69 patients scheduled for primary shoulder arthroplasty under general anaesthesia were randomized to postoperative analgesia through either local infiltration analgesia (LIA) or a continuous interscalene brachial plexus block (ISBPB). The primary outcome was cumulative opioid consumption over the first 24 postoperative hours and pain scores were assessed as a secondary outcome. Findings demonstrated significantly greater opioid consumption over the first 24 hours postoperatively in the LIA group compared to the ISBPB group. Differences in opioid consumption of postoperative days 1, 2 and 3 were not significant. Pain scores were also significantly higher in the LIA group compared to the ISBPB group over the first 8 hours postoperatively; differences thereafter were not statistically significant.