The pain after knee replacement surgery usually lasts about a month. The most pain after knee replacement surgery is within one week after surgery. The most common symptom after knee replacement surgery is pain, because the prosthesis is placed in direct contact with the cartilage nerves in the joint cavity, so the pain is the most obvious after surgery, one week after surgery is the period of incision healing, and patients need to cooperate with the rehabilitation training in order to gradually alleviate the pain. Normally, one month after the operation, no oral medication is needed, and the patient can walk normally without the help of a walker. In the early stage after knee replacement, swelling may occur, and only when the swelling subsides can the pain be slowly relieved. It usually takes about a month, and the exact time it takes for the pain to go away depends on the recovery situation.