Overview

This prospective observational study aims to determine the incidence and clinical impact of rebound pain after peripheral nerve blocks in patients undergoing total knee arthroplasty. Rebound pain is defined as a sudden, severe pain (NRS ≥7) emerging after block resolution. Primary outcome is the incidence of rebound pain; secondary outcomes include pain severity, rescue analgesia use, nausea, vomiting, sleep quality, and patient satisfaction.

Eligibility

Inclusion Criteria:

• Age between 18 and 70 years
• ASA physical status I to III
• Scheduled for elective unilateral total knee arthroplasty under spinal anesthesia
• Peripheral nerve block (PNB) planned as part of multimodal analgesia
• Ability to understand and provide written informed consent
• Willingness and ability to complete the postoperative pain diary

Exclusion Criteria:

• Known allergy or hypersensitivity to local anesthetics
• Contraindication to regional anesthesia
• ASA physical status IV or higher
• Neurological or psychiatric disorders interfering with study participation or pain reporting
• Use of anticoagulants or presence of coagulopathy
• Use of medications that may alter pain perception or rebound pain response
• Local infection at the block site
• Emergency surgeries
• Inability or unwillingness to complete the postoperative pain diary or follow-up