105 patients scheduled for total knee arthroplasty were randomized to superficial periarticular injection performed either early in the procedure (after exposure of the fascial layer) or late in the procedure (following implant cementation). The primary outcome of interest was pain at rest score from immediately after surgery to 48 hours postoperatively. Results on the primary outcome demonstrated significantly lower pain scores immediately after surgery in the early PAI group compared to the late PAI group, with no significant difference between groups from 3 hours to 48 hours. Secondary outcome measures of rescue analgesia consumption over the first 3 days postoperatively, range of motion over the first 7 days postoperatively, and incidence of adverse events did not significantly differ between groups.