Effect of the Pericapsular Nerve Group (PENG) Block on Postoperative Pain after Elective Total Hip Arthroplasty: study protocol for a randomized, double-blind, 4-arm factorial trial

Effect of the Pericapsular Nerve Group (PENG) Block on Postoperative Pain after Elective Total Hip Arthroplasty: study protocol for a randomized, double-blind, 4-arm factorial trial | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Effect of the Pericapsular Nerve Group (PENG) Block on Postoperative Pain after Elective Total Hip Arthroplasty: study protocol for a randomized, double-blind, 4-arm factorial trial Ulrich Frey, Artem Puzyk, Carla Grundmann, Michal Latocha, Mina Mikhael, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7849040/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 4 You are reading this latest preprint version Abstract Background The pericapsular nerve group (PENG) block has emerged as a promising motor-sparing regional anesthesia technique for hip surgery. However, its definitive role in reducing postoperative pain and opioid consumption following total hip arthroplasty (THA) remains a matter of debate. This study aims to evaluate the analgesic efficacy of the PENG block with and without a lateral femoral cutaneous nerve (LFCN) block. Methods This is a prospective, randomized, double-blind, controlled trial conducted at a single academic center. A total of 168 patients undergoing elective primary THA under general anesthesia will be randomly assigned to one of four groups: (1) low-volume PENG + LFCN block; (2) high-volume PENG + LFCN block; (3) high-volume PENG + sham LFCN; (4) sham PENG + sham LFCN. The primary outcome is the numeric rating scale (NRS) pain score at rest four hours postoperatively. Secondary outcomes include opioid consumption, motor strength, sensory block success, incidence of PONV, patient satisfaction, and adverse events. Discussion This trial will provide evidence on the optimal volume of PENG block and the additive value of LFCN block in multimodal analgesia for THA. Findings may influence future clinical decision-making on regional techniques for motor-sparing analgesia in hip arthroplasty, particularly in the context of “enhanced recovery after surgery”. Protocol version: 1.0, 13 October 2025 Trial registration: German Clinical Trials Register (DRKS): DRKS00037861 Figures Figure 1 Introduction Total hip arthroplasty (THA) is an increasingly common treatment for end-stage hip osteoarthritis, with over 170,000 procedures conducted annually in Germany. While THA is effective in restoring mobility and reducing pain, postoperative pain management remains a critical challenge. Inadequate analgesia can delay mobilization, prolong hospital stays, and hinder functional recovery 1 , 2 . Traditionally, systemic opioids have been used for pain control, but are associated with adverse effects such as nausea, sedation, respiratory depression and risk of addiction 3 . Consequently, regional anesthesia has emerged as a cornerstone of multimodal analgesia, aiming to reduce opioid consumption while preserving function. Common approaches include femoral nerve block and fascia iliaca compartment block. However, both techniques may impair quadriceps strength and increase the risk of falling 4 , 5 . The Pericapsular Nerve Group (PENG) block, first described by Girón-Arango et al. in 2018, targets terminal sensory articular branches of the femoral, obturator, and accessory obturator nerves, providing analgesia of the anterior hip capsule while sparing motor function of the quadriceps femoris muscle 6 , 7 . Multiple recent systematic reviews and meta-analyses of randomized controlled trials demonstrate that the PENG block, compared to no block or sham block, significantly reduces opioid requirements and dynamic pain scores within the first 24 hours postoperatively and may facilitate earlier functional recovery without increasing adverse events such as nausea, vomiting, or quadriceps weakness 8 – 11 . However, the skin of the anterolateral thigh, which is innervated by the lateral femoral cutaneous nerve (LFCN), is generally not covered by the PENG block. This area is often subject to surgical incisions and retractor placement, which can result in persistent postoperative wound pain 12 . The importance of the LFCN is further underscored by imaging studies that reveal significant anatomical variability, suggesting that conventional regional techniques, such as the fascia iliaca block, may more reliably reach the LFCN compared to the standard PENG block 13 . Besides anatomical considerations, the volume of local anesthetic used is an essential parameter that may significantly impact the efficacy and selectivity of the PENG block. Anatomical and cadaveric studies have demonstrated that the spread of the anesthetic along the iliopsoas fascial plane is volume-dependent, potentially determining whether the lateral femoral cutaneous nerve (LFCN) is adequately blocked or not 13 . Smaller volumes may fail to reach the LFCN, leading to incomplete analgesia of the anterolateral thigh. In contrast, larger volumes may result in undesired diffusion to the femoral nerve, causing motor blockade and impairing early postoperative mobilization 14 , 15 . In summary, although various studies have explored the efficacy of PENG block or the role of LFCN involvement individually, there is a notable lack of randomized controlled trials that comprehensively examine both volume titration and the additive effect of LFCN blockade. Furthermore, few studies evaluate both analgesic and functional motor outcomes in a single factorial design. Finally, a recent meta-analysis proposed conducting more randomized controlled trials to evaluate the advantages and disadvantages of PENG block for hip surgeries 10 . In light of these evidence gaps, our study aims to systematically investigate: the impact of low- versus high-volume PENG block on postoperative pain and quadriceps strength; the potential benefit of a supplementary LFCN block in reducing pain and opioid consumption; the combined effect of PENG block volume modulation and the LFCN block on both analgesia and motor function, to identify the most effective and safe regional anesthesia protocol for THA patients. This trial is designed to provide robust evidence that can directly impact clinical guidelines and improve patient outcomes in orthopedic anesthesia. Methods Trial Design and Setting The present study is designed as a prospective, single-center, double-blind, randomized controlled clinical trial. The study will be conducted at the Department of Anesthesiology and the Department of Orthopedic Surgery at St. Anna Hospital Herne, a tertiary care academic hospital affiliated with the Ruhr-University Bochum. The trial utilizes a factorial design comprising four intervention arms to investigate the effects of PENG block volume variation and the addition of LCFN block on postoperative pain and function scores following total hip arthroplasty (THA). The study period will span from patient enrollment through 24 hours postoperatively, with primary and secondary outcomes assessed at specified time intervals. Recruitment will be carried out continuously until the target sample size is achieved. Regular monitoring will be conducted to ensure protocol adherence and data integrity. Eligibility Criteria : Participants who meet the following criteria are eligible for inclusion in the study: adults aged 18 years or older scheduled for elective, primary unilateral total hip arthroplasty under general anesthesia. Prior to enrollment, all participants must provide written informed consent. Exclusion criteria include a known allergy to local anesthetics, pre-existing neurological or muscular disorders affecting the lower extremities, cognitive impairment that precludes reliable reporting, pregnancy, infection at the injection site or participation in another interventional trial within the previous 30 days. Patients with chronic opioid use (daily use exceeding 30 mg oral morphine equivalents for more than three months) or significant hepatic or renal dysfunction (Child-Pugh class B/C, GFR < 30 mL/min) will also be excluded to reduce confounding variables affecting analgesia and recovery. Interventions: Participants will be randomized into one of the four intervention arms: Group A (low-volume PENG + LFCN block) : 10 ml of ropivacaine 0.375% for PENG block; 5 ml bupivacaine 0.5% for LFCN-block. Group B (high-volume PENG + LFCN block) : 20 ml of ropivacaine 0.375% for