Incidence and risk factors The overall incidence of DVT after artificial knee arthroplasty will be 40% to 88% without appropriate preventive measures by drugs or physical means, and the risk of asymptomatic PE is as high as 10% to 20%, symptomatic PE is 0.5% to 3%, and the lethality rate is 2%; the incidence of proximal venous thrombosis above the level of the N vein is 3% to 20%, while The incidence of calf thrombosis is 40% to 60%, and the former has a significantly higher risk of PE than the latter. In the absence of appropriate prophylaxis, the incidence of DVT after artificial hip arthroplasty is 40% to 70%, and the incidence of fatal pulmonary embolism is 2% The risk of thrombosis in hip surgery is more than 5 times higher than in abdominal and thoracic surgery. Risk factors associated with DVT formation include age greater than 40 years, female, obesity, previous history of venous surgery or varicose veins, previous history of orthopedic surgery, smoking, hypertension, diabetes mellitus and coronary artery disease, congestive heart failure and chronic lower extremity swelling, postoperative braking, use of oral contraceptives and excessive blood loss or transfusion, and patients with malignancy. Vascular embolism may occur in the pelvic, thigh or calf veins. most DVT occurs in the calf and later extends to the thigh, but thrombus can also form in the pelvic veins and deep femoral veins alone. 80% to 90% of thrombosis is on the surgical side. DVT in the calf alone does not lead to PE formation, but 30% of calf vein thrombosis can extend proximally. The relationship between DVT and the development of PE and the timing of surgery has been inconsistently reported. However, several studies suggest that prophylactic treatment for DVT and PE should be maintained until after hospital discharge. Heparin anticoagulation in the early postoperative period is associated with a 45% complication rate. 6-23% of patients may have proximal extension of calf thrombus, and routine lower extremity venous Doppler ultrasonography can detect asymptomatic thrombosis, including proximal extension of calf thrombus, and only patients with proximal lower extremity venous thrombosis should be treated with anticoagulants throughout. The clinical presentation of DVT includes pain and tenderness at the thigh and calf, a positive Homans sign, unilateral lower extremity swelling or erythema formation, hypothermia and pulse rate. The clinical diagnosis of PE is based on unexplained chest pain, which can be evaluated with ECG and chest radiographs, arterial blood gases and coagulation analysis. Most PEs have no associated clinical signs, so ancillary imaging is needed for a definitive diagnosis in both DVT and PE. Lower extremity venography remains the “gold standard” for detecting DVT formation, and Doppler screening of lower extremity veins for thrombosis after TKA is highly sensitive, but is less helpful in the diagnosis of calf and pelvic vein thrombosis. Compared with venography, lower extremity venous ultrasound has a sensitivity of 79%, specificity of 98%, and accuracy of 97%. However, Muedock et al. found that Doppler sensitivity was only 40%, so excellent detection rates were not achieved in all centers. Therefore, Doppler ultrasonography can be a good screening test because it has a low disabling rate and low cost, but the accuracy is largely dependent on the operator’s experience. In addition, radionuclide imaging, enhanced CT scan, and echocardiography also have their own different diagnostic values. Prevention and treatment means Since DVT formation is insidious and often occurs after thrombus dislodgement with blood flow blocking the pulmonary artery, the preventive measures for PE are mainly to prevent the formation of DVT: 1. Basic methods: surgical operation requires good and fast, such as light and accurate movements; avoid intravenous injury; standardize the application of lower limb tourniquet; install the prosthesis once successfully; should not be completed in phase I with multiple joints; pay attention to cardiopulmonary function during and after surgery Functional monitoring and timely rehydration, avoiding dehydration to increase blood viscosity; postoperative elevation of the affected limb, encouraging patients to actively move their toes, deep breathing, and get down to the ground as early as possible; 2. Physical prevention methods: you can use elastic stockings or intermittent air pressure devices. The gradual decrease of pressure from the ankle to the groin of the elastic stocking can significantly reduce the stagnant blood after the venous valve. They are safe, simple, non-invasive, and can be used in combination with other prophylactic methods or alone in patients for whom anticoagulation is contraindicated. Intermittent pneumatic compression devices are usually used