Total knee arthroplasty (TKA) is a common and effective surgical intervention for end-stage knee osteoarthritis [1]. Yet, postoperative pain remains a significant challenge affecting recovery, opioid consumption, and overall patient satisfaction [2]. Traditionally, multimodal analgesia strategies incorporating regional anesthesia techniques, such as femoral nerve block (FNB) and adductor canal block (ACB), have been employed to mitigate pain while preserving motor function [3]. However, these techniques often fail to control posterior knee pain, necessitating alternative approaches sufficiently [4].

The infiltration between the popliteal artery and the capsule of the knee (iPACK) block has emerged as a promising strategy to target posterior knee pain by selectively anesthetizing the terminal branches of the sciatic nerve without inducing motor blockade [5]. Recent studies suggest that incorporating the iPACK block into multimodal pain management regimens for TKA can significantly reduce postoperative pain scores, opioid consumption, and systemic inflammation, as reflected by biomarkers such as the neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) [6].

Systemic inflammatory responses following TKA contribute to postoperative morbidity and delayed recovery. The NLR and PLR are widely recognized as markers of surgical stress and systemic inflammation, providing insight into the inflammatory cascade triggered by surgical trauma [7]. The ability of regional anesthetic techniques, such as the iPACK block, to modulate these inflammatory markers remains an area of growing research interest. Prior evidence suggests that patients receiving an iPACK block experience lower inflammatory marker levels, leading to improved functional outcomes and reduced stress responses [8].

Despite these promising findings, the effectiveness of the iPACK block in reducing both postoperative inflammatory responses and opioid consumption in TKA remains underexplored. This randomized controlled trial (RCT) aims to evaluate the impact of the iPACK block with 0.2 % ropivacaine on postoperative NLR levels, pain scores, and opioid requirements compared to a control (sham) group in patients undergoing TKA under spinal anesthesia.