PENG block; 5 ml bupivacaine 0.5% for LFCN-block. Group C (high-volume PENG + sham LFCN) : 20 ml of ropivacaine 0.375% for PENG block; 5 mL saline for LFCN. Group D (sham PENG + sham LFCN) : 20 ml saline for PENG; 5 mL saline for LFCN. The interventions will be performed by anesthesiologists experienced in regional anesthesia under ultrasound guidance according to group assignment prior to the induction of general anesthesia. To enhance patient comfort during needle placement, 0.5–1.0 µg/kg fentanyl will be administered for sedation in advance. For the PENG block, the needle tip will target the musculofascial plane between the psoas tendon and the pubic ramus. For the LFCN block, the target structure is the fat pad lateral to the sartorius muscle at the level of the anterior superior iliac spine. In both cases, the needle will be advanced in-plane using a lateral-to-medial approach. Sham blocks will be performed in the same manner with saline solution instead of local anesthetics. Blinding will be maintained by an assistant not involved in data collection or care, drawing all injectates in identical syringes. Outcomes The primary outcome of the study is the resting pain intensity at 4 hours postoperatively, assessed using an 11-point numeric rating scale (NRS) ranging from 0 (no pain) to 10 (worst imaginable pain). This time point was chosen to reflect early postoperative pain in a fully conscious patient after the analgesic effect of opioids administered intraoperatively had worn off and before the administration of rescue analgesics. Secondary outcomes include: Opioid consumption during the first 24 hours postoperatively, measured in oral morphine milligram equivalents (MME). Adductor muscle strength , evaluated using the Medical Research Council (MRC) scale at 4 and 24 hours postoperatively. Quadriceps muscle strength , evaluated using the Medical Research Council (MRC) scale at 4 and 24 hours postoperatively. Sensory block efficacy of the LFCN, assessed using pinprick sensation testing on the lateral thigh 10 minutes after the completion of the block. Incidence of postoperative nausea and vomiting (PONV) at 4 and 24 hours after surgery. Patient satisfaction with analgesia and overall satisfaction, measured using a 5-point Likert scale at 24 hours postoperatively. Adverse events , including motor weakness, falls, local anesthetic systemic toxicity (LAST), hematoma and other block-related complications recorded throughout the hospital stay. All outcomes will be documented by blinded assessors not otherwise involved in the anesthesia care of the patients. Data collection will be standardized using predefined forms and electronic records. The outcome measures are designed to evaluate both the analgesic effectiveness and safety of the block combinations. Sample Size Calculation The sample size calculation is based on detecting a clinically meaningful difference in the primary outcome, i.e. the NRS pain score at rest 4 hours after surgery. Based on previous studies of PENG block interventions 8 , 16 – 19 , we anticipate a mean difference of 1.5 points (SD = 2.5) between the groups. To detect this difference with 80% power at a two-sided alpha level of 0.05 and to account for multiple comparisons across four groups, a total of 148 participants (37 per group) are required. Allowing for an approximate 10% dropout rate, we aim to recruit a total of 168 participants (42 per group) to ensure adequate statistical power and robust findings. Participant Timeline Participants will be enrolled following eligibility screening and informed consent obtained during the preoperative anesthesiologic evaluation (Day − 1 to Day 0). Randomization and the study intervention will occur on the day of surgery prior to the induction of anesthesia (Day 0). Primary and secondary outcomes will be measured at designated postoperative time points Preoperative (day − 1 to 0) : eligibility assessment, informed consent, baseline demographics and medical history. Day 0 (surgery day) : group allocation, study intervention (PENG ± LFCN block), LFCN sensory block assessment and general anesthesia. 4 hours after surgery : primary outcome (NRS pain at rest), quadriceps and adductor strength, PONV incidence. 24 hours after surgery : opioid consumption, quadriceps and adductor strength, PONV incidence, patient satisfaction, adverse events. Discharge : final assessment of adverse events and documentation. A SPIRIT schedule (Table 1 , Fig. 1) of enrolment, interventions, and assessments will be provided to illustrate this timeline. The completed SPIRIT checklist is provided as Additional file 1. The activities include eligibility screening, informed consent, randomization, the PENG ± LFCN block intervention, general anesthesia and surgery, pain assessments (NRS at rest), quadriceps/adductor strength, opioid consumption, PONV incidence, patient satisfaction, and adverse event documentation. Data are collected at key time points: enrolment (Day − 1 to 0), allocation (Day 0), postoperative phases (4 hours and 24 hours), and post-discharge. The green bars indicate when each activity occurs. Table 1 SPIRIT Table – Schedule of Enrolment, Interventions and Assessments Study Period Enrolment Allocation Postoperative Phase Post-discharge Timepoints Day − 1 to 0 Day 0 4h post-op 24h / Discharge Enrolment X Eligibility screening X Informed consent X Randomisation X Interventions X PENG ± LCFN Block X General anesthesia & surgery X Assessments X X Demographics X Ressource use X Randomization and Allocation Concealment : Participants will be randomly assigned to one of the four treatment groups in a 1:1:1:1 ratio using a computer-generated randomization schedule with permuted blocks of varying sizes to ensure balance across groups. The allocation sequence will be generated and managed within the REDCap (Research Electronic Data Capture) randomization module, a secure, web-based platform hosted by the study institution, ensuring secure and tamper-proof assignment. Allocation concealment will be maintained through restricted REDCap access granted only to a designated unblinded research team member. This person will access the system immediately before the intervention to obtain the allocation and prepare the corresponding injectates. All other study personnel, as well as patients, surgeons, anesthesiologists and outcome assessors. will remain blinded to group assignments throughout the trial. Data Collection and Management All clinical and outcome data will be collected and managed using REDCap. Standardized case report forms (CRFs) will be implemented directly within REDCap to ensure consistency and reduce variability across data collectors. Trained research staff blinded to group allocation will enter data at pre-specified timepoints (pre-operatively, 4 and 24 hours post-operatively), including documentation of adverse events until discharge. REDCap supports real-time data entry with integrated logic checks, range validations and audit trails to minimize errors and ensure data integrity. Each participant will be assigned a unique trial ID to maintain confidentiality. No identifying data will be stored with the outcomes. Access to identifiable information will be restricted to authorized personnel and governed by role-based permissions. All electronic data will be securely stored in REDCap, in compliance with Good Clinical Practice (GCP) guidelines and institutional data protection policies. Consent forms and paper-based backup documentation, where applicable, will be stored in a locked cabinet on site. Study data will be retained for at least 10 years following the completion of the trial. Statistical Methods Descriptive statistics will be used to summarize patient demographics and baseline characteristics across the four groups. Continuous variables will be presented as mean ± standard deviation or median (interquartile range), depending on the distribution, and compared using ANOVA or Kruskal-Wallis test as appropriate. Categorical variables will be expressed as counts and percentages and analyzed using the chi-square test or Fisher’s exact test. The primary outcome (NRS pain score at 4 hours postoperatively) will be compared among groups using analysis of covariance (ANCOVA), adjusting for baseline covariates as necessary. Pairwise post hoc comparisons will be performed with Bonferroni correction to control for multiple testing. Secondary outcomes will be analyzed using similar statistical techniques, depending on the data type and