The skin of the affected area feels hot after knee replacement surgery, which is caused by the heat generated by the absorption of local hematoma in the joint or the local infection of the knee joint. 1. Most of the postoperative skin sensation after knee replacement surgery is caused by the absorption of heat from the hematoma in the joint, which is a normal postoperative physiological reaction. Sometimes it is accompanied by an increase in body temperature, but generally does not exceed 38.5 degrees, and is usually a low fever in the afternoon. 2. Another kind of knee joint infection can also cause the skin of the affected area to feel hot, accompanied by redness, swelling, pain and discomfort at the incision, sometimes there is local exudation, obvious swelling of the knee joint, and the inflammatory indexes of hematology are obviously elevated, which is often accompanied by high fever in the early stage. If the skin feels hot after knee replacement surgery, if it lasts for a long time or occurs repeatedly, you should pay attention to it and go to the hospital in time to find out the cause of the disease.