Efficacy Of High Volume Pericapsular Nerve Group Block in Patients with Acetabular Fracture for Positioning for Subarachnoid Block: A Pilot Study

Efficacy Of High Volume Pericapsular Nerve Group Block in Patients with Acetabular Fracture for Positioning for Subarachnoid Block: A Pilot Study | 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 Efficacy Of High Volume Pericapsular Nerve Group Block in Patients with Acetabular Fracture for Positioning for Subarachnoid Block: A Pilot Study Akhil M S, Vanlal Darlong, Dalim Kumar Baidya, Samarth Mittal, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7971352/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 13 You are reading this latest preprint version Abstract Background: Positioning the patients with acetabular fracture surgeries for neuraxial anesthesia is extremely painful and systemic opioids have limited efficacy. High volume pericapsular nerve group (PENG) block is known to provide a good analgesia for pain around hip but has not been investigated for fracture acetabulum. The aim of the present study was to evaluate the efficacy of high-volume PENG block in improving analgesia and enabling patient positioning for subarachnoid block. Methods: We conducted a prospective single group interventional pilot study in level 1 trauma center in Northern India. Patients between 18 and 75 years of age and ASA physical status of 1 or 2 were enrolled with acetabular fracture scheduled for open reduction and internal fixation (anterior approach) surgery. We assessed numerical rating scale (NRS) score for pain at supine and sitting position and the maximum sitting angle before and 30 minutes after administration of 30ml PENG block. Any need for rescue analgesia and assistance for maintaining the position were noted. Results: A total of 14 patients were recruited. There was a significant decrease in NRS score before and after intervention (supine mean NRS score before vs after block: 3.85±1.4 vs 0.5±0.85, p <0.001; sitting mean NRS score before vs after block: 7.64±1.33 vs 2.21±1.62, p <0.001) along with significant improvement in sitting angle (before vs after block: 35.35 0 ±8.42 0 vs 87.85º±4.25, p <0.001). Conclusions : High-volume PENG block significantly reduces pain scores and increases sitting angle during positioning for neuraxial anesthesia in patients with acetabular fracture. Study was registered on 06/10/2021 in the clinical trial registry of India (www.ctri.nic.in) with unique ID number: CTRI/2021/10/037143. High-volume PENG block (pericapsular nerve group block) acetabular fracture Neuraxial anesthesia. Figures Figure 1 Figure 2 Figure 3 Introduction Fractures of the acetabulum are usually seen in trauma following high-impact injuries like motor vehicle accidents. The primary line of treatment is early fixation of the fracture and mobilization. Procedures for their fixation are done under regional anesthesia (subarachnoid block or combined spinal epidural anesthesia), general anesthesia or a combination of both. The risk and benefits of regional and general anesthesia for lower limb and hip surgeries are more compelling in favor of regional anesthesia. But in acetabular fracture, positioning of the patient is challenging due to extreme pain as neuraxial block is usually performed in sitting (sitting angle 80 0 -90 0 ) or lateral decubitus position. Conventionally, intravenous opioids have been used for pain control during positioning with limited efficacy. The acetabulum has rich sensory innervation from the femoral nerve, obturator nerve, accessory obturator nerve and articular branches of sacral plexus nerves. Anterior hip capsule is richly innervated by articular branches from femoral nerve (FN), obturator nerve (ON), accessory obturator nerve (AON) and branches from lateral cutaneous nerve of thigh. Anterior section of capsule contains both mechano receptors and nociceptive receptors. The posterior part of capsule is innervated by articular branches of sacral plexus which include sciatic nerve, nerve to quadratus femoris, superior gluteal nerve and inferior gluteal nerve. Nociceptive receptors were reported to be rarely present in the posterior capsule based on histological staining evidence. However, it has been postulated that the activation of silent nociceptors in the posterior hip joint capsule during pathological states may account for a painful response, as evidenced by pain relief after posterior hip pericapsular neurolysis( 1 ). A number of regional techniques such as fascia iliaca block (FIB) and femoral nerve block (FNB) are found to be effective for perioperative analgesia and in positioning for neuraxial block with no significant complications for hip bone fractures, but having multiple articular branches from different nerves make these individual blocks inefficient during acetabulum fracture. Pericapsular nerve group (PENG) block is a technique that provides good analgesia with motor sparing benefits in fracture hip by depositing about 20ml of local anesthetic drug( 2 , 3 ). It is found to block the articular branches of femoral nerve, obturator nerve and accessory obturator nerve which covers only the nerve supply to the anterior segment of the hip capsule i.e, posterior capsule is spared. So, their efficacy in acetabular fracture, where it involves pain from both anterior and posterior capsule is inconclusive. But there are case reports which suggest high volume PENG block with 30ml of local anesthetic drug provides a good analgesia in fracture acetabulum( 4 – 6 ). Unlike other hip fractures, there is a paucity of studies for pain management in acetabular fractures. Therefore, this prospective interventional single group pilot study was planned to assess the efficacy of high-volume PENG block to provide analgesia for optimum positioning of the patients with acetabular fracture for neuraxial anesthesia. Primary outcome of our study was NRS score at sitting position for SAB block after administering high volume PENG block. Secondary outcomes were the quality of positioning for spinal anesthesia, degree of angulation of sitting for SAB block and rescue analgesic requirement for sitting for SAB after receiving high-volume PENG block. We hypothesized that high volume PENG block will improve the sitting angle of patient during positioning for neuraxial block by providing good analgesia. Methods Study design, setting and population: We conducted a prospective interventional pilot study at a level 1 trauma center in north India. Patients were recruited between October 2021 and December 2022. Inclusion criteria were adult patients aged 18 – 75 years, body weight ≥50kg, belonging to American Society of Anesthesiologists (ASA) physical status I and II, with acetabular fracture scheduled for open reduction and internal fixation by anterior surgical approach (since posterior surgical approach required prone positioning/ lateral