Pursuing an Optimal Regional Analgesia Strategy for Total Knee Arthroplasty: A Double-Blind Randomized Controlled Study of Femoral Triangle, Adductor Canal, and Dual Subsartorial Blocks (FAD Trial).

Background Total knee arthroplasty (TKA) is often associated with intense postoperative pain, which can delay mobilization and hinder recovery. While motor-sparing blocks such as the femoral triangle block (FTB) and adductor canal block (ACB) are commonly used, both offer incomplete analgesic coverage. To overcome these limitations, the dual subsartorial block (DSB) was introduced as a procedure-specific, motor-sparing technique that combines and modifies FTB and ACB into a dual-injection approach for enhanced efficacy. Objective The objective of this study is to compare the analgesic efficacy, motor-sparing effect, opioid-sparing potential, and patient satisfaction among three regional analgesia (RA) techniques, FTB, ACB, and DSB, in patients undergoing TKA. Methods This prospective, double-blind, monocentric trial enrolled 120 patients undergoing unilateral primary TKA, randomized equally into FTB, ACB, or DSB groups (n = 40 each). All patients received standardized spinal anesthesia followed by the assigned ultrasound-guided block. The primary outcome was postoperative quadriceps strength. Secondary outcomes included visual analog scale (VAS) pain scores, rescue opioid use, pain location mapping, patient satisfaction, and block duration. Results Quadriceps strength was preserved in all groups. DSB showed significantly better static and dynamic pain control (p < 0.001), with zero opioid use compared to minimal use in FTB and highest use in ACB. Pain mapping revealed incomplete coverage with ACB, particularly at upper incision sites. DSB provided the longest block duration (>24 hours) and the highest satisfaction scores. Conclusions DSB, which strategically integrates and modifies FTB and ACB, offers superior, comprehensive, and motor-sparing analgesia. Its enhanced anatomical precision and functional benefits suggest that DSB can be considered a reliable, procedure-specific RA technique with a strong potential to improve outcomes in modern TKA care pathways.