Postoperative analgesic effects of intra-articular bupivacaine and morphine after arthroscopic cruciate ligament surgery

Intra-articular administration of local anaesthetics such as bupivacaine can produce short-term postoperative analgesia in patients undergoing diagnostic arthroscopy or arthroscopic meniscectomy. A peripheral anti-nociceptive effect may also be induced by the administration of intra-articular opiates interacting with local opioid receptors in inflamed peripheral tissue. In the present study we aimed to study the analgesic effects of intraarticularly given bupivacaine and morphine sulphate (as well as the combination of both drugs) on postoperative pain. In a prospective, randomized, double-blind manner 40 patients received one of the following: (a) morphine (1 mg in 20 ml NaCl), (b) bupivacaine (20 ml, 0.375%), (c) combination of both or (d) saline (20 ml, control group) intra-articularly at the end of arthroscopic anterior cruciate ligament (ACL) reconstruction. The postoperative pain was assessed via a visual analogue scale (VAS) during the first 48 h after surgery, and supplemental analgesic requirements were noted. All comparisons were made versus the control group receiving saline. The pain scores were significantly lower in the morphine group at 24 and 48 h, and in the bupivacaine group at 2, 4 and 6 h after surgery. In the group that received a combination of both bupivacaine and morphine, the pain scores were significantly reduced throughout the whole postoperative observation period. No side-effects or complications from therapy were seen in any of the groups. The conclusion of this study is that intra-articular morphine is effective in the postoperative period after arthroscopic ACL reconstruction. The combination of bupivacaine and morphine was the most effective postoperative analgesic regimen and resulted in significant analgesia throughout the whole 48-h period following surgery. Patients receiving the combination of bupivacaine and morphine had a significantly shorter hospital stay than the control group.