Hip replacement surgery is one of the most commonly performed surgical procedures in France, with approximately 150,000 procedures per year. Postoperative recovery has significantly improved in recent years, enabling faster rehabilitation. Although generally considered moderately painful, hip replacement surgery can, in some difficult-to-predict cases, lead to severe postoperative pain, requiring high doses of morphine, which may cause side effects and delay recovery. In other surgical procedures, regional anesthesia (nerve blocks) has been successfully used for pain relief. However, its effectiveness after hip replacement surgery has not yet been fully proven. A recent regional anesthesia technique-the Supra-Inguinal Fascia Iliaca Block (SIFIB)-which numbs a significant portion of the nerves around the hip, has recently been developed. When performed in all patients undergoing hip arthroplasty, the benefit of this technique could not be demonstrated. In addition, this technique may lead to transcient muscle blockade, wich also can delay recovery. In order to limit the use of nerve blocks to painful patients, we designed this study where the nerve block is performed only in patients experiencing significant paint after surgery. In conclusion, this study aims to assess the benefits of performing a rescue SIFIB in the recovery room for patients who experience significant postoperative pain after hip replacement surgery. The evaluation will focus on pain relief and ability to walk. No new treatment is being tested. The technique uses a commonly administered local anesthetic to numb the nerves.