Abstract: Objective To compare the analgesic efficacy of liposomal bupivacaine with that of a traditional periarticular injection(TPAI)in patients undergoing total knee arthroplasty(TKA). Methods A total of 60 patients(28 males and 32 females, aged 53-83 years, with a mean age of 68.15 years)who were scheduled to undergo unilateral TKA between April and September 2024 were enrolled in this study. The patients were randomly assigned to either the liposomal bupivacaine group or the TPAI group. The primary outcome was pain intensity, which was assessed by the visual analogue scale(VAS)during activity and at rest at 24, 48, and 72 hours postoperatively. Secondary outcomes included the range of motion(ROM)at 72 hours, Western Ontario and McMaster Universities Osteoarthritis Index(WOMAC)score at discharge, the time to first use of patient-controlled analgesia(PCA), time to leg lift and ambulation, incidence of postoperative nausea and bleeding, and frequency of tramadol consumption. Results The resuts showed that the liposomal bupivacaine group had significantly lower pain scores during activity at 24(P=0.04), 48(P=0.02), and 72(P=0.02)hours postoperatively compared to the TPAI group. There were no statistically significant differences between the two groups in pain scores at rest, ROM, WOMAC scores, time to first PCA use, time to leg lift, time to ambulation, incidence of postoperative nausea or bleeding, or frequency of tramadol consumption(P>0.05). Conclusion Liposomal bupivacaine provides superior analgesia during activity compared to the TPAI after total knee arthroplasty(TKA), although it shows no significant advantage for pain at rest or on other secondary outcomes. These findings suggest its potential role in multimodal analgesia strategies for TKA.

Key words: Liposomal bupivacaine, Total knee arthroplasty, Periarticular injection, Multimodal analgesia, Pain management