PENG vs. Femoral Nerve Block for Pain Control in Hip Surgery

Overview

The aim of this study is to compare the efficacy of the ultrasound- guided pericapsular nerve group (PENG) block versus the femoral nerve block (FNB) for postoperative pain control in patients undergoing hip surgeries, specifically evaluating pain scores and quadriceps strength.

Study Design: This is a single-center, double-blinded, randomized comparative trial will be conducted on patients for perioperative pain control in patients undergoing hip surgeries conducted at Anesthesia and ICU Department Benha university Hospital during the period from May 2025 to June 2026. Written informed consent will be acquired from all participants. Inclusion Criteria: Patients eligible for inclusion in the study if they met the following criteria: * Aged 40 years or older. * Presenting for hip surgeries * No contraindications to regional anesthesia. * Time of surgery up to 3 hours * ASA I-III * Able to provide written informed consent. * Able to reliably report pain and other symptoms to the research team. * Undergoing elective or emergency hip surgeries. Exclusion Criteria Patients will be excluded from participation in the study if they met any of the following criteria: * Inability to provide first-person consent due to cognitive impairment. * Presence of a language barrier that would preclude reliable reporting of symptoms or understanding study procedures. * More than ASA III. 4 * Previous neurological deficit in the lower limbs. * Local infection at block area. * Lengthy surgeries more than 3 hours. Methods Sample Size Calculation GPower® version 3.1.9.4 program (5) was used for calculations of sample size, statistical calculator based on 95% confidence interval and power of the study 95% with α error 5%, and effect size of 0.55. According to a previous study (6). Based on this assumption, sample size is calculated to be 66 cases (33 cases for each group) were enough to find such a difference. Randomization and Blindness Patients meeting the inclusion criteria will be randomly assigned in a 1:1 ratio to receive either an ultrasound-guided Pericapsular Nerve Group (PENG) block or an ultrasound-guided Femoral Nerve Block (FNB) using an online randomization computer generator. To ensure blinding of the study, the anesthesiologist placing the block will be different from the anesthesiologist managing the patient outcome intraoperatively and postoperatively. Study Interventions The allocated nerve block will be administered 1 hour preoperatively under ultrasound guidance with catheter insertion for continuous nerve block in both groups, a total volume of 20 mL of 0.5% plain marcaine will be injected and continuous infusion rate of 5-10ml per hour of plain bupivacaine 0.25%. All patients will receive standardized spinal anesthesia using 2.5-3 ml of 0.5% hyperbaric bupivacaine with 25 µg fentanyl as an additive. The technique of spinal anesthesia will be through Midline or paramedian approach at L3-L4 or L4-L5 interspace. Sedation with IV midazolam or propofol may be used as needed. Supplemental oxygen will be provided via nasal cannula or face mask. If spinal anesthesia is contraindicated or fails, patients may be converted to general anesthesia and excluded from final analysis. Outcome Measures • The primary outcome will measure: The postoperative pain score, assessed using an 11-point Numeric Rating Scale (NRS; 0 = no pain, 10 = worst pain imaginable), at 0, 1, 2, 6, 12 and 24 hours postoperative (day 0) at rest and during movement. 6 • Secondary outcomes will include: * Postoperative quadriceps strength, and physiotherapy compliance assessed using the knee extension test and the Oxford muscle strength grading scale grouped as intact \[5/5\], reduced \[1-4/5\], and absent \[0/5\] in the recovery unit and on postoperative day 0. * Postoperative opiate consumption, reported for the subsequent 3 postoperative days. * Postoperative complications, classified according to the Clavien- Dindo classification. * Length of hospital stay, measured in days from the day of surgery to the day of discharge. * Patient-reported outcomes (PROMs) assessed on postoperative day 1 using the Patient-Reported Outcomes Measurement Information System (PROMIS) item banks for depression and pain interference, the Brief Pain Inventory (BPI), and the Quality of Recovery (QoR- 15) questionnaire. * Patient satisfaction with pain management, evaluated by the APS on first postoperative day. Patients will also be asked to recall the time of block resolution, defined as the return of motor function if initially impaired and/or the recovery of sensation in the blocked area All patients will be subjected to the following: 1. Preoperative assessment: All patients will undergo a detailed pre-anesthetic check-up, including: 1.1. Detailed history taking including: * Personal history; age, gender, residence, occupation, and special habits. 