In preoperative period, all eligible participants are admitted to the hospital for undergoing TKA. The detailed protocol, including how to rate visual analog pain score, times to take the blood for checking hematocrit levels, criteria for blood transfusion, time to measure the knee and thigh circumferences and plan of ambulation program, is informed again. The routine preoperative preparation is done. The participant is asked for answering preoperative Oxford Knee Score questionnaire. Participants' baseline characteristics are also recorded.