The Interspace between the Popliteal Artery and Capsule of the Posterior Knee (iPACK) block, has been recently described and shows promise in providing analgesia to the knee joint. The effect of this block on postoperative rehabilitation is uncertain. This study aims to compare a preoperative iPACK block to a placebo block prior to total knee arthroplasty under spinal anesthesia. The primary outcome measure is verticalization, walking distance, ability to go out of bed, active lifting of the limb, range of motion in the hip joint, bending range of motion, and abduction range of motion. The secondary measure is postoperative pain assessment during rehabilitation.