positioning which favored general anesthesia.). Exclusion criteria included patient’s refusal to participate in the study, history of allergy to any of the study drugs, any contraindication to regional anesthesia (spinal abnormalities, infection at the site of injection, coagulopathies), raised intracranial pressure and posterior surgical approach. Ethics and Registration: Institutional ethics committee approval was obtained (IECPG-472/25.08.2021, RT-14/23.09.2021) and the study was registered on 06/10/2021 in the clinical trial registry of India (www.ctri.nic.in; CTRI/2021/10/037143). The study was conducted in accordance with the good clinical practice guidelines and the declaration of Helsinki 2013. Study Protocol: A detailed preanesthetic evaluation was performed. In the operating room, surgical safety checklist was followed, standard ASA monitoring (pulse oximeter, non-invasive blood pressure, electrocardiography) was attached and intravenous access was obtained. Pain was assessed in supine position by numerical rating scale (NRS) score. The patients were instructed to position for spinal anesthesia by sitting as erect as possible without assistance (if required; assistance was provided, as these patients mostly had polytrauma), till they experienced a NRS score of ≥ 5. The maximum NRS score at sitting, the sitting angle and the quality of positioning for spinal anesthesia were noted. Thereafter, high volume PENG block was administered under ultrasound guidance and 30 minutes after the block, the patient was asked to sit again for spinal anesthesia as erect as possible till they experienced a NRS score of ≥ 5. The maximum NRS score for pain in supine and best sitting position, sitting angle and the quality of positioning were documented again. In case of failure to achieve adequate positioning due to pain (NRS score ≥ 5) in spite of high-volume PENG block, intravenous Fentanyl 0.5mcg/Kg of body weight up to a maximum of 2mcg/Kg was injected as rescue analgesia. In case rescue analgesia failed, plan for spinal anesthesia was abandoned and the general anesthesia was administered. All the blocks were performed by experienced consultant anesthesiologists who were not present during pre and post intervention outcome assessment. An independent anesthesiologist who was not part of the study, rated the quality of positioning for spinal anesthesia. A dedicated investigator collected all the data. Ultrasound guided High volume Pericapsular nerve group block procedure: Block was performed with the patient in supine position with hip extended, using a low frequency (2-5 MHz) curvilinear ultrasound probe (Sonosite S-Nerve, FUJIFILM SonoSite, Inc., USA). Probe was initially placed over the anterior inferior iliac spine (AIIS) in a transverse plane, then rotated counterclockwise parallel to the pubic ramus to obtain a short-axis view of iliopsoas muscle and tendon lying on the pubic ramus adjacent to the ilio-pubic eminence (Figure 1). A 21G, 10 cm, blunt tip block needle [(Echoplex+) with echogenic coating right to the tip] was inserted from lateral to medial direction using in-line technique after infiltration of skin with 1-3ml of 2% plain lignocaine. The tip of the block needle was placed in the musculofascial plane between the psoas tendon and ilio-pubic ramus. Following intermittent negative aspiration and constant ultrasound surveillance for adequate fluid spread, local anesthetic solution (15ml of 0.5% bupivacaine + 15ml of 2% plain lignocaine; total 30ml) was injected in 3 ml increments. Following data were collected for each patient: i) baseline data: demographic parameters and baseline variables ii) outcome data: pre and post intervention supine NRS, sitting NRS, maximum sitting angle, any rescue analgesia and rating for the quality of positioning for spinal block. NRS score: NRS consists of a straight line ranging from 0 to 10 with end points defining extreme limits such as 0 indicates no pain and 10 indicates the worst possible pain . Patients were asked to report their pain based on this scale. Sitting angle: Both baseline and post-intervention sitting angles were measured and noted objectively using goniometer (Figure 2) at the best position achieved by the patient. The angle formed by the horizontal line between greater trochanter and lateral femoral epicondyle and vertical line aligning with the mid axillary line was taken as the sitting angle (Figure 3). Patient lying supine indicated a sitting angle of 0° and a patient sitting upright indicated a sitting angle of 90°. Patients were instructed to sit as erect as possible till he/she experienced a pain of NRS score ≥5. Quality of positioning: An independent Anesthesiologist who performed neuraxial block provided a rating score for the quality of patient positioning as 0 (Not satisfactory), 1 (Satisfactory), 2 (Good) and 3 (Optimal). Sample size calculation and Data analysis From our institutional database in acetabular fracture patients, the mean NRS score at sitting for the subarachnoid block was 7.4 ± 2.1. We presumed that the application of the high-volume PENG block would reduce the NRS score at sitting to 4. With an alpha error of 0.05 and power of 90%, 12 patients were required. Considering a drop out of 10%, we planned to recruit at least 14 patients. All the collected data were entered in a Microsoft Excel spreadsheet. Data was represented as Mean ± Standard deviation or in frequency (%). Quantitative data were compared by Student paired t test. A p-value of <0.05 was considered significant Results Data were available for total n = 14 patients who underwent elective acetabular fracture surgery (in anterior approach) under neuraxial anesthesia. The baseline variables are presented in Table 1 . Table 1 Baseline and Demographic characteristics (N = 14) Variable Mean ± SD or N (%) Age (years) 43.2 ± 13.7 Gender Male 13 (92.8%) Female 1 (7.1%) Weight (Kilogram) 70.5 ± 8.8 Height (cm) 169 ± 5.98 BMI (Kg/m²) 24.47 ± 1.94 ASA status ASA I 7 (50%) ASA II 7 (50%) Side of Acetabulum fracture Right 4 (28.57%) Left 10 (71.42%) Duration of surgery (min) 138.2 ± 29.55 Duration of anesthesia (min) 196.07 ± 30.07 BMI, Body Mass Index; ASA, American Society of Anesthesiologists; min: minutes Following the administration of high-volume PENG block, there was a significant decrease in NRS score for pain in supine and sitting position and significant increase in sitting angle (Table 2 ). Only one patient had unsatisfactory position for spinal anesthesia after high-volume PENG block and required rescue fentanyl administration (intravenous fentanyl 40 + 40 mcg) which reduced the patient’s pain to < 5in NRS scale while sitting and neuraxial anesthesia was administered. Table 2 Outcome variables (N = 14) Parameters Baseline (Median [IQR]) Post intervention (Median [IQR]) p-value Supine NRS 4.0 [1.0] 0.0 [1.0] < 0.001 Sitting NRS 7.0 [2.0] 2.0 [1.5] < 