In recent years, the use of regional anesthesia techniques as part of multimodal analgesia strategies to maximize pain control in patients has reduced opioid requirements and promoted early mobility and rehabilitation in the perioperative period. Regional anesthesia has benefits, mainly peripheral nerve blocks (PNB), muscle relaxation, and postoperative analgesia, thus allowing for control of postoperative pain and early discharge from the hospital. In addition, using PNB techniques provides:

Hemodynamic stability. Reduced need for a post-anesthetic care unit (PACU). Reduced unplanned hospitalization for pain control. Less airway management. Reduced incidence of opioid-related adverse events. Greater patient satisfaction

The main feature of rebound pain is that it is severe pain, within 8-24 hours after PNB. It usually remains severe for 2-6 hours, but the subsequent pain trajectory is consistent with the recovery process expected at surgical intervention. Therefore, rebound pain is temporary and different from persistent post-surgical pain (PPSP).

Rebound pain often occurs at night. However, this is probably related to the 8 to 12-hour duration of most single-injection PNBs and the completion of most elective surgeries during daylight hours.

This study aims to reveal the rebound pain profile, determine the risk factors, and contribute to developing strategies that can prevent rebound pain.

Inclusion Criteria:

• Patients aged >18 years who underwent orthopedic surgery with the peripheral nerve block

Exclusion Criteria:

• Patients who did not want to participate in the study
• dementia
• severe psychiatric or cognitive dysfunction
• coagulopathy
• neuropathic disorder
• local anesthetic allergy
• serious heart-lung disease
• chronic opioid use

Patients aged >18 years who underwent orthopedic surgery with the peripheral nerve block will be included in the study.