in combination with pharmacological prophylaxis in patients without contraindications who have high risk factors for deep vein thrombosis, as well as in patients with contraindications to anticoagulation therapy; 3. Commonly used drugs for the prevention of deep vein thrombosis: including common heparin, low molecular heparin, warfarin, etc. Absolute contraindication to drug anticoagulation: bleeding, if anticoagulation has not been started, it should be postponed; if it has been started, it should be stopped immediately, and rehabilitation should be stopped and braked at the same time. When prevention should begin: the coagulation process continues to activate for up to 4 weeks after major orthopedic surgery, and the risk of venous thromboembolism can last up to 3 months. The time frame for anticoagulation prophylaxis is longer after total hip replacement compared to total knee replacement, and the duration of deep vein thrombosis prophylaxis is generally not less than 7 to 10 d and can be extended to 28 to 35 d. Determining when prophylaxis should begin should be a trade-off; the closer to the time of surgery the drug is administered, the better the prophylaxis will be, but the higher the risk of bleeding. Deep vein thrombosis after arthroplasty can be treated with subcutaneous injection of low-molecular heparin 12 h before or 12 to 24 h after surgery or by starting an adjusted dose of warfarin after surgery. Second, the risk assessment of artificial joint prosthesis infection and contingency plan The occurrence of prosthesis infection in artificial joint replacement means the failure of surgery, so it is called catastrophic complications, therefore, it is important to prevent surgical infection. Basic principles: 1, from preoperative, intraoperative, postoperative whole process set prevention, each link can not be ignored; 2, medical and nursing cooperation, doctor-patient cooperation, clear division of labor, each division of responsibility; 3, take comprehensive measures, adhere to the rules and regulations, to achieve pragmatic and efficient. Specific measures include: control of susceptible factors and correct application of prophylactic antibiotics. Control susceptible factors 1. Preoperatively, patients with poor general condition (such as anemia, low immunoglobulinemia), combined with diabetes mellitus, rheumatoid arthritis and tuberculosis should improve their general condition and actively treat the original disease. Patients with tonsillitis, upper respiratory tract infection, and tinea pedis should be eliminated from local infection foci. Pre-operative prophylactic antibiotics should be used to eliminate potential lesions and minimize the preoperative hospitalization time of patients. 2. Intraoperative measures such as using laminar flow operating rooms, reducing the number of surgical visitors, using back-protective surgical gowns or air-isolated surgical gowns, wearing double-layer gloves, and covering surgical instruments can effectively reduce the chance of infection; perfecting preoperative preparation and improving surgical techniques with a view to shortening the operative time. The shortening of operation time can reduce the time of incision exposure to air and the time of tourniquet use to prevent the long-term hypoxic state leading to the reduction of the body’s resistance to microorganisms. Avoid rough operation during the operation and repeatedly rinse the wound with liquid containing gentamicin. 3. Postoperative joint drainage can improve the skin and joint cavity environment and reduce the incidence of deep infection. Maintaining negative pressure drainage tubes is usually one of the important factors in reducing blood accumulation in the joints and preventing joint infection. Clamp the drainage tube while the patient is performing functional training to prevent blood reflux in the drainage tube. Observe the nature, amount and color of the drainage fluid to detect any signs of bleeding in a timely manner. The drainage tube is usually removed within 24 to 48 h after surgery. Proper application of antibiotics From skin incision to incision closure, maintain adequate antibiotic concentration in the surgical field. The timing of administration is generally considered to be approximately 30 min before incision of the surgical site and 10 min before inflation of the tourniquet (i.e., best given during the induction of anesthesia). Another dose is given at 6 and 8 h postoperatively. In Europe and the United States, it is usually used for 3 to 5 d after surgery, and in China, it is usually used continuously for 1 to 2 weeks. However, long-term use of strong broad-spectrum antibiotics should be avoided as much as possible, and if the drug is used for a long time, it is advisable to take antifungal drugs at the same time to prevent fungal infection.