Single-shot Intraoperative Local Anaesthetic Infiltration Does Not Reduce Morphine Consumption After Total Hip Arthroplasty: a Double-blinded Placebo-controlled Randomized Study

Background: The infiltration of local anaesthetic (LA), ketorolac, and epinephrine has been suggested to be effective for analgesia after total hip arthroplasty (THA). The part of action of each component of the mixture remains unclear. We investigated the contribution of infiltration of ropivacaine alone on the morphine consumption during the first 24 h after surgery.

Methods: Sixty patients undergoing primary THA were included in this prospective randomized double-blinded placebo-controlled trial, after IRB approval and informed consent. Surgical and general anaesthetic management were standardized. At the end of surgery, 80 ml of ropivacaine 0.2% (160 mg) or saline was infiltrated. The primary endpoint was morphine consumption 24 h after surgery. The secondary endpoints were: visual analogue scale scores and opioid side-effects at H2, H4, H8, H12, H24, D1, D2, D3, D4, D5, rehabilitation programme progress, chronic pain level, analgesic consumption, and surgical result at 3 months and 1 yr after surgery. The observation period was 1 yr.

Results: Groups were similar for patient characteristic and perioperative characteristics. The ropivacaine wound infiltration did not reduce morphine consumption at 24 h [median (25th and 75th inter-quartile) 27 (17-37) mg in the ropivacaine group vs 24 (18-34) mg in the placebo group, P=0.51] or its side-effects. No effect was found on rehabilitation progress or chronic pain after 3 months or 1 yr, but these were not the main endpoints of the study.

Conclusions: Ropivacaine infiltration alone did not reduce morphine consumption at 24 h after operation nor did it improve postoperative rehabilitation.