This depends primarily on your hemoglobin level before surgery. In young , healthy people if the level is above 13 , 99% of the cases require no transfusion. Even in bilateral cases , transfusion is required less than 10 % of the time. No transfusion is generally required with partial knee replacement. If your hemoglobin is below 13 , I would advise a series of Procrit (hematopoetin) injections usually given weekly for three weeks before surgery. These are quite expensive , but most insurance plans that have a drug benefit will pay for this. Another option is autologous blood donation. You deposit blood in the blood bank prior to surgery and use our own blood after surgery. Most insurances plans will cover the cost of this service; however , it has been shown to be less effective than preoperative Procrit injections. Revision (redo) surgery is more complicated than the initial joint replacement and often requires transfusion.