Abstract
Total knee arthroplasty is associated with early postoperative pain. Appropriate pain management is important to facilitate postoperative rehabilitation and positive functional outcomes. This study compares outcomes in TKA with three techniques; local infiltration analgesia, single shot femoral nerve block and intrathecal morphine.
Methods
Forty-five patients undergoing elective primary Total Knee Arthroplasty (TKA) with were randomized into one of three groups in a double blind proof of concept study.
Study arm 1 received local infiltration analgesia ropivacaine intra-operatively, an elastomeric device of ropivacaine for 24 hours post-op.
Study arm 2 received a femoral nerve block of ropivacaine with placebo local infiltration analgesia and placebo intrathecal morphine.
Study arm 3 received intrathecal morphine, placebo femoral nerve block and placebo local infiltration analgesia. All patients received standardized pre-operative, intraoperative and Post-operative analgesic medication.
Participants were mobilized at 4 hrs, 24hrs and 48 hrs post operation. Range of Motion, Visual Analogue Scale (VAS) pain intensity scores and two minute walk test and Timed Up and Go test were performed. Postoperative use of analgesic drugs was recorded. Knee Society Score (KSS), Oxford Knee Score and Knee Injury and Osteoarthritis Outcome Score (KOOS) were completed at preoperative and 6 weeks post op.
Results
Preliminary results of 32 participants convey the positive outcomes after total knee replacement demonstrated by the improvement in Oxford Knee Score and Knee Osteoarthritis Outcome score. There are marked improvements in the 2-minute walk tests at the six week time-point. At day one post-operative only 5 participants were unable to walk. Patient-controlled analgesia was used on 5 occasions on day one, 2 of which continued on day two. Sedation scores were recorded in six participants on day one and 2 on day two. Nausea was reported in 5 cases on day one and 9 on day two. Urinary catheter was needed in 5 cases on day one.
Importantly the study remains blinded, therefore an analysis of the three study arms is not available and is therefore currently difficult to report on the statistical significance. There will be further assessment of the efficacy of analgesia using VAS pain scores, analgesia consumption and side effects collected preoperatively, 0–24hrs and 24–48 hours postoperatively between the three randomized groups. The assessment of functional outcomes will be measured between the three groups by comparing the ability to mobilize the first 4 hrs after surgery, maximal flexion and extension, two minute walk test and timed up-and-go preoperatively, on postoperative day 1 and 2 and 6 weeks.
Conclusion
Results from the study will provide important information for the management of TKA in the hospital setting. We anticipate completion of all 45 surgeries in the next 2 months. The Blinding codes with be broken thereafter and full data analysis performed.
The comparison of the three commonly used analgesic techniques and mobilization outcomes will allow enhanced management of patient's post-operative pain with earlier discharge from hospital an lower complication rates.
