Comparison of Femoral Nerve Block and Combined PENG Plus Femoral Nerve Block in Geriatric Hip Surgery

Hip fractures represent one of the most common orthopedic emergencies in the geriatric population and are associated with significant pain, morbidity, and mortality. Effective perioperative analgesia is essential in this fragile patient group, as inadequate pain control may contribute to delayed mobilization, increased cardiopulmonary complications, delirium, and prolonged hospital stay. Traditional opioid-based analgesic strategies are frequently associated with adverse effects such as nausea, vomiting, respiratory depression, and cognitive impairment, particularly in elderly patients. Therefore, regional anesthesia techniques have gained increasing importance in hip fracture surgery.

The hip joint has a complex sensory innervation primarily derived from the femoral, obturator, and accessory obturator nerves. The femoral nerve block is a well-established technique that provides effective analgesia for hip surgery; however, it may be associated with quadriceps muscle weakness due to motor fiber involvement, potentially delaying early mobilization. The pericapsular nerve group (PENG) block, first described in 2018, selectively targets the articular branches of the femoral, obturator, and accessory obturator nerves while largely preserving motor function. Emerging evidence suggests that the PENG block may provide effective analgesia with minimal impact on quadriceps strength.

Despite these findings, the additional analgesic benefit of combining the PENG block with the femoral nerve block remains unclear. This study is designed to evaluate whether the addition of the PENG block to a standard femoral nerve block improves perioperative analgesic outcomes in elderly patients undergoing hip surgery under spinal anesthesia.

This prospective, single-center, randomized controlled trial will be conducted at Ankara Bilkent City Hospital. A total of 68 patients aged 65 years or older, classified as American Society of Anesthesiologists (ASA) physical status I-III, and scheduled for hip surgery under spinal anesthesia will be enrolled after obtaining written informed consent. Patients will be randomly allocated into two groups: Group 1 will receive a preoperative femoral nerve block, and Group 2 will receive a combination of preoperative PENG block and femoral nerve block.

All nerve blocks will be performed approximately 30 minutes before surgery in the designated block area under standard monitoring, including electrocardiography, non-invasive blood pressure measurement, and pulse oximetry. Supplemental oxygen will be administered via nasal cannula at 2 L/min. The PENG block will be performed under ultrasound guidance using an 80-mm block needle, with 20 mL of 0.25% bupivacaine injected incrementally beneath the psoas tendon between the anterior inferior iliac spine and the iliopubic eminence. The femoral nerve block will be performed under ultrasound guidance using a 50-mm block needle, with 20 mL of 0.25% bupivacaine administered incrementally around the femoral nerve.

The time to onset of sensory block will be recorded. Pain intensity will be assessed using the Visual Analog Scale (VAS) at rest and during 15° leg elevation before block placement and 30 minutes after block administration. Hemodynamic parameters, including heart rate, oxygen saturation, and systolic, diastolic, and mean arterial blood pressure, will be recorded at the same time points.

Following block assessment, patients will be transferred to the operating room and positioned in the lateral decubitus position for spinal anesthesia, with the surgical side down. VAS scores will be reassessed during positioning. If a VAS score of 4 or greater is observed during positioning, intravenous fentanyl at a dose of 1 µg/kg will be administered as rescue analgesia. Spinal anesthesia will be performed in the lateral decubitus position using 10 mg (2 mL) of hyperbaric bupivacaine. After intrathecal injection, patients will remain in the lateral position for five minutes before being positioned for surgery.

The duration of the spinal anesthesia procedure will be recorded, including patient positioning, skin antisepsis, sterile draping, intrathecal injection, and needle removal. This approach is intended to evaluate the effect of the applied peripheral nerve blocks on patient comfort and ease of positioning for spinal anesthesia.

Intraoperatively, all patients will be continuously monitored for heart rate, oxygen saturation, electrocardiography, and non-invasive (or invasive if clinically indicated) arterial blood pressure. Postoperatively, patients will be followed in the post-anesthesia care unit for 24 hours.

Postoperative pain will be assessed using VAS at 0, 2, 8, 16, and 24 hours. The time to first analgesic request, total opioid consumption within the first 24 hours, and hemodynamic parameters will be recorded. Postoperative analgesia will be standardized for all patients: intravenous paracetamol 1 g every 6 hours (maximum 4 g/day, or 3 g/day in elderly patients or those with hepatic impairment). If VAS exceeds 4 despite paracetamol administration, intravenous tramadol 50 mg will be administered as rescue analgesia, with a maximum daily dose of 300 mg. Patients will be closely monitored for opioid-related adverse effects, including sedation, nausea, vomiting, and cardiorespiratory complications.

The primary outcome of the study is the comparison of postoperative analgesic efficacy between the femoral nerve block alone and the combined PENG plus femoral nerve block, as assessed by VAS scores and opioid consumption during the first 24 hours. Secondary outcomes include intraoperative and postoperative hemodynamic stability, time to sensory block onset, ease and duration of spinal anesthesia performance, patient comfort during positioning, and time to first postoperative analgesic requirement.

The results of this study are expected to provide valuable evidence regarding the optimal regional anesthesia strategy for perioperative pain management in geriatric hip surgery patients and to contribute to improved analgesic protocols with reduced opioid exposure.