Hip replacement surgery (partial or total hip arthroplasty) is commonly performed in elderly patients and is associated with significant postoperative pain. Effective pain management is critical to support early mobilization, reduce complications, shorten hospital stay, and prevent postoperative delirium.This observational study evaluates the effect of two ultrasound-guided regional analgesia approaches on postoperative pain and recovery quality in patients aged 65 years and older undergoing hip arthroplasty under general anesthesia:

Group 1: Pericapsular Nerve Group (PENG) block + Lateral Femoral Cutaneous Nerve (LFCN) block Group 2: PENG block + Lumbar Erector Spinae Plane (ESP) block Both techniques are applied as part of routine clinical practice at our institution. The primary outcome is quality of recovery assessed by the QoR-15 questionnaire at 24 hours after surgery. Secondary outcomes include postoperative opioid consumption, pain scores (NRS), incidence of postoperative delirium (NU-DESC), nausea and vomiting, and time to mobilization. Patients are also followed up by telephone at postoperative day 7 and day 30 for mortality and morbidity assessment.

Study Design This is a prospective, observational, single-center study conducted at Fatih Sultan Mehmet Training and Research Hospital, Istanbul, Turkey. Patients were allocated to one of two regional analgesia groups based on clinical decision-making by the anesthesia team according to surgical type, patient positioning, and clinician experience, consistent with the routine clinical practice of the institution.

Patient Population Patients aged ≥65 years, ASA physical status I-III, scheduled for elective partial or total hip arthroplasty under general anesthesia were enrolled. Patients with a Mini-Mental State Examination (MMSE) score below 24 were excluded. Written informed consent was obtained the day before surgery.

Anesthesia Protocol All patients received standardized general anesthesia: induction with propofol 2 mg/kg IV, fentanyl 2 mcg/kg IV, and rocuronium 0.6 mg/kg IV; maintenance with sevoflurane 1.5-2% and remifentanil 0.05-0.5 mcg/kg/min infusion, titrated to BIS 40-60. Standard monitoring included ECG, non-invasive blood pressure, SpO2, temperature, and BIS. Normothermia was maintained with active forced-air warming. All patients received paracetamol 1 g IV, tramadol 1 mg/kg IV, and ondansetron 4 mg IV 20 minutes before the end of surgery.

Regional Analgesia Techniques

At the end of surgery, under ultrasound guidance:

PENG block: 20 ml of 0.25% bupivacaine injected into the musculofascial plane anterior to the psoas tendon and posterior to the pubic ramus LFCN block: 5 ml of 0.25% bupivacaine injected around the lateral femoral cutaneous nerve between the tensor fascia latae and sartorius muscles Lumbar ESP block: 20 ml of 0.25% bupivacaine injected at the anterior fascia of the erector spinae muscle at the L4 transverse process level Postoperative Management Patient-controlled analgesia (PCA) with tramadol (10 mg bolus, 20-minute lockout) was initiated in the recovery unit. Dexketoprofen 50 mg IV was administered as rescue analgesia if NRS ≥4 within the first 20 minutes. Paracetamol 1 g IV every 6 hours was continued on the ward. Ondansetron 4 mg IV (and dexamethasone 4 mg IV if needed) was used for postoperative nausea and vomiting management.

Outcome Measures

Primary outcome:

QoR-15 score at 24 hours postoperatively compared with the baseline preoperative score.

Secondary outcomes:

NRS pain scores (at rest and on movement) at 0, 15, and 30 minutes in the PACU and at 2, 4, 6, 12, and 24 hours on the ward; total tramadol consumption; time to first rescue analgesic; postoperative nausea and vomiting scores; NU-DESC delirium screening; sedation assessment; hemodynamic parameters; and 7- and 30-day mortality and morbidity assessed by telephone follow-up.

Sample Size Sample size calculation was performed based on previously published QoR-15 data. With an effect size of 0.729, 80% power, and a 95% confidence level, a minimum of 31 patients per group (62 total) was required. The analysis was conducted using G*Power version 3.1.9.7.

Inclusion Criteria:

• Age 65 years or older
• ASA physical status I-III
• Scheduled for elective partial or total hip arthroplasty under general anesthesia
• Mini-Mental State Examination (MMSE) score ≥24
• Written informed consent obtained

Exclusion Criteria:

• MMSE score below 24
• Refusal to participate
• Known allergy to local anesthetics or study medications
• Coagulation disorders or anticoagulant use contraindicating regional block
• Infection at the block site
• Pre-existing chronic pain conditions requiring opioid therapy
• ASA physical status IV or above

Elderly patients (≥65 years) undergoing elective partial or total hip arthroplasty under general anesthesia at Fatih Sultan Mehmet Training and Research Hospital, Istanbul, Turkey.

Individual participant data will not be shared due to local ethical and institutional data privacy regulations. Patient confidentiality is protected in accordance with Turkish Personal Data Protection Law (KVKK). Aggregated and de-identified data supporting the findings of this study may be made available upon reasonable request to the corresponding author.