Combined proximal or distal nerve blocks for postoperative analgesia after total knee arthroplasty: a randomised controlled trial

Abstract

Background: Many regional anaesthetic techniques have been proposed to manage pain after total knee arthroplasty, but the best approach is unclear. We compared opioid consumption in the first 48 h between two different regional anaesthesia strategies in patients undergoing total knee arthroplasty.

Methods: In this single-centre, prospective study, we randomly allocated 90 patients to a combination of IPACK (interspace between popliteal artery and capsule of the posterior knee), triangle femoral and obturator nerve blocks (distal group), or a combination of sciatic, femoral, obturator, and lateral femoral cutaneous nerve blocks (proximal group). All patients received an opioid-sparing general anaesthesia regimen. The primary outcome was opioid consumption in the first 48 h. Secondary outcomes included opioid consumption in the first 24 h and verbal rating pain scores in the first 48 h.

Results: There was no difference in median cumulative oral morphine equivalent consumption at 48 h between the distal and the proximal block groups (33 [18-78] mg vs 30 [22-51] mg, respectively; P=0.29). Median oral morphine equivalent consumption at 24 h was higher in the distal group compared with the proximal group (30 [13-59] vs 15 [0-18], respectively; P<0.001). Verbal rating pain scores were lower in the proximal group compared with the distal group on arrival to the postanaesthesia care unit and at 6 and 12 h.

Conclusions: In patients undergoing total knee arthroplasty under total intravenous general anaesthesia with a multimodal analgesia regimen, proximal nerve blocks resulted in improved pain scores in the first 12 h and reduced opioid consumption in the first 24 h when compared with distal nerve blocks. No difference in pain scores or opioid consumption was seen at 48 h.

Clinical trial registration: NCT04499716.

Keywords: femoral nerve block; lateral femoral cutaneous nerve block; multimodal analgesia; obturator nerve block; opioid consumption; opioid-sparing anaesthesia; peripheral nerve blocks; sciatic nerve block; total knee arthroplasty.