Adequate pain management is crucial for timely discharge of patients after total knee arthroplasty (TKA) surgeries. Regional anaesthesia, particularly peripheral nerve blocks, has become increasingly important in optimizing postoperative pain management and expediting discharge.At present, various techniques can be used to relieve postoperative pain, including epidural anaesthesia, femoral nerve block (FNB), adductor canal block (ACB), and local infiltration analgesia (LIA). A recent network analysis suggests the consideration of a single injection femoral nerve block combined with a sciatic nerve block, or local infiltration analgesia for knee surgeries. [1]

While femoral nerve blocks (FNB) have been associated with less pain and reduced analgesic consumption, there is an increased risk of motor weakness of the quadriceps muscles, and accidental falls as compared to a placebo. [2,3] Besides short-term effects, a decreased quadriceps strength has also been observed six weeks after ACL reconstruction in patients who had received FNB. [4] Recently, ACB has emerged as an alternative to FNB, with the advantage of sparing the motor nerve supply to most of the quadriceps muscle and may lead to a reduction in falls after surgery. [5] Several studies have reported similar pain relief and a reduction in the loss of quadriceps motor strength in favor of ACB compared to FNB. [6,7,8] However, other studies have reported more pain after ACB, or similar quadriceps muscle function between both groups. [9,10,11]

 Readiness for discharge is an important patient outcome, including various factors such as pain management, associated side effects, mobility, vital parameters, and the presence of any surgical complications such as bleeding [18]. Adductor canal block with higher volume or concentrations may affect quadriceps strength, while higher concentrations may have more analgesic efficacy.[19] Data are limited on comparison of different concentrations of local anaesthetic agents (LA) for adductor canal block (ACB). We hypothesized that 0.5% ropivacaine would provide superior analgesic efficacy to 0.2% ropivacaine. Hence, we plan to compare the impact of two different concentrations of ropivacaine for ACB with regards to its analgesic efficacy and quadriceps muscle strength in patients undergoing total knee arthroplasties.