Local Injection of Local Anesthetic 24 Hours After Knee Replacement Surgery

The purpose of this study is to determine if an additional injection of local anesthetic immediately prior to removal of the local anesthetic infiltration catheter on postoperative day one is effective in increasing pain reduction, patient satisfaction or outcome measures following total knee replacement (TKR). It is hypothesized that an additional injection of 30ml of .5% bupivacaine solution immediately before infiltration catheter removal will provide pain reduction, patient satisfaction and outcome measures equal or superior to catheter removal with no additional injection. The target enrollment for this study is 50 participants, 25 in each of groups one and two.

Patients who are undergoing unilateral total knee replacement (TKR) at Brigham and Women's Faulkner Hospital and meet all eligibility criteria will be informed about the study and asked if they would like to participate. Upon agreement, patient's 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.

Members of both groups will be asked to complete Visual Analog Scale (VAS) pain and satisfaction surveys and also to track daily narcotic pain medication consumption during the first week postoperatively. Measures of swelling in the operative knee will be collected for members of both groups at the first routine postoperative appointment approximately one week after surgery. Swelling will be measured using a Perometer which calculates the total volume of the extremity in cubic centimeters (Pero-System, Wuppertal, Germany). Proprioception will be measured using a SD Balancer (Biodex Medical Systems, Shirley, NY) which calculates the the overall stability index (OSI) and compares it to age standardized data. Quadriceps strength using a handheld dynamometer. Outcome measures will be collected for members of both groups prior to surgery and at the second routine postoperative appointment between 6 weeks after surgery. Swelling will be also measured at the first post-operative visit 1 week after surgery. These data measures, as well as any complications will be recorded and used for analysis at the completion of the study.

The Principal Investigator (PI) will review all pain, satisfaction, narcotic usage and proprioception data on a weekly basis with the research assistant (RA) as it is collected. These checks will help to ensure validity and patient safety. Privacy and confidentially will be assured by using codes as deidentifiers in place of identifying information on any data sheets used in analysis. Data which identifies the patient will be made available only to investigators and stored only in a private folder on department computers protected with a firewall. No data will be shared outside of Partners. Adverse events will be promptly reported to the PHRC as per PHRC rules.