distribution. Missing data will be addressed using multiple imputation methods if the missingness is above 5%. All analyses will follow the intention-to-treat principle. A two-tailed p-value < 0.05 will be considered statistically significant. Statistical analyses will be conducted using SPSS version 28.0 (IBM Corp., Armonk, NY, USA) or equivalent software. Dissemination Plan The findings of this trial will be disseminated through multiple channels to ensure broad accessibility and impact. The results will be submitted for publication in a high-impact, peer-reviewed anesthesiology or pain management journal, adhering to the CONSORT and SPIRIT guidelines for transparent reporting. Abstracts will be presented at national and international conferences, including meetings of the European Society of Anaesthesiology and Intensive Care (ESAIC), the American Society of Regional Anesthesia and Pain Medicine (ASRA), and other relevant professional forums. Where appropriate, the study results will also be used to inform institutional and national regional anesthesia guidelines. All anonymized data will be made available upon reasonable request to facilitate future meta-analyses or replication studies, in accordance with FAIR data principles. Trial registration, protocol updates and final results will be posted in the public clinical trials registry ( www.drks.de ). Discussion The ultrasound guided pericapsular nerve group (PENG) block was first described as a novel motor-sparing block for hip fracture surgeries, based on a cadaver study that demonstrated the anatomical relationship between the anterior hip capsule and the terminal branches of the femoral, obturator and accessory obturator nerves 7 , 20 . Meanwhile, it has emerged as a promising technique for regional anesthesia in total hip arthroplasty (THA). It appears to provide effective postoperative analgesia while minimizing the risk of motor blockade, especially in conjunction with a lateral femoral cutaneous nerve (LFCN) block 21 . Recent randomized controlled trials and meta-analyses support the efficacy of PENG block in reducing opioid consumption and improving early postoperative pain outcomes without significantly compromising quadriceps or adductor muscle strength 9 , 11 , 22 . The clinical rationale for combining PENG block with an LFCN block is based on the location of the skin incisions and the retractor positioning on the thigh when using the anterolateral approach. Studies have shown that this combination can improve cutaneous analgesia, reduce postoperative opioid requirements, and enhance patient comfort during early mobilization 23 , 24 . Comparisons with other motor-sparing techniques, such as the supra-inguinal fascia iliaca compartment block (S-FICB), suggest similar or superior analgesia with a lower incidence of motor weakness 25 . However, an important limitation in the current evidence is the heterogeneity in local anesthetic volumes used across trials. While most studies employed 20 ml of 0.4–0.5% ropivacaine for the PENG block, others varied between 10 and 40 ml, with or without 3–10 ml for the LFCN block. To date, few studies have directly compared different injection volumes under controlled conditions or systematically evaluated side effects such as inadvertent femoral or obturator nerve blockade. Moreover, to our knowledge, no randomized trial has employed a four-arm factorial design to simultaneously investigate varying volumes and block combinations. Consequently, the optimal volume of local anesthetic that provides effective postoperative analgesia without compromising motor function remains undetermined 26 . Therefore, despite the growing use of these techniques in clinical practice, important questions remain unanswered. Our study directly addresses these knowledge gaps by comparing low- versus high-volume PENG blocks, with and without LFCN block, in a rigorously controlled 4-arm parallel-group design. It also evaluates both pain outcomes and quadriceps as well as adductor motor function using standardized and blinded assessments. The results of this trial have the potential to help define an optimized regional anesthesia strategy for THA, balancing analgesic efficacy with early mobilization and patient safety. Relevance for Clinical Practice Integrating PENG and LCFN blocks into ERAS protocols can directly impact orthopedic anesthesia practice standards. If higher-volume PENG ± LFCN improves pain control with minimal motor impairment, it could inform clinical guidelines. On the other hand, if the analgesic effect is marginal or accompanied by motor impairment, other methods, such as periarticular infiltration, may be preferable. Limitations and Future Directions The single-center design may limit the generalizability of the study, while the 24-hour follow-up may overlook late-onset outcomes, including chronic pain. Further research should focus on long-term functional outcomes, optimal anesthetic concentrations, and patient-centered metrics (e.g., muscle function and ambulation), as well as cost-effectiveness. Trial status Protocol version 1.0 (13 October 2025). Recruitment is planned to begin on November 1st 2025 and is anticipated to be completed by December 2026. Abbreviations PENG Pericapsular Nerve Group THA Total Hip Arthroplasty LFCN Lateral Femoral Cutaneous Nerve NRS Numeric Rating Scale PONV Postoperative Nausea and Vomiting MRC Medical Research Council ERAS Enhanced Recovery After Surgery LAST Local Anaesthetic Systemic Toxicity DRKS Deutsches Register Klinischer Studien RCT Randomized Controlled Trial CRF Case Report Form GCP Good Clinical Practice ICH International Council for Harmonisation SAP Statistical Analysis Plan. Declarations Ethics approval and consent to participate Approved by the Ethics Committee of the Medical Association of Westfalen-Lippe (ÄKWL), reference 2025-600-f-S (1 September 2025). Written informed consent will be obtained from all participants prior to enrolment. Consent for publication Not applicable. No individual person’s data (images, videos, or details) are included. Availability of data and materials The final trial dataset will be accessible to the investigational team (UF, AP, CG, ML, MM, OM, TK) under institutional data governance. De-identified data and the statistical code will be made available upon reasonable request after publication, subject to data protection and ethics approvals. Competing interests The authors declare that they have no competing interests. Funding This investigator-initiated trial is funded by internal departmental resources of the Department of Anesthesiology and Intensive Care Medicine, Marien Hospital Herne, Ruhr-University Bochum. 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Hu J, Wang Q, Hu J, Kang P, Yang J. Efficacy of Ultrasound-Guided Pericapsular Nerve Group (PENG) Block Combined With Local Infiltration Analgesia on Postoperative Pain After Total Hip Arthroplasty: A Prospective, Double-Blind, Randomized Controlled Trial. J Arthroplast. 2023;38:1096–103. https://doi.org/10.1016/j.arth.2022.12.023 . Supplementary Files SpiritChecklistFormFrey.docx Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 02 Feb, 2026 Reviewers invited by journal 29 Jan, 2026 Editor assigned by journal 07 Nov, 2025 First submitted to journal 06 Nov, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7849040","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":582407869,"identity":"b77ade20-1582-4571-96d0-7d6cd85f3e6b","order_by":0,"name":"Ulrich Frey","email":"data:image/png;base64,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","orcid":"https://orcid.org/0000-0003-2961-6629","institution":"Ruhr-Universitat Bochum Medizinische Fakultat","correspondingAuthor":true,"prefix":"","firstName":"Ulrich","middleName":"","lastName":"Frey","suffix":""},{"id":582407870,"identity":"72febaa1-9ceb-4856-8ae8-1af30bcd93e6","order_by":1,"name":"Artem Puzyk","email":"","orcid":"","institution":"Ruhr-Universitat Bochum","correspondingAuthor":false,"prefix":"","firstName":"Artem","middleName":"","lastName":"Puzyk","suffix":""},{"id":582407871,"identity":"6abb1041-798d-4744-84d1-7b7ef3f52a17","order_by":2,"name":"Carla Grundmann","email":"","orcid":"","institution":"Ruhr-Universitat Bochum","correspondingAuthor":false,"prefix":"","firstName":"Carla","middleName":"","lastName":"Grundmann","suffix":""},{"id":582407872,"identity":"47d57f74-3df1-41a4-a172-7430063f5ea2","order_by":3,"name":"Michal Latocha","email":"","orcid":"","institution":"Ruhr-Universitat