Liposomal Bupivacaine for Adductor Canal Block Combined with IPACK Block in Total Knee Arthroplasty: A Prospective, Double-Blind, Randomized Controlled Trial

Purpose: Patients undergoing total knee arthroplasty (TKA) may experience severe postoperative pain despite preoperative nerve blocks. This study aims to investigate the effect of liposomal bupivacaine (LB) for adductor canal block (ACB) combined with infiltration between the popliteal artery and the posterior knee capsule (iPACK) in TKA. Patients and Methods: This prospective, double-blind, randomized controlled trial was conducted from March 2025 to August 2025 in a Chinese tertiary hospital. 86 patients aged 18– 90 years, classified as the American Society of Anesthesiologists (ASA) Physical Status I–III and undergoing TKA, were randomly assigned to either the liposomal bupivacaine group (Group LB) or ropivacaine group (Group R). All patients underwent ACB combined with iPACK block administered with either LB or ropivacaine preoperatively. The primary outcome was visual analog scale (VAS) at multiple time points under three conditions: at rest, during maximum knee flexion, and during ambulation. Secondary outcomes included opioids consumption, knee range of motion (ROM), quadriceps strength, the Timed Up-and-Go (TUG) test within the first 3 days, as well as the American Knee Society (AKS) score and the Quality of Recovery-15 (QoR-15) score assessed at 2 weeks and 1 month. Results: Demographic and baseline characteristics were comparable between groups (P> 0.05). The VAS scores in Group LB were significantly lower than those in Group R at 24h, 48h, and 72h across all assessment conditions ( P < 0.05). However, these differences did not reach the minimal clinically important difference (MCID). From 48h to 72h, opioids consumption in Group LB was significantly lower than that in Group R ( P < 0.05), but again not clinically significant. No significant differences were observed between groups in other outcomes ( P > 0.05). Conclusion: Liposomal Bupivacaine for adductor canal block combined with IPACK block provided no clinically significant benefit in patients undergoing total knee arthroplasty. Keywords: liposomal bupivacaine, adductor canal block, iPACK block, total knee arthroplasty