ORIGINAL ARTICLE: Analgesic efficacy of intracapsular and intra‐articular local anaesthesia for knee arthroplasty

Abstract

The optimal site for wound delivery of local anaesthetic after total knee arthroplasty is undetermined. Sixty patients having total knee arthroplasty received intra-operative infiltration analgesia with ropivacaine 0.2% and were then were randomly assigned to receive either intracapsular or intra-articular catheters with 20 ml ropivacaine 0.5% given at 6 h and again at 24 h, postoperatively. Analgesic efficacy was assessed for 3 h after each injection, using a visual analogue score, where 0 = no pain and 100 = worst pain. There was no statistically significant difference between groups. Maximum pain relief (median (IQR [range])) at rest observed in the 3 h after the 6 and 24 h postoperative injections was 17 (7-31 [0-80]) and 10 (4-27 [0-50]) p = 0.27 for 6-9 h; and 17 (7-33 [0-100]) and 13 (3-25 [0-72]) p = 0.28 for 24-27 h, for intracapsular and intra-articular, respectively. Intracapsular local anaesthetic has similar analgesic efficacy to intra-articular after total knee arthroplasty.