7 * Relevant comorbidities as hypertension, coronary disease, heart failure, chronic obstructive pulmonary disease and diabetes mellitus. * Mechanism of injury * History of any medical condition or previous hospital admission 1.2. Full clinical examination: 1.2.1. General examination including: * Vital signs: pulse, blood pressure, capillary filling time, respiratory rate and temperature. * Assessment of body mass index (BMI) 1.2.2. Systemic examination including: * Cardiovascular System: For detection of any abnormal heart sounds or murmurs. * Respiratory System: For detection of any abnormal breath sound, and respiratory distress. * Gastrointestinal Tract (GIT) and Abdomen: Presence of organomegaly or ascites. * Central Nervous System (CNS) and Musculoskeletal System: Assessment of pupillary reaction, examination of motor system including power, tone and reflexes. 1.3. Routine laboratory investigations: * Complete blood count (CBC). * Random blood sugar. * Kidney function tests. * Liver function tests 2. Operative The Pericapsular Nerve Group (PENG) block and the Femoral Nerve Block (FNB) will be performed using ultrasound guidance with a 8 high-frequency (10-12 Hz) 38-mm linear ultrasound transducer (Imagic Agile, Peachtree, Georgia). All blocks will be administered by an independent experienced anesthetist who has demonstrated proficiency in performing both PENG and FNB blocks. Prior to the nerve block procedure: The following baseline measurements will be recorded by the administering anesthetist and documented for the study investigators: baseline vital parameters (pulse, blood pressure, respiratory rate), baseline pain score using the Numeric Rating Scale (NRS), and a baseline assessment of quadriceps strength using the Oxford muscle strength grading scale (if feasible given the patient's condition). During the nerve block procedure: The following parameters will be noted: * Allocated Block: The specific nerve block administered (PENG or FNB). * Procedural Duration: Defined as the time from skin puncture to the completion of local anesthetic injection and catheter insertion. * Pain on Injection: Patient-reported pain during the block administration using the NRS (0-10). * Technical Difficulties: Any challenges encountered during block placement, such as multiple needle passes , difficulty visualizing anatomical structures, difficulty in insertion ofcatheter. Following block administration: 9 The anesthetist will assess for the onset of sensory and motor blockade in the anterior thigh and knee and assessing for any quadriceps weakness using the Oxford scale. These findings will be documented and handed over to the investigators. 3. Postoperative Postoperatively, rescue analgesia will be available in the form of intravenous morphine and boluses of local anesthesia in the infusion catheter administered on patient demand or if the Numeric Rating Scale (NRS) pain score is ≥ 4 Measurements The following measurements will be recorded for each participant throughout the study period: 1. Baseline Demographic Characteristics: Age, sex, Body Mass Index (BMI), and ASA physical status will be documented prior to the surgical procedure. 2. Perioperative Hemodynamic Data: Heart rate and Mean Arterial Pressure will be measured and recorded at the following time points: upon arrival in the Post-Anesthesia Care Unit (PACU), and at 1, 2, 4, 8, 12, 18, 24, 48 hours postoperatively. 3. Postoperative Pain Levels: Pain intensity will be assessed using the 11-point Numeric Rating Scale (NRS; 0 = no pain, 10 = worst pain imaginable) at rest and during active movement (specifically during the quadriceps strength test). Assessments will be performed and recorded upon arrival in the PACU, and at 1, 2, 4, 8, 12,24, 48 hours postoperatively. For the purpose of rescue analgesia administration, an NRS score of ≥ 4 will indicate the need for intervention. 4. Time to First Request for Opioid Analgesiapost operative: The time to the first patient-initiated request for opioid rescue medication will be recorded. The dose of the intravenous morphine administered will be documented. 5. Assessment of Sensory and Motor Block: • Sensory Block: Sensory function in the (anterior thigh) will be assessed using pinprick and categorized into three grades: 0 (normal sensation), 1 (decreased sensation), and 2 (absent sensation). This assessment will be performed immediately after block placement in the preoperative area and the resolution of the block will be noted by the patient and recorded. 11 6. 7\. • Motor Block (Quadriceps Strength): Motor function of the quadriceps muscle will be assessed using the Oxford muscle strength grading scale (0-5) immediately after block placement in the preoperative area and at the predefined postoperative time points (recovery unit/day 0 and postoperative day 1). The time to full motor recovery (Oxford scale 5/5) will also be recorded. Degree of Patient Satisfaction: Patient satisfaction with their overall pain management will be assessed on postoperative day 1 using a 5- point Likert scale: (1 = highly satisfied, 2 = satisfied, 3 = neither satisfied nor unsatisfied, 4 = not satisfied, 5 = highly not satisfied) , physiotherapy compliance. Adverse Events: Any undesirable side effects occurring within the first 24 postoperative hours (e.g., nausea, vomiting, bradycardia, hypotension, pruritus, respiratory depression, signs of local anesthetic systemic toxicity) will be documented, along with the treatment administered.

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