Although multimodal pain management including periarticular multidrug injection can provide excellent pain relief in the early postoperative period after total knee arthroplasty (TKA), rebounding pain remains an important challenge. A randomized, double-blind, placebo-controlled trial was performed to investigate the efficacy of adding intravenous acetaminophen to multimodal pain management for TKA.
We enrolled 67 patients scheduled for unilateral TKA. Patients were randomly assigned to receive either 1000 mg of intravenous acetaminophen at 6-hour intervals or normal saline at the same intervals. All patients were treated with intraoperative periarticular multidrug injection and intravenous and oral nonsteroidal anti-inflammatory drugs. The primary outcome was the postoperative 100-mm visual analog pain scale at the time of administration of study drugs.
In the intention-to-treat analysis, the pain score was significantly better in the intravenous acetaminophen group than the placebo group at 17:00 one day after TKA (15.3 ± 17.0 mm vs 26.8 ± 19.0 mm; P = .013). There were no significant differences in terms of the rate of complications between groups.
Even in the setting of multimodal pain management including periarticular multidrug injection, intravenous acetaminophen provided better pain relief for patients undergoing unilateral TKA.