Abstract
Introduction
The peri-operative analgesic management of patients having either Total Knee Replacement (TKR) or Unicompartmental Knee Replacement (UKR) is an area that continues to have prominence, driven in part by the desire to reduce hospital stay, while maintaining high patient satisfaction. This is particularly relevant in the current climate of healthcare cost savings. We evaluated the role of “top up” intra-articular local anaesthetic injection after identifying that an appreciable number of patients in the unit suffered “breakthrough pain” on the first post-op day, when the effects of local analgesia are wearing off.
Method
43 patients, who were scheduled to have a cemented Oxford UKR, were prospectively recruited and randomised. All patients had the same initial anaesthetic regime of general anaesthesia, femoral nerve block and intra-operative intra-articular infiltration of the cocktail. All patients had a 16G multi-holed epidural catheter placed intra-articularly prior to wound closure. Patients had the same operative technique, post operative rehabilitation and rescue analgesia.
An independent observer recorded post-operative pain scores using a visual analogue score (1–10) every 6 hours and any rescue analgesia that was required. On the morning after surgery, 22 patients, (Group I), received 20 mls of 0.5% bupivicaine through the catheter whilst 21 patients, (Group II), had 20 mls of normal saline by the same observer, (who was blinded to the contents of the solution being injected), after which the catheter was removed.
Results
When comparing these two groups there was no statistical difference found in their pain scores on the day of operation. However, patients in Group I had a significantly better pain score initially post top up and then at 6 hours (2.4 (0–8) vs 5.7 (2–9), Mann-Whitney p<0.001). This cohort of patients required less rescue analgesia (22% vs 75%, Mann-Whitney p<0.001). In addition, Group I had statistically significant higher patient satisfaction outcome scores after the infiltration, (p<0.001), with 16 reporting very good satisfaction in comparison to 1 in Group II. There were no complications in either group.
Discussion
Our study has shown that injection of local anaesthesia via an intra-articular catheter does reduce pain scores when compared to placebo. This implies that this technique may have a role in providing optimal pain relief after UKR.
