Infection after artificial knee replacement is a growing concern for doctors and patients. In the hospital, doctors are very strict in controlling the infection rate from the pre-surgery protection to the aseptic operation during the surgery, and strive to minimize the infection rate. Currently, the international incidence of infection after artificial knee replacement is 1%, while the post-operative infection rate at Beijing 301 Hospital has dropped to 0.1%, far below the international level. Although the rate of infection has dropped significantly, it is only a probability and it is a matter of 0 and 1 for a specific patient who is either infected or not infected. So, who is prone to infection after knee replacement? First, patients with weak resistance. When a patient has a weak systemic immune system and a weak resistance, once bacteria enter the body, they are unable to “fight back” and are unable to resist the attack of these bacteria, making them very susceptible to infection. Secondly, patients with infections in other parts of the body during surgery. This is a case where the patient’s own resistance is still good, but the risk of infection is still relatively high in the face of a large army of attacking bacteria. For example, a patient with an ulcer before surgery is prone to infection during surgery. Therefore, it is important to eliminate these inflammatory bacteria before performing knee arthroplasty. Third, patients whose constitution belongs to those who are susceptible to infection. This is a case where the patient’s physique is such that bacteria can easily multiply and grow despite their own resistance, most commonly in diabetic patients. Because of the high concentration of blood sugar in the body of diabetic patients, these blood sugar is an important nutrient for bacteria. Therefore, diabetic patients who do not have good control of blood sugar are also very prone to infections.