This randomized, double-blind comparative study evaluates postoperative analgesic efficacy and motor effects of ultrasound-guided para-sartorial compartments (PASC) block versus ultrasound-guided combined femoral-sciatic nerve block in patients undergoing total knee arthroplasty. The primary endpoint is total nalbuphine rescue analgesia consumption in the first 24 postoperative hours. Secondary endpoints include pain scores (NRS), motor function using a modified Bromage scale, block performance characteristics, and complications.