A Comparative Analysis of Bupivacaine Concentrations in Adductor Canal Block for Pain Management Post-unilateral Knee Arthroplasty.

Background: The adductor canal block (ACB) is a widely recognized intervention for post-surgical pain management following total knee arthroplasty (TKA). Objectives: In this study, we evaluated the analgesic efficacy and functional outcomes of ACB between bupivacaine at concentrations of 0.5% and 0.25% in participants who underwent primary unilateral TKA. Methods: In this randomized controlled trial, we monitored participants who had undergone TKA surgery. They were randomly assigned to receive postoperative ACB with either 0.5% bupivacaine (22 patients) or 0.25% bupivacaine (22 patients). Data were collected at various time points following the intervention, including quadriceps muscle tone assessed by the Manual Muscle Contraction Test (MMT), pain levels measured using the Visual Analog Scale (VAS) pain scores, analgesic consumption, and patient satisfaction with pain control. Results: There was no significant difference in pain intensity between the two groups three hours after surgery (P = 0.55). However, the group receiving 0.5% bupivacaine showed a statistically significant trend toward lower VAS scores at 6, 12, and 24 hours post-operation compared to the 0.25% bupivacaine group (P = 0.02, P < 0.005, and P = 0.002, respectively). Patients' satisfaction with postoperative pain management and quadriceps muscle strength did not differ significantly between the two groups. Similarly, opioid consumption at 3, 6, and 24 hours post-surgery showed no significant difference (P = 0.052, P = 0.43). However, opioid consumption was notably higher in the 0.25% bupivacaine group 12 hours after surgery compared to the 0.5% bupivacaine group (P = 0.002). Conclusions: This study demonstrates that a higher dose of bupivacaine plays a crucial role in effectively reducing postoperative pain and minimizing the need for narcotic consumption.