0.001 Sitting angle 35.0° [10.0] 90.0° [0.0] < 0.001 Quality of positioning (Not satisfactory/ satisfactory/good/optimal) 14/0/0/0 1/0/0/13 Paired t test; IRQ, Inter quartile range; NRS, Numerical rating scale Discussion Pelvic fractures involve fracture of bones like ilium, ischium, pubis or the socket like acetabulum. Pelvis is innervated with lumbosacral plexus of nerves extensively, which makes the pelvic fractures very painful. In this prospective study, we observed that in acetabular fracture patients, high-volume PENG block provides good analgesia at supine and sitting positions, which improves sitting angle and enables patients to sit satisfactorily for neuraxial anesthesia. Neuraxial anesthesia is the preferred technique for acetabular fracture surgery, as it provides excellent analgesia, motor block, blunts stress response to surgery by sympatholysis and may also reduce intraoperative blood loss( 7 ). However, proper positioning of the patient for a successful neuraxial block is often challenging or impossible due to significant pain. Intravenous opioids are often inadequate and associated with side effects. However, high volume PENG blocks were reported to provide good analgesia in patients with fracture acetabulum ( 5 , 6 ). The current study has demonstrated the analgesic efficacy of this block in the pre-neuraxial period and optimum positioning of the patient. The large improvement in pain scores and sitting angle could be due to a wide distribution of the local anesthetic drug which ultimately blocked all the nerves in the affected area leading to an excellent analgesia. Pericapsular nerve group (PENG) block is a technique that provide good analgesia with motor sparing benefits in fracture hip by depositing about 20ml of local anesthetics( 2 , 3 ). However, PENG block covers only the nerve supply to the anterior segment of the hip capsule and posterior capsule is spared. So, their efficacy in acetabular fractures is not known. Ciftci et al conducted a cadaveric study to demonstrate drug spread using 20 and 30 ml of drug in PENG block. There was dye spread till below the tensor fascia lata with the 20 ml volume (covers femoral nerve and accessory obturator nerve). There was dye spread throughout iliopsoas, around the vastus medialis, and gluteus medius muscles with the 30ml volume of drug- high volume PENG block (covers femoral nerve, lateral femoral cutaneous nerve, obturator nerve, accessory obturator nerve)( 8 ). Ece Yamak Altinpulluk et al, in his cadaveric study, showed that a high-volume PENG block (30 ml dye) resulted in extensive drug spread in the hip joint anteriorly and posteriorly (articular branches of sacral plexus innervate posterior capsule of hip joint)( 9 ). Bora Bilal et al reported good post-operative analgesia with high volume PENG block in two patients with acetabular fracture repair( 5 ). In case reports available with high volume PENG block given in acetabular patients, the drug for local anesthetic used were 30ml of either 0.25% bupivacaine or 0.2% ropivacaine with dexamethasone as additive( 10 ). The effect of the block was achieved by 30min. In our study we combined 15ml of 0.5% bupivacaine with 15ml of 2% lignocaine and the effect of the block was observed early and maximum analgesia could be achieved by 30min. However, it is important to wait for almost 30 minutes between the administration of the block and positioning of the patient. In most of the case studies with high volume PENG block, patients received maximum pain relief by 30 minutes( 5 , 6 ). Although, the time of onset and maximum block effect were not included in our study parameters, most of the patients self-reported significant pain relief in supine position within 15 to 20 minutes of block placement. In spite of good pain relief, many patients may require assistance to position themselves for spinal anesthesia. All the patients in this study had polytrauma following road traffic accidents and required assistance for positioning. However, after attaining a proper sitting position, they did not require any assistance for maintaining the angulation. Only one (7.2%) patient had a non-satisfactory position due to pain (NRS score 5), and required intravenous fentanyl (40 + 40mcg two boluses) and continuous assistance for positioning. We did not notice any kind of complications or drug side effects during and after the block procedures and also during intraoperative and postoperative period. The dose of the drug should be carefully calculated as it is a high-volume block and drug should be injected in aliquots only under ultrasound guidance. The limitations of the current study could be a small sample [since incidence of acetabular fractures are relatively rare accounting for 1.5% of all adult fractures( 11 )], lack of serial monitoring of pain scores to find out the earliest time of pain relief after block placement, any effect of the block on intraoperative and post-operative analgesia and sensory block in the distribution of femoral and obturator nerves were not observed. A further randomized trial with a larger sample size may provide better quality of evidence. Even though there are some case series reported to have pain relief after high-volume PENG block in acetabular fracture patients( 5 , 8 ); to the best of our knowledge, this is the first study assessing efficacy of high-volume PENG block for positioning of patients with acetabular fracture for neuraxial anesthesia. Moreover, a robust protocol of block placement and data collection by an independent investigator could minimize biases and add to the strength of the study. To conclude, high-volume PENG block improves analgesia and enables patients with acetabular fractures to sit in a position that allows for giving neuraxial anesthesia. Abbreviations PENG block, pericapsular nerve group block; ASA, American Society of Anesthesiologists; NRS, Numerical rating scale; FN, Femoral nerve; ON, Obturator nerve; AON, Accessory obturator nerve; FIB, Fascia iliaca block; FNB, Femoral nerve block; SAB, Subarachnoid block; AIIS, anterior inferior iliac spine. Declarations Human Ethics Committee approval : Institute Ethics Committee, All India Institute of Medical Sciences. IECPG-472/25.08.2021,RT-14/23.09.2021 Trial registration: Clinical Trials Registry of India (www.ctri.nic.in; CTRI/2021/10/037143). Trial registration Date: 06/10/2021 Consent to participate : Consent that was obtained from all of the participants was informed. Consent for Publication: Not Applicable. Availability of data and materials: Individual deidentified participant data (including data dictionaries) will be shared. Data, in particular (de-identified demographic data and observed patient parameters), will be shared. Additionally, related documents will also be available (e.g., study protocol, statistical analysis); the data will become available beginning 3 months after