Abstract
Background
Pain control following knee replacement (TKR) surgery is often poor. Moderate to severe pain is often reported in the first 48 hours following surgery requiring opiate analgesia. The Local Infiltration Anaesthetic (LIA) technique has been described as a method to reduce post operative pain. In this study we report on our experience using LIA in addition to the PainKwell system (Peak Medical) of continuous infusion intra-articularly, of 0.25% bupivacaine at 4–5 mls/hour for 48 hours post surgery. The PainKwell catheter is placed in the knee joint during surgery.
Methods
Between the June 2012 and Sep 2012, 62 patients undergoing primary TKR were prospectively followed up. All patients studied had spinal anaesthesia (SA) with diamorphine. Group 1. GA. No LIA and no PainKwell. 20 patients. Group 2. SA plus LIA plus PainKwell for 48 hours post operatively with catheter placed anteriorly under the patella. 21 patients. Group 3. SA plus LIA plus PainKwell for 48 hours post operatively with catheter placed posteriorly in the knee joint. 21 patients.
Results
The patients without LIA or PainKwell required more morphine in the first 12 hours postoperative period than the other groups. Seventy percent (n=14) of these group 1 patients required 10mg morphine following TKR compared to only 2% (n=1) of patients requiring 10mg of morphine when LIA and PainKwell as used. The increased morphine requirement continued for 48 hours postoperatively in group 1, whereas none of the patients in groups 2 or 3 required morphine after 36 hours. Fewer patients suffered from nausea and vomiting or urinary retention in the group with LIA and PainKwell.
