Safety and Efficacy of Dexamethasone Versus Dexmedetomidine as Adjuvants in PENG Block in Hip Surgeries for Postoperative Pain Management

This study evaluates and compares the analgesic efficacy and safety of adding dexamethasone versus dexmedetomidine to bupivacaine in an ultrasound-guided pericapsular nerve group (PENG) block combined with a lateral femoral cutaneous nerve (LFCN) block in patients undergoing elective total hip replacement under spinal anesthesia. Total hip replacement is associated with substantial acute postoperative pain. The PENG block targets sensory articular branches supplying the hip while preserving quadriceps muscle strength, facilitating early postoperative ambulation. Supplementation with an LFCN block expands sensory coverage to the lateral surgical incision. Adding perineural adjuvants, such as dexamethasone or dexmedetomidine, to local anesthetics may prolong sensory block duration and reduce opioid requirements. A total of 90 adult participants aged 18 to 60 years will be randomly assigned to one of three equal groups (30 patients each): * Group C (Control): Receives a PENG block with 20 mL of plain bupivacaine 0.25%. * Group DX: Receives a PENG block with 20 mL of bupivacaine 0.25% combined with dexamethasone 4 mg. * Group DM: Receives a PENG block with 20 mL of bupivacaine 0.25% combined with dexmedetomidine 1 µg/kg. All participants across all groups will receive an LFCN block with 5 mL of plain bupivacaine 0.25% without adjuvants. The primary outcome is the time to the first request for rescue analgesia (duration of postoperative analgesia). Secondary outcomes include total morphine consumption over the first 24 hours, pain intensity measured using the Visual Analogue Scale (VAS), intraoperative and postoperative hemodynamic stability, sedation levels, quality of recovery assessed at 24 hours via the Quality of Recovery-15 (QoR-15) questionnaire, and the incidence of any adverse effects or block-related complications.

Inclusion Criteria: * Patients aged 18 to 60 years. * American Society of Anesthesiologists (ASA) physical status class I or II. * Scheduled for elective unilateral total hip replacement under spinal anesthesia. Exclusion Criteria: * Patient refusal of the peripheral nerve block. * Infection at the site of injection. * Coagulopathy or contraindication to spinal anesthesia. * Known allergy or hypersensitivity to any of the study medications. * Baseline bradycardia or significant cardiac conduction abnormality. * Chronic opioid use or pre-existing chronic pain on regular analgesics. * Patients unable to communicate or reliably express pain scores.