Sixty-nine patients undergoing primary TKA were randomized to receive suprainguinal fascia iliaca plane block (SFIPB) with dilute, high-volume bupivacaine/epinephrine (n=35) or surgeon-performed periarticular infiltration (PAI) (n=34). The primary outcome was cumulative opioid (fentanyl) consumption to 48 hours. Secondary outcomes included VAS pain (anterior/posterior; rest/movement), time to first rescue analgesia, quadriceps strength, mobilization time, range of motion (ROM), Time-Up-and-Go (TUG), five-times-sit-to-stand (FTSST), and adverse effects, assessed over 0–48 hours and on postoperative days 1–2. Overall, the results showed lower 24- and 48-hour opioid use with SFIPB, better anterior knee pain scores, improved quadriceps strength, and faster TUG performance, with fewer nausea/vomiting events. These findings suggest SFIPB can reduce opioid needs and related side effects after TKA without compromising motor recovery.