Fracture healing is a complex biological process and normal bone healing is influenced by both systemic and local factors. Systemic factors include hormones, drugs, age, gender, ethnicity, nutrition, etc., and their effects on bone are characterized as continuous, long-term and systemic. 1.Smoking Smoking is known to be hazardous to health, and its toxic factor is mainly the nicotine in tobacco, and the effect of smoking on fracture healing has received more and more attention. Recent studies have shown that nicotine inhibits vascularization and early revascularization of new bone and impairs osteoblast function. A larger body of literature suggests that the incidence of delayed fracture healing and nonunion is higher in smokers. It has been reported that the incidence of nonunion after ankle fusion is 16 times higher in smokers than in nonsmokers. In addition, smoking can also cause osteoporosis and extensive bone mineral loss. 2.Drugs Many drugs have effects on fracture healing, including non-steroidal anti-inflammatory drugs, steroids (hormones), sodium phenyltuin, ciprofloxacin, anticoagulants and other preparations. Systemic nutritional factors Fracture healing should not ignore the systemic nutritional status of the patient, some patients with bone nonunion is closely related to this factor.