to cover the wound with a flap or free skin graft, or even to temporarily open the wound and leave it for second-phase repair.