Knee replacement surgery is a risky operation because it is a major surgery, which is more traumatic and takes longer to perform. During the operation, due to the large trauma and the need for osteotomy, there will be a large amount of bleeding, which will cause a drop in circulation and may lead to shock, and even if blood is replaced, there may be allergies and transfusion reactions, so there is a greater risk. In addition, during the operation, fat particles may enter the venous circulation through the ruptured blood vessels and finally reach the heart and then the lungs from the heart, resulting in pulmonary embolism, which may also lead to respiratory failure and affect life safety. After the surgery is completed, it may cause deep vein thrombosis in the lower extremities as well as wound infection due to the longer bed rest time required. However, this is only relative. For patients with poor knee function that affects the quality of life, knee replacement is very necessary and the benefits far outweigh the disadvantages.