<qa>  What is the dose of 0.5 bupivacaine solution injected into the localPatients who are undergoing unilateral total knee replacement TKR at Brigham and Womens Faulkner Hospital and meet all eligibility criteria will be informed about the study and asked if they would like to participate. Upon agreement, patients consent will be obtained and they will be randomly assigned to a treatment group. Patients in group one treatment group will receive a 30ml dose of 0.5 bupivacaine solution injected into the local anesthetic infiltration catheter immediately prior to its removal on postoperative day one. Patients in group two control group will receive no additional medication during local anesthetic infiltration catheter removal. 