Intra-articular injection of warmed lidocaine improves intraoperative anaesthetic and postoperative analgesic conditions.

BACKGROUND Although local anaesthesia for knee arthroscopy is a well-documented procedure, arthroscopy under local anaesthesia is often interrupted because of intolerable discomfort and pain. Warming local anaesthetic solutions may increase its anaesthetic effect. We tested whether intra-articular injection of warmed lidocaine solution could improve intraoperative anaesthetic and postoperative analgesic conditions. METHODS Patients in the warmed group received 20 ml warmed (40 degrees C) lidocaine 1% intra-articularly 20 min before surgery. The patients in the control group received 20 ml room-temperature (25 degrees C) lidocaine 1% intra-articularly 20 min before surgery. During surgery, the patients reported pain on a visual analogue scale (VAS). RESULTS The median VAS pain score was 1.5 (range, 0.0-3.0) in the warmed lidocaine group and 5.0 (4.0-8.0) in the control group (P<0.001). The median intra- and postoperative analgesic requirements in the control group were significantly greater than that in the warmed group. CONCLUSION Warmed lidocaine injected intra-articularly provides improved intraoperative anaesthetic and postoperative analgesic conditions for patients undergoing knee arthroscopy.