article publication and ending 36 months after publication. The data will be provided for individual participant data meta-analysis. Proposals may be submitted up to 36 months following article publication. Data will be available during the mentioned period upon request from the email ID: [email protected] . Competing interests: Not applicable Prior presentation: Not applicable Funding information: Not applicable Author’s Contributions: Prof. Vanlal Darlong: Corresponding author Dr. Akhil.M.S: First Author Prof. Dalim Kumar Baidya, Dr. Samarth Mittal, Prof. Vivek Trikha, Prof. R.K. Pandey, Prof. Renu Sinha, Prof. Jyotsna Punj , Prof. Chhavi Sawhney: Manuscript review and editing. Acknowledgements: Nil References Pun M, Ng T, Vermeylen K, Tran J. Innervation of the hip joint: implications for regional anaesthesia and image-guided interventional pain procedures. BJA Educ. 2024 June;24(6):191–202. Morrison C, Brown B, Lin DY, Jaarsma R, Kroon H. Analgesia and anesthesia using the pericapsular nerve group block in hip surgery and hip fracture: a scoping review. Reg Anesth Pain Med. 2021 Feb;46(2):169–75. Kukreja P, Avila A, Northern T, Dangle J, Kolli S, Kalagara H. A Retrospective Case Series of Pericapsular Nerve Group (PENG) Block for Primary Versus Revision Total Hip Arthroplasty Analgesia. Cureus. 2020 May 19;12(5):e8200. Ritcey B, Pageau P, Woo MY, Perry JJ. Regional Nerve Blocks For Hip and Femoral Neck Fractures in the Emergency Department: A Systematic Review. CJEM. 2016 Jan;18(1):37–47. Bilal B, Öksüz G, Boran ÖF, Topak D, Doğar F. High volume pericapsular nerve group (PENG) block for acetabular fracture surgery: A new horizon for novel block. J Clin Anesth. 2020 June;62:109702. Luftig J, Dreyfuss A, Mantuani D, Howell K, White A, Nagdev A. A new frontier in pelvic fracture pain control in the ED: Successful use of the pericapsular nerve group (PENG) block. Am J Emerg Med. 2020 Dec;38(12):2761.e5-2761.e9. Dauphin A, Raymer KE, Stanton EB, Fuller HD. Comparison of general anesthesia with and without lumbar epidural for total hip arthroplasty: effects of epidural block on hip arthroplasty. J Clin Anesth. 1997 May;9(3):200–3. Ciftci B, Ahiskalioglu A, Altintas HM, Tekin B, Sakul BU, Alici HA. A possible mechanism of motor blockade of high volume pericapsular nerve group (PENG) block: A cadaveric study. J Clin Anesth. 2021 Nov;74:110407. Yamak Altinpulluk E, Galluccio F, Salazar C, Espinoza K, Olea MS, Hochberg U, et al. Peng block in prosthetic hip replacement: A cadaveric radiological evaluation. J Clin Anesth. 2020 Oct;65:109888. Mistry T, Sonawane K, Raghuvanshi A, Balavenkatasubramanian J, Gurumoorthi P. Preemptive pericapsular nerve group block to facilitate sitting position for neuraxial anesthesia in patients with acetabular fractures: A case series. Saudi J Anaesth. 2022;16(2):221–5. Sen RK, Trikha V, Meena U, Perumal R, Tripathy SK, Mahesh M, et al. Acetabular fracture in India: An epidemiological study. J Clin Orthop Trauma. 2024 Sept;56:102540. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 09 Feb, 2026 Reviews received at journal 21 Dec, 2025 Reviews received at journal 21 Dec, 2025 Reviewers agreed at journal 21 Dec, 2025 Reviews received at journal 15 Dec, 2025 Reviewers agreed at journal 13 Dec, 2025 Reviewers agreed at journal 12 Dec, 2025 Reviewers agreed at journal 04 Dec, 2025 Reviewers invited by journal 04 Dec, 2025 Editor assigned by journal 01 Dec, 2025 Editor invited by journal 12 Nov, 2025 Submission checks completed at journal 11 Nov, 2025 First submitted to journal 11 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. 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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-7971352","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":555374936,"identity":"6f2621e3-784d-49ce-94b5-ccc9bbe902dd","order_by":0,"name":"Akhil M S","email":"","orcid":"","institution":"All India Institute of Medical Sciences","correspondingAuthor":false,"prefix":"","firstName":"Akhil","middleName":"M","lastName":"S","suffix":""},{"id":555374939,"identity":"3a8683d3-2c37-4747-b88c-35fd52f11507","order_by":1,"name":"Vanlal Darlong","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA0UlEQVRIiWNgGAWjYBACewYGxgMgBj8DAxtxWgwbGBjAWiQbiNVicACqBcggVsvxsw8OfNxRm7j5RvKzBx8qGOT5xQ4Q0HIm3eDgzDPHE7fdSDM3nHGGwXDm7ARCDktjOMzbdszY7EaCmTRvG0OCwW1CWs4/g2gxnpH+jUgtN8C21MgZSOQQaYvhjGcMB2e2HZCTOPOmTHLGGQnCfrHnT2N88LGtjoe/PX2bxIcKG3l+aQJaoOAwA4MAWKUEUcpBoA6YYg4QrXoUjIJRMApGGAAALPFH6JK2FogAAAAASUVORK5CYII=","orcid":"","institution":"All India Institute of Medical Sciences","correspondingAuthor":true,"prefix":"","firstName":"Vanlal","middleName":"","lastName":"Darlong","suffix":""},{"id":555374941,"identity":"972c25f6-42cd-494a-963f-1844440efa81","order_by":2,"name":"Dalim Kumar Baidya","email":"","orcid":"","institution":"All India Institute of Medical Sciences","correspondingAuthor":false,"prefix":"","firstName":"Dalim","middleName":"Kumar","lastName":"Baidya","suffix":""},{"id":555374944,"identity":"cd31442b-79be-4557-b54e-53a518de81dd","order_by":3,"name":"Samarth Mittal","email":"","orcid":"","institution":"All India Institute of Medical Sciences","correspondingAuthor":false,"prefix":"","firstName":"Samarth","middleName":"","lastName":"Mittal","suffix":""},{"id":555374948,"identity":"0af1a10f-2db3-472b-82db-748f7e89a4e8","order_by":4,"name":"Vivek Trikha","email":"","orcid":"","institution":"All India Institute of Medical Sciences","correspondingAuthor":false,"prefix":"","firstName":"Vivek","middleName":"","lastName":"Trikha","suffix":""},{"id":555374949,"identity":"0ce7d820-97b5-45b7-beeb-038fa9c94974","order_by":5,"name":"R. 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11:43:18","extension":"html","order_by":11,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":64257,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7971352/v1/602028aa80cc03c91062f060.html"},{"id":97892924,"identity":"4211fd4d-672d-446c-aaee-a3b61925e852","added_by":"auto","created_at":"2025-12-10 15:24:15","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":202970,"visible":true,"origin":"","legend":"\u003cp\u003eSono-anatomy of high-volume PENG block. Psoas tendon pushed upward is a reliable sign of adequate drug spread. AIIS, anterior inferior iliac spine; IPE, ilio-pubic eminence; PT, psoas tendon; IM, Iliacus muscle; PM, psoas muscle; FA, femoral artery; FV, femoral vein\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7971352/v1/5c197849157474be4165f1fc.png"},{"id":97697447,"identity":"54d6dc49-0cd4-49ef-9607-e2b3e6f40466","added_by":"auto","created_at":"2025-12-08 11:43:18","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":110449,"visible":true,"origin":"","legend":"\u003cp\u003eGoniometer\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7971352/v1/86544cce77d053b0035f701b.png"},{"id":97697444,"identity":"f3b697a2-49be-49b7-bb5c-91228fcd6510","added_by":"auto","created_at":"2025-12-08 11:43:18","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":516612,"visible":true,"origin":"","legend":"\u003cp\u003eSitting angle measurement using a simple goniometer. A: before intervention; B- after intervention.