Postoperative Pain Control After Periarticular Injection During Total Knee Arthroplasty

Overview

This study will evaluate the use of a local injection around the knee (periarticular) during total knee replacement (TKR) surgery to see if it reduces postoperative pain levels. The injection is a combination of various medications which are thought to reduce pain levels. Approximately 128 patients will participate in this study, half of the patients will receive this injection during surgery and the other half will receive a saline (salt water) injection. Pain scores after the surgery will be compared between the two groups. All patients will also receive a long-acting (24 hours) morphine injection during surgery. The hypothesis is that those participants receiving intrathecal Duramorph and local periarticular injections will have improved pain scores and reduced narcotic use when compared with intrathecal Duramorph alone at 48 hours postoperatively.

Data Collection: Data will be collected from the patient's medical record after discharge Variables include: * Age * Sex * BMI * UPAT score (Universal Pain Assessment Tool)- this is assessed hourly postoperatively by nursing staff on Orthopedics Unit * Patient's assessment of acceptability of pain * UPAT score as assessed by physical therapy pre and post therapy sessions * Duramorph dose * Time patient arrived on the Orthopedic Unit * Length of ambulation during physical therapy sessions * Amount of supplementary opioids (measured in morphine equivalents) * Use of anti-emetics * Any complications of surgery including venous thromboembolic event, cardiac event, bleeding event * Length of hospital stay The pharmacist will randomize patients to either study arm, prepare the injection and maintain dispensing records.