Bochum","correspondingAuthor":false,"prefix":"","firstName":"Michal","middleName":"","lastName":"Latocha","suffix":""},{"id":582407873,"identity":"390bbaa3-f6a7-49bc-9f9e-7da3e71b090a","order_by":4,"name":"Mina Mikhael","email":"","orcid":"","institution":"S. Anna Hospital: S Anna hospital","correspondingAuthor":false,"prefix":"","firstName":"Mina","middleName":"","lastName":"Mikhael","suffix":""},{"id":582407874,"identity":"f2ef1052-5223-43a8-9f3b-89de38752a2c","order_by":5,"name":"Oliver Meyer","email":"","orcid":"","institution":"S. Anna Hospital: S Anna hospital","correspondingAuthor":false,"prefix":"","firstName":"Oliver","middleName":"","lastName":"Meyer","suffix":""},{"id":582407875,"identity":"467faeb4-bf6e-4836-8b78-c85e01d27529","order_by":6,"name":"Thomas Komanek","email":"","orcid":"","institution":"S. Anna Hospital: S Anna hospital","correspondingAuthor":false,"prefix":"","firstName":"Thomas","middleName":"","lastName":"Komanek","suffix":""}],"badges":[],"createdAt":"2025-10-13 12:27:08","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7849040/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7849040/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":101657568,"identity":"7af33444-4481-42e7-be6a-782061e0c636","added_by":"auto","created_at":"2026-02-02 10:19:41","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":193362,"visible":true,"origin":"","legend":"\u003cp\u003eTimeline of the PENG Block trial, detailing the schedule of enrolment, interventions, and assessments.\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7849040/v1/cfc0bc92257492d361eb7493.jpeg"},{"id":101753301,"identity":"a4dcb957-a27c-4d64-babe-816e288399ec","added_by":"auto","created_at":"2026-02-03 10:39:39","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":951876,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7849040/v1/e1b07c18-92c7-49eb-ba66-2b8535a5cf6b.pdf"},{"id":101657570,"identity":"a7b4782e-f3db-4379-96fa-26c40bbd50e2","added_by":"auto","created_at":"2026-02-02 10:19:41","extension":"docx","order_by":4,"title":"","display":"","copyAsset":false,"role":"supplement","size":38813,"visible":true,"origin":"","legend":"","description":"","filename":"SpiritChecklistFormFrey.docx","url":"https://assets-eu.researchsquare.com/files/rs-7849040/v1/d2c1eca22040f8cf9ee6d94c.docx"}],"financialInterests":"","formattedTitle":"Effect of the Pericapsular Nerve Group (PENG) Block on Postoperative Pain after Elective Total Hip Arthroplasty: study protocol for a randomized, double-blind, 4-arm factorial trial","fulltext":[{"header":"Introduction","content":"\u003cp\u003eTotal hip arthroplasty (THA) is an increasingly common treatment for end-stage hip osteoarthritis, with over 170,000 procedures conducted annually in Germany. While THA is effective in restoring mobility and reducing pain, postoperative pain management remains a critical challenge. Inadequate analgesia can delay mobilization, prolong hospital stays, and hinder functional recovery\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e,\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eTraditionally, systemic opioids have been used for pain control, but are associated with adverse effects such as nausea, sedation, respiratory depression and risk of addiction\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e. Consequently, regional anesthesia has emerged as a cornerstone of multimodal analgesia, aiming to reduce opioid consumption while preserving function. Common approaches include femoral nerve block and fascia iliaca compartment block. However, both techniques may impair quadriceps strength and increase the risk of falling\u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e,\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe Pericapsular Nerve Group (PENG) block, first described by Gir\u0026oacute;n-Arango et al. in 2018, targets terminal sensory articular branches of the femoral, obturator, and accessory obturator nerves, providing analgesia of the anterior hip capsule while sparing motor function of the quadriceps femoris muscle\u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e,\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/sup\u003e. Multiple recent systematic reviews and meta-analyses of randomized controlled trials demonstrate that the PENG block, compared to no block or sham block, significantly reduces opioid requirements and dynamic pain scores within the first 24 hours postoperatively and may facilitate earlier functional recovery without increasing adverse events such as nausea, vomiting, or quadriceps weakness\u003csup\u003e\u003cspan additionalcitationids=\"CR9 CR10\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e. However, the skin of the anterolateral thigh, which is innervated by the lateral femoral cutaneous nerve (LFCN), is generally not covered by the PENG block. This area is often subject to surgical incisions and retractor placement, which can result in persistent postoperative wound pain\u003csup\u003e\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e. The importance of the LFCN is further underscored by imaging studies that reveal significant anatomical variability, suggesting that conventional regional techniques, such as the fascia iliaca block, may more reliably reach the LFCN compared to the standard PENG block\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eBesides anatomical considerations, the volume of local anesthetic used is an essential parameter that may significantly impact the efficacy and selectivity of the PENG block. Anatomical and cadaveric studies have demonstrated that the spread of the anesthetic along the iliopsoas fascial plane is volume-dependent, potentially determining whether the lateral femoral cutaneous nerve (LFCN) is adequately blocked or not \u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e. Smaller volumes may fail to reach the LFCN, leading to incomplete analgesia of the anterolateral thigh. In contrast, larger volumes may result in undesired diffusion to the femoral nerve, causing motor blockade and impairing early postoperative mobilization\u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e,\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eIn summary, although various studies have explored the efficacy of PENG block or the role of LFCN involvement individually, there is a notable lack of randomized controlled trials that comprehensively examine both volume titration and the additive effect of LFCN blockade. Furthermore, few studies evaluate both analgesic and functional motor outcomes in a single factorial design. Finally, a recent meta-analysis proposed conducting more randomized controlled trials to evaluate the advantages and disadvantages of PENG block for hip surgeries\u003csup\u003e\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eIn light of these evidence gaps, our study aims to systematically investigate:\u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003ethe impact of low- versus high-volume PENG block on postoperative pain and quadriceps strength;\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003ethe potential benefit of a supplementary LFCN block in reducing pain and opioid consumption;\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003ethe combined effect of PENG block volume modulation and the LFCN block on both analgesia and motor function, to identify the most effective and safe regional anesthesia protocol for THA patients.\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003cp\u003e This trial is designed to provide robust evidence that can directly impact clinical guidelines and improve patient outcomes in orthopedic anesthesia.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e\u003cstrong\u003eTrial Design and Setting\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe present study is designed as a prospective, single-center, double-blind, randomized controlled clinical trial. The study will be conducted at the Department of Anesthesiology and the Department of Orthopedic Surgery at St. Anna Hospital Herne, a tertiary care academic hospital affiliated with the Ruhr-University Bochum. The trial utilizes a factorial design comprising four intervention arms to investigate the effects of PENG block volume variation and the addition of LCFN block on postoperative pain and function scores following total hip arthroplasty (THA). The study period will span from patient enrollment through 24 hours postoperatively, with primary and secondary outcomes assessed at specified time intervals. Recruitment will be carried out continuously until the target sample size is achieved. Regular monitoring will be conducted to ensure protocol adherence and data integrity.