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-7971352/v1/8a6625a41835e45b157e0682.png"},{"id":98420789,"identity":"4765c4dc-fe8a-4f9f-9265-85b9b65cf958","added_by":"auto","created_at":"2025-12-17 16:07:06","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1572570,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7971352/v1/3d4a3b09-65ef-46c6-8fba-65eccb77828d.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Efficacy Of High Volume Pericapsular Nerve Group Block in Patients with Acetabular Fracture for Positioning for Subarachnoid Block: A Pilot Study","fulltext":[{"header":"Introduction","content":"\u003cp\u003eFractures of the acetabulum are usually seen in trauma following high-impact injuries like motor vehicle accidents. The primary line of treatment is early fixation of the fracture and mobilization. Procedures for their fixation are done under regional anesthesia (subarachnoid block or combined spinal epidural anesthesia), general anesthesia or a combination of both. The risk and benefits of regional and general anesthesia for lower limb and hip surgeries are more compelling in favor of regional anesthesia. But in acetabular fracture, positioning of the patient is challenging due to extreme pain as neuraxial block is usually performed in sitting (sitting angle 80\u003csup\u003e0\u003c/sup\u003e-90\u003csup\u003e0\u003c/sup\u003e) or lateral decubitus position. Conventionally, intravenous opioids have been used for pain control during positioning with limited efficacy.\u003c/p\u003e\u003cp\u003eThe acetabulum has rich sensory innervation from the femoral nerve, obturator nerve, accessory obturator nerve and articular branches of sacral plexus nerves. Anterior hip capsule is richly innervated by articular branches from femoral nerve (FN), obturator nerve (ON), accessory obturator nerve (AON) and branches from lateral cutaneous nerve of thigh. Anterior section of capsule contains both mechano receptors and nociceptive receptors. The posterior part of capsule is innervated by articular branches of sacral plexus which include sciatic nerve, nerve to quadratus femoris, superior gluteal nerve and inferior gluteal nerve. Nociceptive receptors were reported to be rarely present in the posterior capsule based on histological staining evidence. However, it has been postulated that the activation of silent nociceptors in the posterior hip joint capsule during pathological states may account for a painful response, as evidenced by pain relief after posterior hip pericapsular neurolysis(\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eA number of regional techniques such as fascia iliaca block (FIB) and femoral nerve block (FNB) are found to be effective for perioperative analgesia and in positioning for neuraxial block with no significant complications for hip bone fractures, but having multiple articular branches from different nerves make these individual blocks inefficient during acetabulum fracture.\u003c/p\u003e\u003cp\u003ePericapsular nerve group (PENG) block is a technique that provides good analgesia with motor sparing benefits in fracture hip by depositing about 20ml of local anesthetic drug(\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e). It is found to block the articular branches of femoral nerve, obturator nerve and accessory obturator nerve which covers only the nerve supply to the anterior segment of the hip capsule i.e, posterior capsule is spared. So, their efficacy in acetabular fracture, where it involves pain from both anterior and posterior capsule is inconclusive. But there are case reports which suggest high volume PENG block with 30ml of local anesthetic drug provides a good analgesia in fracture acetabulum(\u003cspan additionalcitationids=\"CR5\" citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eUnlike other hip fractures, there is a paucity of studies for pain management in acetabular fractures. Therefore, this prospective interventional single group pilot study was planned to assess the efficacy of high-volume PENG block to provide analgesia for optimum positioning of the patients with acetabular fracture for neuraxial anesthesia. Primary outcome of our study was NRS score at sitting position for SAB block after administering high volume PENG block. Secondary outcomes were the quality of positioning for spinal anesthesia, degree of angulation of sitting for SAB block and rescue analgesic requirement for sitting for SAB after receiving high-volume PENG block.\u003c/p\u003e\u003cp\u003eWe hypothesized that high volume PENG block will improve the sitting angle of patient during positioning for neuraxial block by providing good analgesia.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e\u003cem\u003eStudy design, setting and population:\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eWe conducted a prospective interventional pilot study at a level 1 trauma center in north India. Patients were recruited between October 2021 and December 2022. Inclusion criteria were adult patients aged 18 \u0026ndash; 75 years, body weight \u0026ge;50kg, belonging to American Society of Anesthesiologists (ASA) physical status I and II, with acetabular fracture scheduled for open reduction and internal fixation by anterior surgical approach (since posterior surgical approach required prone positioning/ lateral positioning which favored general anesthesia.). Exclusion criteria included patient\u0026rsquo;s refusal to participate in the study, history of allergy to any of the study drugs, any contraindication to regional anesthesia (spinal abnormalities, infection at the site of injection, coagulopathies), raised intracranial pressure and posterior surgical approach.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eEthics and Registration:\u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eInstitutional ethics committee approval was obtained (IECPG-472/25.08.2021, RT-14/23.09.2021) and the study was registered on 06/10/2021 in the clinical trial registry of India (www.ctri.nic.in; CTRI/2021/10/037143). The study was conducted in accordance with the good clinical practice guidelines and the declaration of Helsinki 2013.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eStudy Protocol:\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eA detailed preanesthetic evaluation was performed. In the operating room, surgical safety checklist was followed, standard ASA monitoring (pulse oximeter, non-invasive blood pressure, electrocardiography) was attached and intravenous access was obtained.