Prediction of Outcomes Following Total Knee Replacement

This is an observational study (not a treatment study) of pain and physical functioning after total knee replacement. The study includes 5 visits, 1 before surgery and 4 after surgery. You may be eligible if you are 50 or older,will soon be undergoing knee replacement surgery, do not have a serious heart condition or certain other medical conditions, and are not taking certain types of medications. The study includes evaluation of peoples' pain, physical functioning, medication use, and physiological responses to sensory stimuli such as heat and cold.