From the recovery room you will go to the Clinical Research Center (CRC) which is a special part of the hospital where research is undertaken. During your stay at the CRC you will have the ability to push a button on a small infusion pump to give yourself more medicine through the tube to your nerves if you have pain. If this does not help enough, you will take pain pills to help. And if this does not help enough, you will be given opioids (strong pain medicine like morphine) into your IV. Each morning after surgery, the medicine in your little infusion pump will be replaced by either (1) more medicine, or (2) salt water, or "normal saline". The pharmacist will determine this randomly—like flipping a coin—and neither you nor the doctors/nurses caring for you will know which you have. This is to keep any of us from inadvertently/unconsciously affecting the results of the study. However, if you have pain that is not controlled with pain pills, you will be switched back to the regular medicine to improve your comfort until the following morning. You will undergo physical therapy and following this you will be checked to see if you are ready to go home. When you are ready to go home beginning on the third day after surgery, you may go home with the little infusion pump and the tube that goes to the nerves of your knee. One of the study physicians will call you each night to ensure that you are comfortable for the first 7 nights after your surgery, and you will be given the phone and pager numbers of a physician available for you to contact 24 hours/day, 7 days/week. When the medicine runs out or in the fourth evening following surgery, whichever comes first, your catheter will be removed. The pump is disposable, so it can be thrown away. A physician will call you the two nights after the catheter comes out to ensure that you are comfortable.