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003ePain was assessed in supine position by numerical rating scale (NRS) score. The patients were instructed to position for spinal anesthesia by sitting as erect as possible without assistance (if required; assistance was provided, as these patients mostly had polytrauma), till they experienced a NRS score of \u0026ge; 5. The maximum NRS score at sitting, the sitting angle and the quality of positioning for spinal anesthesia were noted.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThereafter, high volume PENG block was administered under ultrasound guidance and 30 minutes after the block, the patient was asked to sit again for spinal anesthesia as erect as possible till they experienced a NRS score of \u0026ge; 5. The maximum NRS score for pain in supine and best sitting position, sitting angle and the quality of positioning were documented again. In case of failure to achieve adequate positioning due to pain (NRS score \u0026ge; 5) in spite of high-volume PENG block, intravenous Fentanyl 0.5mcg/Kg of body weight up to a maximum of 2mcg/Kg was injected as rescue analgesia. In case rescue analgesia failed, plan for spinal anesthesia was abandoned and the general anesthesia was administered.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAll the blocks were performed by experienced consultant anesthesiologists who were not present during pre and post intervention outcome assessment. An independent anesthesiologist who was not part of the study, rated the quality of positioning for spinal anesthesia. A dedicated investigator collected all the data.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eUltrasound guided High volume Pericapsular nerve group block procedure:\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eBlock was performed with the patient in supine position with hip extended, using a low frequency (2-5 MHz) curvilinear ultrasound probe (Sonosite S-Nerve, FUJIFILM SonoSite, Inc., USA). Probe was initially placed over the anterior inferior iliac spine (AIIS) in a transverse plane, then rotated counterclockwise parallel to the pubic ramus to obtain a short-axis view of iliopsoas muscle and tendon lying on the pubic ramus adjacent to the ilio-pubic eminence (Figure 1). A 21G, 10 cm, blunt tip block needle [(Echoplex+) with echogenic coating right to the tip] was inserted from lateral to medial direction using in-line technique after infiltration of skin with 1-3ml of 2% plain lignocaine. The tip of the block needle was placed in the musculofascial plane between the psoas tendon and ilio-pubic ramus. Following intermittent negative aspiration and constant ultrasound surveillance for adequate fluid spread, local anesthetic solution (15ml of 0.5% bupivacaine + 15ml of 2% plain lignocaine; total 30ml) was injected in 3 ml increments.\u003c/p\u003e\n\u003cp\u003eFollowing data were collected for each patient: i) baseline data: demographic parameters and baseline variables ii) outcome data: pre and post intervention supine NRS, sitting NRS, maximum sitting angle, any rescue analgesia and rating for the quality of positioning for spinal block.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eNRS score: NRS consists of a straight line ranging from 0 to 10 with end points defining extreme limits such as 0 indicates no pain and 10 indicates the worst possible pain\u003cstrong\u003e.\u0026nbsp;\u003c/strong\u003ePatients were asked to report their pain based on this scale.\u003c/p\u003e\n\u003cp\u003eSitting angle: Both baseline and post-intervention sitting angles were measured and noted objectively using goniometer (Figure 2) at the best position achieved by the patient. The angle formed by the horizontal line between greater trochanter and lateral femoral epicondyle and vertical line aligning with the mid axillary line was taken as the sitting angle (Figure 3). Patient lying supine indicated a sitting angle of 0\u0026deg; and a patient sitting upright indicated a sitting angle of 90\u0026deg;. Patients were instructed to sit as erect as possible till he/she experienced a pain of NRS score \u0026ge;5.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eQuality of positioning: An independent Anesthesiologist who performed neuraxial block provided a rating score for the quality of patient positioning as 0 (Not satisfactory), 1 (Satisfactory), 2 (Good) and 3 (Optimal).\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eSample size calculation and Data analysis\u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eFrom our institutional database in acetabular fracture patients, the mean NRS score at sitting for the subarachnoid block was 7.4 \u0026plusmn; 2.1. We presumed that the application of the high-volume PENG block would reduce the NRS score at sitting to 4. With an alpha error of 0.05 and power of 90%, 12 patients were required. Considering a drop out of 10%, we planned to recruit at least 14 patients. All the collected data were entered in a Microsoft Excel spreadsheet. Data was represented as Mean \u0026plusmn; Standard deviation or in frequency (%). Quantitative data were compared by Student paired t test. A p-value of \u0026lt;0.05 was considered significant\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eData were available for total n\u0026thinsp;=\u0026thinsp;14 patients who underwent elective acetabular fracture surgery (in anterior approach) under neuraxial anesthesia. The baseline variables are presented in Table \u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eBaseline and Demographic characteristics (N\u0026thinsp;=\u0026thinsp;14)\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"3\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eVariable\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD or N (%)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eAge (years)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e43.2\u0026thinsp;\u0026plusmn;\u0026thinsp;13.7\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eGender\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMale\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e13 (92.8%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFemale\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1 (7.1%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eWeight (Kilogram)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e70.5\u0026thinsp;\u0026plusmn;\u0026thinsp;8.8\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eHeight (cm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e169\u0026thinsp;\u0026plusmn;\u0026thinsp;5.98\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eBMI (Kg/m\u0026sup2;)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e24.47\u0026thinsp;\u0026plusmn;\u0026thinsp;1.94\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eASA status\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eASA I\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e7 (50%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eASA II\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e7 (50%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eSide of Acetabulum fracture\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRight\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4 (28.57%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eLeft\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e10 (71.42%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eDuration of surgery (min)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e138.2\u0026thinsp;\u0026plusmn;\u0026thinsp;29.55\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eDuration of anesthesia (min)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e196.07\u0026thinsp;\u0026plusmn;\u0026thinsp;30.07\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"3\"\u003eBMI, Body Mass Index; ASA, American Society of Anesthesiologists; min: minutes\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eFollowing the administration of high-volume PENG block, there was a significant decrease in NRS score for pain in supine and sitting position and significant increase in sitting angle (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Only one patient had unsatisfactory position for spinal anesthesia after high-volume PENG block and required rescue fentanyl administration (intravenous fentanyl 40\u0026thinsp;+\u0026thinsp;40 mcg) which reduced the patient\u0026rsquo;s pain to \u0026lt;\u0026thinsp;5in NRS scale while sitting and neuraxial anesthesia was administered.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eOutcome variables (N\u0026thinsp;=\u0026thinsp;14)\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eParameters\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eBaseline (Median [IQR])\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003ePost intervention\u003c/p\u003e\u003cp\u003e(Median [IQR])\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003ep-value\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSupine NRS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4.0 [1.0]\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.0 [1.0]\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSitting NRS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e7.0 [2.0]\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2.0 [1.5]\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSitting angle\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e35.0\u0026deg; [10.0]\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e90.0\u0026deg; [0.0]\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eQuality of positioning\u003c/p\u003e\u003cp\u003e(Not satisfactory/ satisfactory/good/optimal)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e14/0/0/0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1/0/0/13\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"4\"\u003ePaired t test; IRQ, Inter quartile range; NRS, Numerical rating scale\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003ePelvic fractures involve fracture of bones like ilium, ischium, pubis or the socket like acetabulum. Pelvis is innervated with lumbosacral plexus of nerves extensively, which makes the pelvic fractures very painful.\u003c/p\u003e\u003cp\u003eIn this prospective study, we observed that in acetabular fracture patients, high-volume PENG block provides good analgesia at supine and sitting positions, which improves sitting angle and enables patients to sit satisfactorily for neuraxial anesthesia.\u003c/p\u003e\u003cp\u003eNeuraxial anesthesia is the preferred technique for acetabular fracture surgery, as it provides excellent analgesia, motor block, blunts stress response to surgery by sympatholysis and may also reduce intraoperative blood loss(\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e). However, proper positioning of the patient for a successful neuraxial block is often challenging or impossible due to significant pain. Intravenous opioids are often inadequate and associated with side effects. However, high volume PENG blocks were reported to provide good analgesia in patients with fracture acetabulum (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e). The current study has demonstrated the analgesic efficacy of this block in the pre-neuraxial period and optimum positioning of the patient.\u003c/p\u003e\u003cp\u003eThe large improvement in pain scores and sitting angle could be due to a wide distribution of the local anesthetic drug which ultimately blocked all the nerves in the affected area leading to an excellent analgesia.\u003c/p\u003e\u003cp\u003ePericapsular nerve group (PENG) block is a technique that provide good analgesia with motor sparing benefits in fracture hip by depositing about 20ml of local anesthetics(\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e). However, PENG block covers only the nerve supply to the anterior segment of the hip capsule and posterior capsule is spared. So, their efficacy in acetabular fractures is not known. Ciftci et al conducted a cadaveric study to demonstrate drug spread using 20 and 30 ml of drug in PENG block. There was dye spread till below the tensor fascia lata with the 20 ml volume (covers femoral nerve and accessory obturator nerve). There was dye spread throughout iliopsoas, around the vastus medialis, and gluteus medius muscles with the 30ml volume of drug- high volume PENG block (covers femoral nerve, lateral femoral cutaneous nerve, obturator nerve, accessory obturator nerve)(\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eEce Yamak Altinpulluk et al, in his cadaveric study, showed that a high-volume PENG block (30 ml dye) resulted in extensive drug spread in the hip joint anteriorly and posteriorly (articular branches of sacral plexus innervate posterior capsule of hip joint)(\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e). Bora Bilal et al reported good post-operative analgesia with high volume PENG block in two patients with acetabular fracture repair(\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eIn case reports available with high volume PENG block given in acetabular patients, the drug for local anesthetic used were 30ml of either 0.25% bupivacaine or 0.2% ropivacaine with dexamethasone as additive(\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e). The effect of the block was achieved by 30min. In our study we combined 15ml of 0.5% bupivacaine with 15ml of 2% lignocaine and the effect of the block was observed early and maximum analgesia could be achieved by 30min.