Combined femoral and popliteal nerve block is superior to local periarticular infiltration anaesthesia for postoperative pain control after total knee arthroplasty.

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) 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.