The common causes are: 1. poor wound drainage or local infection not treated in time; 2. systemic diseases, such as diabetes, vitamin C deficiency, anemia, malnutrition, etc. Treatment: Patients with systemic diseases should be treated reasonably for the original disease. For example, diabetes mellitus should be promptly given hypoglycemic drugs; anemia should be transfused, etc. For those with poor drainage or infection, drainage should be expanded and appropriate antibiotics should be given. For those whose sarcomeres are not freshly grown, it is appropriate to use external application of raw muscle. Prevention: Ask detailed history and conduct a comprehensive physical examination before surgery. Patients with diabetes mellitus should have their blood sugar controlled before surgery. It is important to ensure adequate drainage during surgery and not to palliate. Appropriate antibiotics are given postoperatively to prevent infection.