A comparison of the analgesic efficacy of local infiltration analgesia vs. intrathecal morphine after total knee replacement: A randomised controlled trial

53 patients scheduled for a unilateral total knee replacement under spinal anesthesia were randomized to receive local infiltration analgesia with levobupivacaine and adrenaline, or intrathecal preservative-free morphine in conjunction with the spinal anesthesia. The primary outcomes of interest were pain scores at 24 hours at rest and on passive flexion to 30deg, measured on a Visual Analog Scale (VAS). Secondary outcomes of interest included VAS pain scores at rest and during motion, morphine consumption, maximum active flexion, maximum active straight leg raise, the incidence of opioid-related adverse events, and patient satisfaction with analgesia and the overall experience. Follow up was performed up to 48 hours post-operation. Results revealed significantly favourable VAS pain at rest and during passive flexion in the LIA group compared to the morphine group at 24 hours post-operation. Additionally, pain scores during movement were significantly in favour of the LIA group at both 24 and 48 hours. There were no significant differences in maximum active flexion or maximum active straight leg raise, morphine consumption, or patient satisfaction with analgesia. The incidence of nausea and pruritus were significantly lower in the LIA group. Patient satisfaction with the overall procedure was significantly more favourable in the LIA group.