Title: A comparison of the analgesic efficacy of local infiltration analgesia versus intrathecal morphine for total knee replacement; a randomised controlled trial.

Investigating team: Denise McCarthy, John McNamara, John Galbraith, Frank Loughnane, George Shorten, Gabriella Iohom

Background: Methods of postoperative analgesia for orthopedic surgery include intrathecal opiates, epidural analgesia, intravenous patient controlled opioid analgesia, and peripheral nerve blocks. These techniques are associated with significant adverse effects and some require a high level of expertise to perform. Local anaesthetic infiltration has been described as an option for postoperative pain management in patients following total knee arthroplasty.

Objective: To compare local anesthetic infiltration and intrathecal morphine in terms of postoperative analgesia for patients undergoing unilateral total knee arthroplasty.

Results: VAS scores for pain at 24 hours were less in the infiltration group compared with those in the standard group both at rest [5.0 (0.0, 36.5) median (IQR) Vs 31.0 (3.0, 67.3), p=0.029] and on movement [41.0 (18.0, 57.5) Vs 58.5 (28.3, 80.8), p=0.044]. At 48 hours postoperatively, VAS scores in the infiltration group were less on movement compared with those in the standard group [26.0 (13.5, 37.0) Vs 40.0 (19.5, 56.0), p=0.035].

When compared with intrathecal morphine 0.3 mg, periarticular local anesthetic infiltration is associated with superior analgesia at 24 and 48 hours after total knee arthroplasty.

Current status: In press European Journal of Anaesthesiology