In recent years, the orthopedic department of our hospital has gained rapid development, and the number of patients coming to us gradually increases, especially the number of joint replacement patients and hip fracture surgery patients increases significantly, and these patients belong to the very high-risk cases of deep vein thrombosis (DVT) and pulmonary thromboembolism (PTE), which are prone to occur. Several cases have left us a painful lesson, so we should pay attention to this “hidden killer”. Zhang Peng of the Department of Joint Surgery, Qilu Hospital of Shandong University (Qingdao) has reported in more and more literature that the incidence of DVT after major orthopaedic surgery in China is comparable to that in western countries, but the current attention to the prevention and treatment of DVT in China is much lower than that in foreign countries, and after more than 50 orthopaedic experts from all over China have worked hard for more than a year to formulate the “Expert Recommendations for Prevention of Deep Vein Thrombosis after Major Orthopaedic Surgery”, which was published by the Chinese Academy of Engineering in Beijing on Nov. 13, 2005. On November 13, 2005, a press conference was held in Beijing by dozens of medical experts in related disciplines, including Prof. Wang Penghuan and Prof. Dai Mianrong, academicians of the Chinese Academy of Engineering, introducing the diagnostic methods, preventive measures and matters to be noted in the process of prevention of deep vein thrombosis and pulmonary embolism in orthopedic surgery. It provides an important reference for clinicians in China to prevent the occurrence of deep vein thrombosis after major orthopedic surgery. About 50%~80% of DVT can have no clinical manifestation, but it is extremely harmful because it can be complicated by fatal PTE and distant lower limb deep vein insufficiency. Both timely detection and treatment depend on the early detection and correct diagnosis of the disease state. Currently, it is not possible to clinically identify high-risk cases based on the clinical, genetic, biochemical, and immunological predictive features of DVT and to prevent patients at a hierarchical level based on individual risk factors; therefore, active prevention should be performed in all patients undergoing major orthopedic surgery of the lower extremities at this stage. The comprehensive preventive measures proposed in the Recommendations include the following: Basal prevention measures: (1) operations around the extremities or pelvic adjacent veins should be performed gently and delicately to avoid intravenous injury. (2) When elevating the affected limb after surgery, do not place a separate pillow in the rouge fossa or under the calf to avoid interfering with deep calf venous reflux. ③Encourage patients to start frequent active foot and toe activities as early as possible, and make more deep breathing and coughing movements. ④ As early as possible to leave the bed, the lower extremities can wear step-by-step compression elastic stockings. Mechanical prophylaxis: including plantar venous pump, intermittent inflatable compression device and stepwise compression elastic stockings, all of them use mechanical principle to accelerate venous blood flow in lower limbs and reduce the incidence of DVT in lower limbs after surgery. However, in clinical trials, antithrombotic drugs were more effective than nonpharmacologic prophylaxis, so these methods were used only in patients with high-risk bleeding factors or in combination with antithrombotic drugs to improve their efficacy. Pharmacologic prophylaxis: ① conventional dose of low-molecular-weight heparin given subcutaneously starting 12 h before or 2-4 h after epidural catheter removal at 12-24 h after surgery; or half of the conventional dose starting 4-6 h after surgery and increasing to the conventional dose the next day. ②Pentosan sodium: 25mg 6-8h postoperatively (not yet available in China). The dose should be monitored to maintain the intemational normalized ratio llNR at 2 0-2.5, not to exceed 3.0. The duration of any of the above anticoagulation methods is usually not less than 7-10 d. The combined application of the above drugs may increase the possibility of bleeding complications, so the combined use is not recommended. Due to the large number of patients with major orthopedic surgery, in order to ensure the quality of medical care for patients and reduce medical risks, we should change the concept of insufficient awareness of deep vein thrombosis, actively prevent the formation of deep vein thrombosis and reduce the occurrence of pulmonary embolism in accordance with the requirements of the Expert Recommendations for the Prevention of Deep Vein Thrombosis after Major Orthopedic Surgery, and be able to detect and treat deep vein thrombosis early.