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEligibility Criteria\u003c/strong\u003e: Participants who meet the following criteria are eligible for inclusion in the study: adults aged 18 years or older scheduled for elective, primary unilateral total hip arthroplasty under general anesthesia. Prior to enrollment, all participants must provide written informed consent. Exclusion criteria include a known allergy to local anesthetics, pre-existing neurological or muscular disorders affecting the lower extremities, cognitive impairment that precludes reliable reporting, pregnancy, infection at the injection site or participation in another interventional trial within the previous 30 days. Patients with chronic opioid use (daily use exceeding 30 mg oral morphine equivalents for more than three months) or significant hepatic or renal dysfunction (Child-Pugh class B/C, GFR\u0026thinsp;\u0026lt;\u0026thinsp;30 mL/min) will also be excluded to reduce confounding variables affecting analgesia and recovery.\u003c/p\u003e\n\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\n\u003ch2\u003eInterventions:\u003c/h2\u003e\n\u003cp\u003eParticipants will be randomized into one of the four intervention arms:\u003c/p\u003e\n\u003col\u003e\n\u003cli\u003e\n\u003cp\u003e\u003cstrong\u003eGroup A (low-volume PENG\u0026thinsp;+\u0026thinsp;LFCN block)\u003c/strong\u003e: 10 ml of ropivacaine 0.375% for PENG block; 5 ml bupivacaine 0.5% for LFCN-block.\u003c/p\u003e\n\u003c/li\u003e\n\u003cli\u003e\n\u003cp\u003e\u003cstrong\u003eGroup B (high-volume PENG\u0026thinsp;+\u0026thinsp;LFCN block)\u003c/strong\u003e: 20 ml of ropivacaine 0.375% for PENG block; 5 ml bupivacaine 0.5% for LFCN-block.\u003c/p\u003e\n\u003c/li\u003e\n\u003cli\u003e\n\u003cp\u003e\u003cstrong\u003eGroup C (high-volume PENG\u0026thinsp;+\u0026thinsp;sham LFCN)\u003c/strong\u003e: 20 ml of ropivacaine 0.375% for PENG block; 5 mL saline for LFCN.\u003c/p\u003e\n\u003c/li\u003e\n\u003cli\u003e\n\u003cp\u003e\u003cstrong\u003eGroup D (sham PENG\u0026thinsp;+\u0026thinsp;sham LFCN)\u003c/strong\u003e: 20 ml saline for PENG; 5 mL saline for LFCN.\u003c/p\u003e\n\u003c/li\u003e\n\u003c/ol\u003e\n\u003cp\u003eThe interventions will be performed by anesthesiologists experienced in regional anesthesia under ultrasound guidance according to group assignment prior to the induction of general anesthesia. To enhance patient comfort during needle placement, 0.5\u0026ndash;1.0 \u0026micro;g/kg fentanyl will be administered for sedation in advance. For the PENG block, the needle tip will target the musculofascial plane between the psoas tendon and the pubic ramus. For the LFCN block, the target structure is the fat pad lateral to the sartorius muscle at the level of the anterior superior iliac spine. In both cases, the needle will be advanced in-plane using a lateral-to-medial approach. Sham blocks will be performed in the same manner with saline solution instead of local anesthetics. Blinding will be maintained by an assistant not involved in data collection or care, drawing all injectates in identical syringes.\u003c/p\u003e\n\u003c/div\u003e\n\u003ch3\u003eOutcomes\u003c/h3\u003e\n\u003cp\u003eThe primary outcome of the study is the resting pain intensity at 4 hours postoperatively, assessed using an 11-point numeric rating scale (NRS) ranging from 0 (no pain) to 10 (worst imaginable pain). This time point was chosen to reflect early postoperative pain in a fully conscious patient after the analgesic effect of opioids administered intraoperatively had worn off and before the administration of rescue analgesics.\u003c/p\u003e\n\u003cp\u003eSecondary outcomes include:\u003c/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cp\u003e\u003cstrong\u003eOpioid consumption\u003c/strong\u003e during the first 24 hours postoperatively, measured in oral morphine milligram equivalents (MME).\u003c/p\u003e\n\u003c/li\u003e\n\u003cli\u003e\n\u003cp\u003e\u003cstrong\u003eAdductor muscle strength\u003c/strong\u003e, evaluated using the Medical Research Council (MRC) scale at 4 and 24 hours postoperatively.\u003c/p\u003e\n\u003c/li\u003e\n\u003cli\u003e\n\u003cp\u003e\u003cstrong\u003eQuadriceps muscle strength\u003c/strong\u003e, evaluated using the Medical Research Council (MRC) scale at 4 and 24 hours postoperatively.\u003c/p\u003e\n\u003c/li\u003e\n\u003cli\u003e\n\u003cp\u003e\u003cstrong\u003eSensory block efficacy\u003c/strong\u003e of the LFCN, assessed using pinprick sensation testing on the lateral thigh 10 minutes after the completion of the block.\u003c/p\u003e\n\u003c/li\u003e\n\u003cli\u003e\n\u003cp\u003e\u003cstrong\u003eIncidence of postoperative nausea and vomiting (PONV)\u003c/strong\u003e at 4 and 24 hours after surgery.\u003c/p\u003e\n\u003c/li\u003e\n\u003cli\u003e\n\u003cp\u003e\u003cstrong\u003ePatient satisfaction\u003c/strong\u003e with analgesia and overall satisfaction, measured using a 5-point Likert scale at 24 hours postoperatively.\u003c/p\u003e\n\u003c/li\u003e\n\u003cli\u003e\n\u003cp\u003e\u003cstrong\u003eAdverse events\u003c/strong\u003e, including motor weakness, falls, local anesthetic systemic toxicity (LAST), hematoma and other block-related complications recorded throughout the hospital stay.\u003c/p\u003e\n\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eAll outcomes will be documented by blinded assessors not otherwise involved in the anesthesia care of the patients. Data collection will be standardized using predefined forms and electronic records. The outcome measures are designed to evaluate both the analgesic effectiveness and safety of the block combinations.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSample Size Calculation\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe sample size calculation is based on detecting a clinically meaningful difference in the primary outcome, i.e. the NRS pain score at rest 4 hours after surgery. Based on previous studies of PENG block interventions\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e8\u003c/span\u003e,\u003cspan class=\"CitationRef\"\u003e16\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e, we anticipate a mean difference of 1.5 points (SD\u0026thinsp;=\u0026thinsp;2.5) between the groups. To detect this difference with 80% power at a two-sided alpha level of 0.05 and to account for multiple comparisons across four groups, a total of 148 participants (37 per group) are required. Allowing for an approximate 10% dropout rate, we aim to recruit a total of 168 participants (42 per group) to ensure adequate statistical power and robust findings.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eParticipant Timeline\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eParticipants will be enrolled following eligibility screening and informed consent obtained during the preoperative anesthesiologic evaluation (Day \u0026minus;\u0026thinsp;1 to Day 0). Randomization and the study intervention will occur on the day of surgery prior to the induction of anesthesia (Day 0). Primary and secondary outcomes will be measured at designated postoperative time points\u003c/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cp\u003e\u003cstrong\u003ePreoperative (day \u0026minus;\u0026thinsp;1 to 0)\u003c/strong\u003e: eligibility assessment, informed consent, baseline demographics and medical history.\u003c/p\u003e\n\u003c/li\u003e\n\u003cli\u003e\n\u003cp\u003e\u003cstrong\u003eDay 0 (surgery day)\u003c/strong\u003e: group allocation, study intervention (PENG\u0026thinsp;\u0026plusmn;\u0026thinsp;LFCN block), LFCN sensory block assessment and general anesthesia.\u003c/p\u003e\n\u003c/li\u003e\n\u003cli\u003e\n\u003cp\u003e\u003cstrong\u003e4 hours after surgery\u003c/strong\u003e: primary outcome (NRS pain at rest), quadriceps and adductor strength, PONV incidence.\u003c/p\u003e\n\u003c/li\u003e\n\u003cli\u003e\n\u003cp\u003e\u003cstrong\u003e24 hours after surgery\u003c/strong\u003e: opioid consumption, quadriceps and adductor strength, PONV incidence, patient satisfaction, adverse events.\u003c/p\u003e\n\u003c/li\u003e\n\u003cli\u003e\n\u003cp\u003e\u003cstrong\u003eDischarge\u003c/strong\u003e: final assessment of adverse events and documentation.\u003c/p\u003e\n\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eA SPIRIT schedule (Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e, Fig.