Tranexamic acid in local infiltration analgesia cocktail for pain and swelling after total knee arthroplasty: a randomized controlled trial

BACKGROUND: Peri-articular local infiltration analgesia (LIA) is a cornerstone technique in multimodal pain management during the peri-operative period of total knee arthroplasty (TKA). Tranexamic acid (TXA), an antifibrinolytic agent, is widely used to reduce post-operative bleeding in TKA. However, no study has systematically evaluated the impact of adding TXA as an adjuvant to the LIA cocktail on post-operative pain and swelling following TKA. The purpose of this study is to investigate the efficacy and convenience of incorporating TXA into the analgesic cocktail for alleviating pain and swelling after TKA. METHODS: In this double-blind, randomized controlled trial, 100 patients undergoing TKA were allocated to either a TXA group or a control group. The TXA group received LIA with an analgesic cocktail consisting of ropivacaine, epinephrine, dexamethasone, and TXA, while the control group received an identical cocktail without TXA. The primary outcome was the pain score at rest at 24 h post-operatively. Secondary outcomes comprised pain scores at other time points, post-operative morphine consumption for rescue analgesia, time to first rescue analgesia, knee swelling rate, decrease in hemoglobin level, range of motion (ROM) of the knee, and incidence of complications. RESULTS: The TXA group demonstrated significantly lower VAS pain scores at rest at 24 h post-operatively (3.5 ± 0.6 vs. 4.0 ± 0.7, p = 0.001, and a markedly smaller decline in hemoglobin levels (26.2 ± 7.1 g/L vs. 33.5 ± 7.5 g/L, p < 0.001. Knee swelling rates were also significantly reduced in the TXA group. However, the absolute difference in VAS scores did not exceed the reported minimal clinically important difference (MCID) for pain in TKA (typically 1.0 point). No significant differences were observed between the two groups in post-operative morphine consumption, time to first rescue analgesia, knee ROM, or complication rates. CONCLUSION: The addition of TXA to a commonly used LIA cocktail led to a statistically significant reduction in early post-operative pain and swelling, along with decreased blood loss, which may offer added convenience by streamlining the workflow. However, the reduction in pain did not meet the MCID, indicating limited clinical relevance in terms of analgesia. Future studies are needed to optimize the analgesic efficacy of TXA-containing cocktails. TRIAL REGISTRATION: Chinese Clinical Trial Registry, ChiCTR2400086985. Registered 16 July 2024.