Deep Subgluteal Block vs PENG Combined With LFCN Block for Analgesia After Hip Arthroplasty

This randomized, prospective, double-blind study is designed to evaluate and compare the postoperative analgesic efficacy of two different ultrasound-guided regional anesthesia techniques in patients undergoing elective hip arthroplasty under general anesthesia. Following institutional ethical approval and written informed consent, a total of 60 patients will be randomly allocated into two equal groups (n=30 per group): Group DSG (Deep Subgluteal Block) and Group PENG+LFCN (Pericapsular Nerve Group block combined with Lateral Femoral Cutaneous Nerve block).

To optimize methodological quality, minimize bias, and maintain a strict double-blind design, both total local anesthetic volume (30 mL) and total active drug dose (75 mg bupivacaine) are perfectly standardized between the groups. All regional blocks will be performed by an experienced anesthesiologist using a high-frequency ultrasound transducer under sterile conditions after surgery is completed but before patient emergence/extubation.

In Group DSG (n=30), patients will receive a total of 30 mL of 0.25% bupivacaine (15 mL administered beneath the gluteus minimus muscle and 15 mL beneath the gluteus medius muscle). No saline will be added to this group.

In Group PENG+LFCN (n=30), patients will receive a total injection volume of 30 mL divided into two separate targets. First, the PENG block will be performed with 20 mL of 0.25% bupivacaine. Second, the LFCN block will be performed using a 10 mL volume consisting of 5 mL of 0.25% bupivacaine diluted with 5 mL of normal saline (0.9% NaCl), resulting in a final local anesthetic concentration of 0.125% bupivacaine at the LFCN site.

Following block administration, a standard general anesthesia protocol will be applied. Postoperative patient-controlled analgesia (PCA) with intravenous fentanyl (10 mcg/mL solution, 10 mcg bolus, 10-minute lockout time, no basal infusion) will be initiated in the post-anesthesia care unit (PACU). Multi-modal analgesia will be supplemented with scheduled oral/IV ibuprofen (400 mg every 8 hours) and tramadol administered 30 minutes before the end of surgery.

Postoperative pain assessments will be performed by a blinded independent investigator at 0 (PACU), 2, 4, 8, 16, and 24 hours using the Numerical Rating Scale (NRS) both at rest and during movement. In case of severe pain (NRS >= 4), intravenous meperidine (0.5 mg/kg) will be administered as rescue analgesia. Cumulative opioid consumption, quadriceps motor strength (evaluated via the Oxford Muscle Strength Scale), and opioid-related adverse effects (such as postoperative nausea, vomiting, or pruritus) will be comprehensively monitored and recorded for the first 24 hours.

Inclusion criteria

• Patients scheduled for elective total or partial hip arthroplasty under general anesthesia
• American Society of Anesthesiologists (ASA) physical status I-III
• Aged between 18 and 80 years
• Able to understand the study procedures, give voluntary written informed consent, and operate a patient-controlled analgesia (PCA) device

Exclusion criteria

• Patient refusal or inability to provide informed consent
• Pre-existing peripheral neuropathy, cognitive impairment, or psychiatric disorders
• History of significant severe renal or hepatic failure
• Allergy or hypersensitivity to amide-type local anesthetics or opioids
• Infection, severe anatomic distortion, or previous surgery at the proposed block injection sites
• History of substance abuse or chronic opioid use (defined as daily opioid use for > 3 months prior to surgery)