\u0026nbsp;1) of enrolment, interventions, and assessments will be provided to illustrate this timeline. The completed SPIRIT checklist is provided as Additional file 1.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe activities include eligibility screening, informed consent, randomization, the PENG\u0026thinsp;\u0026plusmn;\u0026thinsp;LFCN block intervention, general anesthesia and surgery, pain assessments (NRS at rest), quadriceps/adductor strength, opioid consumption, PONV incidence, patient satisfaction, and adverse event documentation. Data are collected at key time points: enrolment (Day \u0026minus;\u0026thinsp;1 to 0), allocation (Day 0), postoperative phases (4 hours and 24 hours), and post-discharge. The green bars indicate when each activity occurs.\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n\u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n\u003ctable id=\"Tab1\" border=\"1\"\u003e\u003ccaption\u003e\n\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n\u003cdiv class=\"CaptionContent\"\u003e\n\u003cp\u003eSPIRIT Table \u0026ndash; Schedule of Enrolment, Interventions and Assessments\u003c/p\u003e\n\u003c/div\u003e\n\u003c/caption\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eStudy Period\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eEnrolment\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eAllocation\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003ePostoperative Phase\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003ePost-discharge\u003c/p\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eTimepoints\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eDay \u0026minus;\u0026thinsp;1 to 0\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eDay 0\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e4h post-op\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e24h / Discharge\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eEnrolment\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eX\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eEligibility screening\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eX\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eInformed consent\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eX\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eRandomisation\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eX\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eInterventions\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eX\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003ePENG\u0026thinsp;\u0026plusmn;\u0026thinsp;LCFN Block\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eX\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eGeneral anesthesia \u0026amp; surgery\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eX\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eAssessments\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eX\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eX\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eDemographics\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eX\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eRessource use\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eX\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cstrong\u003eRandomization and Allocation Concealment\u003c/strong\u003e: Participants will be randomly assigned to one of the four treatment groups in a 1:1:1:1 ratio using a computer-generated randomization schedule with permuted blocks of varying sizes to ensure balance across groups. The allocation sequence will be generated and managed within the REDCap (Research Electronic Data Capture) randomization module, a secure, web-based platform hosted by the study institution, ensuring secure and tamper-proof assignment. Allocation concealment will be maintained through restricted REDCap access granted only to a designated unblinded research team member. This person will access the system immediately before the intervention to obtain the allocation and prepare the corresponding injectates. All other study personnel, as well as patients, surgeons, anesthesiologists and outcome assessors. will remain blinded to group assignments throughout the trial.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Collection and Management\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll clinical and outcome data will be collected and managed using REDCap. Standardized case report forms (CRFs) will be implemented directly within REDCap to ensure consistency and reduce variability across data collectors. Trained research staff blinded to group allocation will enter data at pre-specified timepoints (pre-operatively, 4 and 24 hours post-operatively), including documentation of adverse events until discharge. REDCap supports real-time data entry with integrated logic checks, range validations and audit trails to minimize errors and ensure data integrity. Each participant will be assigned a unique trial ID to maintain confidentiality. No identifying data will be stored with the outcomes. Access to identifiable information will be restricted to authorized personnel and governed by role-based permissions. All electronic data will be securely stored in REDCap, in compliance with Good Clinical Practice (GCP) guidelines and institutional data protection policies. Consent forms and paper-based backup documentation, where applicable, will be stored in a locked cabinet on site. Study data will be retained for at least 10 years following the completion of the trial.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatistical Methods\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDescriptive statistics will be used to summarize patient demographics and baseline characteristics across the four groups. Continuous variables will be presented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation or median (interquartile range), depending on the distribution, and compared using ANOVA or Kruskal-Wallis test as appropriate. Categorical variables will be expressed as counts and percentages and analyzed using the chi-square test or Fisher\u0026rsquo;s exact test.\u003c/p\u003e\n\u003cp\u003eThe primary outcome (NRS pain score at 4 hours postoperatively) will be compared among groups using analysis of covariance (ANCOVA), adjusting for baseline covariates as necessary. Pairwise post hoc comparisons will be performed with Bonferroni correction to control for multiple testing. Secondary outcomes will be analyzed using similar statistical techniques, depending on the data type and distribution.\u003c/p\u003e\n\u003cp\u003eMissing data will be addressed using multiple imputation methods if the missingness is above 5%. All analyses will follow the intention-to-treat principle. A two-tailed p-value\u0026thinsp;\u0026lt;\u0026thinsp;0.05 will be considered statistically significant. Statistical analyses will be conducted using SPSS version 28.0 (IBM Corp., Armonk, NY, USA) or equivalent software.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDissemination Plan\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe findings of this trial will be disseminated through multiple channels to ensure broad accessibility and impact. The results will be submitted for publication in a high-impact, peer-reviewed anesthesiology or pain management journal, adhering to the CONSORT and SPIRIT guidelines for transparent reporting. Abstracts will be presented at national and international conferences, including meetings of the European Society of Anaesthesiology and Intensive Care (ESAIC), the American Society of Regional Anesthesia and Pain Medicine (ASRA), and other relevant professional forums.\u003c/p\u003e\n\u003cp\u003eWhere appropriate, the study results will also be used to inform institutional and national regional anesthesia guidelines. All anonymized data will be made available upon reasonable request to facilitate future meta-analyses or replication studies, in accordance with FAIR data principles. Trial registration, protocol updates and final results will be posted in the public clinical trials registry (\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ewww.drks.de\u003c/span\u003e\u003c/span\u003e).