82 patients scheduled for total knee arthroplasty were randomized to postoperative analgesia with either a preoperative motor-sparing block (MSB), which targeted the adductor canal and lateral femoral cutaneous nerves via a posterior injection under ultrasound or to intraoperative periarticular injection (PAI) analgesia. Patients were assessed for the time until the first request of rescue analgesia, quadriceps strength, and length of stay. Results demonstrated a significantly lower time to first rescue analgesia request in the MSB group compared to the PAI group, while no significant differences were observed in quadriceps strength or length of stay.