Girls self-mutilation arm cut with a knife are mainly the following hazards: 1, the use of knife mutilation may cut the arteries, including ulnar and radial arteries, causing hemorrhagic shock, and even life-threatening; 2, cut with a knife may injure the nerves, including the median nerve, ulnar nerve, radial nerve, the situation, even if the nerve to do anastomosis surgery, but also may be left with a lifelong disability and lead to the hand activity is not working; 3, cut with a knife Cutting the arm with a knife may lead to the rupture of tendons or muscles, which will lead to muscle weakness and dyskinesia of the hand and forearm, resulting in the inability to carry out normal work and life; 4, self-inflicted injuries to girls using the arm cuts will lead to multiple scarring of the skin, resulting in cosmetic problems, and it is difficult to completely remove the scarring of these growths.