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe ultrasound guided pericapsular nerve group (PENG) block was first described as a novel motor-sparing block for hip fracture surgeries, based on a cadaver study that demonstrated the anatomical relationship between the anterior hip capsule and the terminal branches of the femoral, obturator and accessory obturator nerves \u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e,\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e. Meanwhile, it has emerged as a promising technique for regional anesthesia in total hip arthroplasty (THA). It appears to provide effective postoperative analgesia while minimizing the risk of motor blockade, especially in conjunction with a lateral femoral cutaneous nerve (LFCN) block\u003csup\u003e\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e. Recent randomized controlled trials and meta-analyses support the efficacy of PENG block in reducing opioid consumption and improving early postoperative pain outcomes without significantly compromising quadriceps or adductor muscle strength\u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e,\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e,\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u003c/sup\u003e. The clinical rationale for combining PENG block with an LFCN block is based on the location of the skin incisions and the retractor positioning on the thigh when using the anterolateral approach. Studies have shown that this combination can improve cutaneous analgesia, reduce postoperative opioid requirements, and enhance patient comfort during early mobilization\u003csup\u003e\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e,\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/sup\u003e. Comparisons with other motor-sparing techniques, such as the supra-inguinal fascia iliaca compartment block (S-FICB), suggest similar or superior analgesia with a lower incidence of motor weakness\u003csup\u003e\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eHowever, an important limitation in the current evidence is the heterogeneity in local anesthetic volumes used across trials. While most studies employed 20 ml of 0.4\u0026ndash;0.5% ropivacaine for the PENG block, others varied between 10 and 40 ml, with or without 3\u0026ndash;10 ml for the LFCN block. To date, few studies have directly compared different injection volumes under controlled conditions or systematically evaluated side effects such as inadvertent femoral or obturator nerve blockade. Moreover, to our knowledge, no randomized trial has employed a four-arm factorial design to simultaneously investigate varying volumes and block combinations. Consequently, the optimal volume of local anesthetic that provides effective postoperative analgesia without compromising motor function remains undetermined\u003csup\u003e\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eTherefore, despite the growing use of these techniques in clinical practice, important questions remain unanswered. Our study directly addresses these knowledge gaps by comparing low- versus high-volume PENG blocks, with and without LFCN block, in a rigorously controlled 4-arm parallel-group design. It also evaluates both pain outcomes and quadriceps as well as adductor motor function using standardized and blinded assessments. The results of this trial have the potential to help define an optimized regional anesthesia strategy for THA, balancing analgesic efficacy with early mobilization and patient safety.\u003c/p\u003e \u003cp\u003e\u003cb\u003eRelevance for Clinical Practice\u003c/b\u003e Integrating PENG and LCFN blocks into ERAS protocols can directly impact orthopedic anesthesia practice standards. If higher-volume PENG\u0026thinsp;\u0026plusmn;\u0026thinsp;LFCN improves pain control with minimal motor impairment, it could inform clinical guidelines. On the other hand, if the analgesic effect is marginal or accompanied by motor impairment, other methods, such as periarticular infiltration, may be preferable.\u003c/p\u003e \u003cp\u003e \u003cb\u003eLimitations and Future Directions\u003c/b\u003e The single-center design may limit the generalizability of the study, while the 24-hour follow-up may overlook late-onset outcomes, including chronic pain. Further research should focus on long-term functional outcomes, optimal anesthetic concentrations, and patient-centered metrics (e.g., muscle function and ambulation), as well as cost-effectiveness.\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eTrial status\u003c/strong\u003e \u003cp\u003eProtocol version 1.0 (13 October 2025). Recruitment is planned to begin on November 1st 2025 and is anticipated to be completed by December 2026.\u003c/p\u003e \u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003ePENG\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003ePericapsular Nerve Group\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eTHA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eTotal Hip Arthroplasty\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eLFCN\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eLateral Femoral Cutaneous Nerve\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eNRS\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eNumeric Rating Scale\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003ePONV\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003ePostoperative Nausea and Vomiting\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eMRC\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eMedical Research Council\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eERAS\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eEnhanced Recovery After Surgery\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eLAST\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eLocal Anaesthetic Systemic Toxicity\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eDRKS\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eDeutsches Register Klinischer Studien\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eRCT\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eRandomized Controlled Trial\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eCRF\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eCase Report Form\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eGCP\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eGood Clinical Practice\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eICH\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eInternational Council for Harmonisation\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eSAP\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eStatistical Analysis Plan.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003eEthics approval and consent to participate\u003c/p\u003e\n\u003cp\u003eApproved by the Ethics Committee of the Medical Association of Westfalen-Lippe (ÄKWL), reference 2025-600-f-S (1 September 2025). Written informed consent will be obtained from all participants prior to enrolment.\u003c/p\u003e\n\u003cp\u003eConsent for publication\u003c/p\u003e\n\u003cp\u003eNot applicable. No individual person’s data (images, videos, or details) are included.\u003c/p\u003e\n\u003cp\u003eAvailability of data and materials\u003c/p\u003e\n\u003cp\u003eThe final trial dataset will be accessible to the investigational team (UF, AP, CG, ML, MM, OM, TK) under institutional data governance. De-identified data and the statistical code will be made available upon reasonable request after publication, subject to data protection and ethics approvals.\u003c/p\u003e\n\u003cp\u003eCompeting interests\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003eFunding\u003c/p\u003e\n\u003cp\u003eThis investigator-initiated trial is funded by internal departmental resources of the Department of Anesthesiology and Intensive Care Medicine, Marien Hospital Herne, Ruhr-University Bochum. The funder had no role in study design; data collection, analysis, or interpretation; manuscript writing; or the decision to submit.\u003c/p\u003e\n\u003cp\u003eAuthors’ contributions\u003c/p\u003e\n\u003cp\u003eUHF is the Chief Investigator; conceived the study and led protocol development. AP, CG, ML, MM, OM, TK contributed to study design, outcomes, and procedures. AP/CG drafted the methods; UHF/ML/TK refined the statistical plan and clinical endpoints. All authors read and approved the final manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eChou R, Gordon DB, de Leon-Casasola OA, Rosenberg JM, Bickler S, Brennan T, Carter T, Cassidy CL, Chittenden EH, Degenhardt E, et al. Management of Postoperative Pain: A Clinical Practice Guideline From the American Pain Society, the American Society of Regional Anesthesia and Pain Medicine, and the American Society of Anesthesiologists\u0026rsquo; Committee on Regional Anesthesia, Executive Committee, and Administrative Council. 