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Background and Aims Postoperative pain management following total knee arthroplasty (TKA) is critical, particularly for the posterior knee capsule. The IPACK (infiltration between the popliteal artery and the capsule of the knee) block and the popliteal plexus block (PPB) are increasingly used as motor-sparing alternatives to sciatic or tibial nerve blocks for postoperative analgesia. We conducted a double-blind, randomized controlled trial to evaluate whether PPB offers superior motor preservation compared to IPACK, focusing on ankle dorsiflexion and plantarflexion strength.Methods Eighty-seven patients undergoing TKA were randomized to receive either IPACK or PPB with 15 mL of 0.25% levobupivacaine. All patients received an adductor canal block with 10 mL of 0.25% levobupivacaine. The primary outcome was dorsiflexion strength at 6 hours post-block, expressed as a percentage of the preoperative baseline. Secondary outcomes included plantarflexion strength, time to meet discharge criteria (>90° knee flexion, adequate pain control, and ambulation), pain scores, supplemental analgesic use, knee ROM, quadriceps function, and anesthesia-related complications.Results Dorsiflexion strength at 6 hours post-block was significantly higher in the PPB group (78% ± 17%) than in the IPACK group (61% ± 17%) (difference: 17%; 95% CI: 7–21%; p < 0.001). A similar difference was observed at 24 hours (PPB: 94% ± 17% vs. IPACK: 81% ± 18%; difference: 13%; 95% CI: 8–23%; p < 0.001). Plantarflexion strength also differed significantly between groups (6 hours: 83% vs. 68%; 24 hours: 98% vs. 90%). No significant differences were observed in other secondary outcomes.Conclusions PPB demonstrated superior preservation of dorsiflexion and plantarflexion strength at 6 and 24 hours postoperatively compared to IPACK. However, this motor-sparing advantage did not translate into improved outcomes such as pain control or discharge readiness. Nevertheless, PPB may offer benefits for early rehabilitation by minimizing motor nerve blockade.