Abstract
INTRODUCTION: After primary total knee arthroplasty (TKA), local periarticular infiltration anaesthesia (LIA) is a fast and safe method for postoperative pain control. Moreover, ultrasound-guided regional anaesthesia (USRA) with femoral and popliteal block is a standard procedure in perioperative care. Two analgesic regimens for TKA-LIA versus URSA with dexmedetomidine-were compared as an additive to ropivacaine. We hypothesised that the use of URSA provides a superior opioid sparing effect for TKA compared with LIA. METHODS: Fifty patients (planned 188 participants; safety analysis was performed after examining the first 50 participants) were randomised. These patients received LIA into the knee capsule during surgery with 60 ml of ropivacaine 0.5% and 1 ml of dexmedetomidine (100 µg ml(-1)) or two single-shot URSA blocks (femoral and popliteal block) before surgery with 15 ml of ropivacaine 0.5% and 0.5 ml of dexmedetomidine for each block. Postoperative opioid consumption in the first 48 h, pain assessment and complications were analysed. RESULTS: In the safety analysis, there was a significantly higher need for opioids in the LIA group, with a median oral morphine equivalent of 42.0 [interquartile range (IQR) 23.5-57.0] mg versus 27.0 [IQR 0.0-33.5] mg (P = 0.022). Due to this finding, the study was terminated for ethical considerations according to the protocol. CONCLUSION: This is the first study presenting data on LIA application in combination with dexmedetomidine. A superior opioid-sparing effect of URSA was observed when compared with LIA in TKA when dexmedetomidine is added to local anaesthetics. Also, a longer lasting opioid-sparing effect in the LIA group was observed when compared with the recently published literature; this difference could be attributed to the addition of dexmedetomidine. Therefore, multimodal analgesia regimens could be further improved when LIA or USRA techniques are combined with dexmedetomidine.