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BMC Anesthesiol. 2023;23:233. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1186/s12871-023-02190-1\u003c/span\u003e\u003cspan address=\"10.1186/s12871-023-02190-1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKong M, Tang Y, Tong F, Guo H, Zhang XL, Zhou L, Ni H, Wang B, Liu Y, Liu J. The analgesic efficacy of pericapsular nerve group block in patients with intertrochanteric femur fracture: A randomized controlled trial. PLoS ONE. 2022;17:e0275793. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1371/journal.pone.0275793\u003c/span\u003e\u003cspan address=\"10.1371/journal.pone.0275793\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLIN X, Liu CW, Goh QY, Sim EY, Chan SKT, Lim ZW, Chan DXH. Pericapsular nerve group (PENG) block for early pain management of elderly patients with hip fracture: a single-center double-blind randomized controlled trial. Reg Anesth Pain Med. 2023;48:535\u0026ndash;9. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1136/rapm-2022-104117\u003c/span\u003e\u003cspan address=\"10.1136/rapm-2022-104117\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEppel B, Schneider MM, Gebhardt S, Balcarek P, Sobau C, Matos JW, Zimmerer A. Pericapsular Nerve Group Block Leads to Small but Consistent Reductions in Pain Between 18 and 24 Hours Postoperatively in Hip Arthroscopy for Femoroacetabular Impingement Surgery: A Prospective, Randomized Controlled Clinical Trial. Arthrosc : J Arthrosc Relat Surg. 2024;40:373\u0026ndash;80. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.arthro.2023.06.016\u003c/span\u003e\u003cspan address=\"10.1016/j.arthro.2023.06.016\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGir\u0026oacute;n-Arango L, Peng PWH, Chin K. Pericapsular Nerve Group (PENG) Block for Hip Fracture. Reg Anesth Pain Med. 2018;43:859\u0026ndash;63.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRoy R, Agarwal G, Pradhan C, Kuanar D. Total postoperative analgesia for hip surgeries, PENG block with LFCN block. Reg. Anesth Pain Med. 2019;44:684\u0026ndash;684. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1136/rapm-2019-100454\u003c/span\u003e\u003cspan address=\"10.1136/rapm-2019-100454\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKukreja P, Uppal V, Kofskey AM, Feinstein J, Northern T, Davis C, Morgan CJ, Kalagara H. Quality of recovery after pericapsular nerve group (PENG) block for primary total hip arthroplasty under spinal anaesthesia: a randomised controlled observer-blinded trial. Br J Anaesth. 2023;130:773\u0026ndash;9. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.bja.2023.02.017\u003c/span\u003e\u003cspan address=\"10.1016/j.bja.2023.02.017\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTian Y, Lu Q, Yuan Y, Hu Z, Li W, Li K. The effect of pericapsular nerve group block and lateral femoral cutaneous nerve block on postoperative recovery after hip arthroplasty. Sci Rep. 2025;15:19913. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1038/s41598-025-04699-6\u003c/span\u003e\u003cspan address=\"10.1038/s41598-025-04699-6\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePascarella G, Costa F, Strumia A, Ruggiero A, Remore LM, Lanteri T, Hazboun A, Longo F, Gargano F, Schiavoni L, et al. Lateral Femoral Cutaneous Nerve Block or Wound Infiltration Combined with Pericapsular Nerve Group (PENG) Block for Postoperative Analgesia following Total Hip Arthroplasty through Posterior Approach: A Randomized Controlled Trial. J Clin Med. 2024;13:2674. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3390/jcm13092674\u003c/span\u003e\u003cspan address=\"10.3390/jcm13092674\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVetrone F, Saglietti F, Galimberti A, Pezzi A, Umbrello M, Cuttone G, Via LL, Vetrugno L, Deana C, Girombelli A. Pericapsular Nerve Group Block Plus Lateral Femoral Cutaneous Nerve Block vs. Fascia Iliaca Compartment Block in Hip Replacement Surgery. J Clin Med. 2025;14:984. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3390/jcm14030984\u003c/span\u003e\u003cspan address=\"10.3390/jcm14030984\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHu J, Wang Q, Hu J, Kang P, Yang J. Efficacy of Ultrasound-Guided Pericapsular Nerve Group (PENG) Block Combined With Local Infiltration Analgesia on Postoperative Pain After Total Hip Arthroplasty: A Prospective, Double-Blind, Randomized Controlled Trial. J Arthroplast. 2023;38:1096\u0026ndash;103. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.arth.2022.12.023\u003c/span\u003e\u003cspan address=\"10.1016/j.arth.2022.12.023\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"trials","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"trls","sideBox":"Learn more about [Trials](http://trialsjournal.biomedcentral.com/)","snPcode":"13063","submissionUrl":"https://www.editorialmanager.com/trls","title":"Trials","twitterHandle":"MedicalEvidence","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-7849040/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7849040/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe pericapsular nerve group (PENG) block has emerged as a promising motor-sparing regional anesthesia technique for hip surgery. However, its definitive role in reducing postoperative pain and opioid consumption following total hip arthroplasty (THA) remains a matter of debate. This study aims to evaluate the analgesic efficacy of the PENG block with and without a lateral femoral cutaneous nerve (LFCN) block.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis is a prospective, randomized, double-blind, controlled trial conducted at a single academic center. A total of 168 patients undergoing elective primary THA under general anesthesia will be randomly assigned to one of four groups: (1) low-volume PENG + LFCN block; (2) high-volume PENG + LFCN block; (3) high-volume PENG + sham LFCN; (4) sham PENG + sham LFCN. The primary outcome is the numeric rating scale (NRS) pain score at rest four hours postoperatively. Secondary outcomes include opioid consumption, motor strength, sensory block success, incidence of PONV, patient satisfaction, and adverse events.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDiscussion\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis trial will provide evidence on the optimal volume of PENG block and the additive value of LFCN block in multimodal analgesia for THA. Findings may influence future clinical decision-making on regional techniques for motor-sparing analgesia in hip arthroplasty, particularly in the context of “enhanced recovery after surgery”.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eProtocol version: \u003c/strong\u003e1.0, 13 October 2025\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTrial registration: \u003c/strong\u003eGerman Clinical Trials Register (DRKS): DRKS00037861\u003c/p\u003e","manuscriptTitle":"Effect of the Pericapsular Nerve Group (PENG) Block on Postoperative Pain after Elective Total Hip Arthroplasty: study protocol for a randomized, double-blind, 4-arm factorial trial","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-02 10:19:32","doi":"10.21203/rs.3.rs-7849040/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2026-02-02T05:49:44+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-01-29T11:35:12+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-11-07T11:19:35+00:00","index":"","fulltext":""},{"type":"submitted","content":"Trials","date":"2025-11-07T03:41:01+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"trials","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"trls","sideBox":"Learn more about [Trials](http://trialsjournal.biomedcentral.com/)","snPcode":"13063","submissionUrl":"https://www.editorialmanager.com/trls","title":"Trials","twitterHandle":"MedicalEvidence","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"a045a1c9-2e17-4559-8d6c-cb423cf69c26","owner":[],"postedDate":"February 2nd, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-02-02T10:19:33+00:00","versionOfRecord":[],"versionCreatedAt":"2026-02-02 10:19:32","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7849040","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7849040","identity":"rs-7849040","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}