Effects of intravenous lidocaine in total knee joint arthroplasty: An interim analysis

Abstract

Introduction: Lidocaine, a widely-used local anaesthetic, is proved effective in reducing postoperative pain when administered intravenously in gastrointestinal surgeries. A double-blind randomised controlled trial was conducted to determine the effect of intravenous lidocaine in total knee arthroplasty (TKR). The primary outcome was pain. Secondary outcomes included opioid consumption, range of movement, walking distance, local anaesthetic systemic toxicity (LAST), constipation, and functioning score. Methods: Thirty patients having unilateral TKR were randomly assigned to a bolus of intravenous lidocaine (2 mg/ kg) or placebo before skin incision. All patients received standardised spinal anaesthesia, local infiltration analgesia, and postoperative analgesic regimen. Pain during movement and rest were measured by numerical rating score (NRS). Cumulative opioid consumption, active and passive range of movement of the knee, walking distance, occurrence of LAST, constipation, and Modified Barthel Index were measured until discharge. Mann-Whitney U test was used for numerical values and Chi-square or Fisher’s exact test categorical data. Results: Statistically significant reduction in NRS was observed in the treatment group at 1 day after surgery (p=0.025; median [95% confidence interval] of 0.69 [-0.24-1.63] vs 2.5 [1.33-3.67]). Numerical rating score was also lower in the treatment group at 2 days (p=0.156; 1.46 [-0.09-3.01] vs 3 [1.34-4.66]) and 3 days (p=0.768; 1.2 [-1.49-3.89] vs 1.8 [0.23-3.37]) after surgery. Lower cumulative opioid consumption (p=0.909; 1.5 [0.05-2.95] vs 1.69 [0.03-3.35]) was noted as well. Postoperative range of movement, walking distance, Modified Barthel Index, and incidence of constipation was comparable. No LAST was recorded. Conclusion: Pre-emptive bolus of intravenous lidocaine may reduce postoperative pain without risk of LAST.