\u003c/p\u003e\u003cp\u003eHowever, it is important to wait for almost 30 minutes between the administration of the block and positioning of the patient. In most of the case studies with high volume PENG block, patients received maximum pain relief by 30 minutes(\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e). Although, the time of onset and maximum block effect were not included in our study parameters, most of the patients self-reported significant pain relief in supine position within 15 to 20 minutes of block placement. In spite of good pain relief, many patients may require assistance to position themselves for spinal anesthesia. All the patients in this study had polytrauma following road traffic accidents and required assistance for positioning. However, after attaining a proper sitting position, they did not require any assistance for maintaining the angulation. Only one (7.2%) patient had a non-satisfactory position due to pain (NRS score 5), and required intravenous fentanyl (40\u0026thinsp;+\u0026thinsp;40mcg two boluses) and continuous assistance for positioning.\u003c/p\u003e\u003cp\u003eWe did not notice any kind of complications or drug side effects during and after the block procedures and also during intraoperative and postoperative period. The dose of the drug should be carefully calculated as it is a high-volume block and drug should be injected in aliquots only under ultrasound guidance.\u003c/p\u003e\u003cp\u003eThe limitations of the current study could be a small sample [since incidence of acetabular fractures are relatively rare accounting for 1.5% of all adult fractures(\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e)], lack of serial monitoring of pain scores to find out the earliest time of pain relief after block placement, any effect of the block on intraoperative and post-operative analgesia and sensory block in the distribution of femoral and obturator nerves were not observed. A further randomized trial with a larger sample size may provide better quality of evidence. Even though there are some case series reported to have pain relief after high-volume PENG block in acetabular fracture patients(\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e); to the best of our knowledge, this is the first study assessing efficacy of high-volume PENG block for positioning of patients with acetabular fracture for neuraxial anesthesia. Moreover, a robust protocol of block placement and data collection by an independent investigator could minimize biases and add to the strength of the study.\u003c/p\u003e\u003cp\u003eTo conclude, high-volume PENG block improves analgesia and enables patients with acetabular fractures to sit in a position that allows for giving neuraxial anesthesia.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003ePENG block, pericapsular nerve group block; ASA, American Society of Anesthesiologists; NRS, Numerical rating scale; FN, Femoral nerve; ON, Obturator nerve; AON, Accessory obturator nerve; FIB, Fascia iliaca block; FNB, Femoral nerve block; SAB, Subarachnoid block; AIIS, anterior inferior iliac spine. \u0026nbsp; \u0026nbsp;\u0026nbsp;\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eHuman Ethics Committee approval\u003c/strong\u003e: Institute Ethics Committee, All India Institute of Medical Sciences. IECPG-472/25.08.2021,RT-14/23.09.2021\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTrial registration:\u003c/strong\u003e Clinical Trials Registry of India (www.ctri.nic.in; CTRI/2021/10/037143).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTrial registration Date:\u0026nbsp;\u003c/strong\u003e06/10/2021\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to participate\u003c/strong\u003e: Consent that was obtained from all of the participants was informed.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for Publication:\u0026nbsp;\u003c/strong\u003eNot Applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials:\u0026nbsp;\u003c/strong\u003eIndividual deidentified participant data (including data dictionaries) will be shared. Data, in particular (de-identified demographic data and observed patient parameters), will be shared. Additionally, related documents will also be available (e.g., study protocol, statistical analysis); the data will become available beginning 3 months after article publication and ending 36 months after publication. The data will be provided for individual participant data meta-analysis. Proposals may be submitted up to 36 months following article publication. Data will be available during the mentioned period upon request from the email ID: [email protected].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests:\u0026nbsp;\u003c/strong\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePrior presentation:\u0026nbsp;\u003c/strong\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding information:\u0026nbsp;\u003c/strong\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor\u0026rsquo;s Contributions:\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eProf. Vanlal Darlong: Corresponding author\u003c/p\u003e\n\u003cp\u003eDr. Akhil.M.S: First Author\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eProf. Dalim Kumar Baidya, Dr. Samarth Mittal, Prof. Vivek Trikha, Prof. R.K. Pandey, Prof. Renu Sinha, Prof. Jyotsna Punj\u003csup\u003e,\u003c/sup\u003e Prof. Chhavi Sawhney: Manuscript review and editing.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements:\u0026nbsp;\u003c/strong\u003eNil\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003ePun M, Ng T, Vermeylen K, Tran J. Innervation of the hip joint: implications for regional anaesthesia and image-guided interventional pain procedures. BJA Educ. 2024 June;24(6):191\u0026ndash;202.\u003c/li\u003e\n \u003cli\u003eMorrison C, Brown B, Lin DY, Jaarsma R, Kroon H. Analgesia and anesthesia using the pericapsular nerve group block in hip surgery and hip fracture: a scoping review. Reg Anesth Pain Med. 2021 Feb;46(2):169\u0026ndash;75.\u003c/li\u003e\n \u003cli\u003eKukreja P, Avila A, Northern T, Dangle J, Kolli S, Kalagara H. A Retrospective Case Series of Pericapsular Nerve Group (PENG) Block for Primary Versus Revision Total Hip Arthroplasty Analgesia. Cureus. 2020 May 19;12(5):e8200.\u003c/li\u003e\n \u003cli\u003eRitcey B, Pageau P, Woo MY, Perry JJ. Regional Nerve Blocks For Hip and Femoral Neck Fractures in the Emergency Department: A Systematic Review. CJEM. 2016 Jan;18(1):37\u0026ndash;47.\u003c/li\u003e\n \u003cli\u003eBilal B, \u0026Ouml;ks\u0026uuml;z G, Boran \u0026Ouml;F, Topak D, Doğar F. High volume pericapsular nerve group (PENG) block for acetabular fracture surgery: A new horizon for novel block. J Clin Anesth. 2020 June;62:109702.\u003c/li\u003e\n \u003cli\u003eLuftig J, Dreyfuss A, Mantuani D, Howell K, White A, Nagdev A. A new frontier in pelvic fracture pain control in the ED: Successful use of the pericapsular nerve group (PENG) block. Am J Emerg Med. 2020 Dec;38(12):2761.e5-2761.e9.\u003c/li\u003e\n \u003cli\u003eDauphin A, Raymer KE, Stanton EB, Fuller HD. Comparison of general anesthesia with and without lumbar epidural for total hip arthroplasty: effects of epidural block on hip arthroplasty. J Clin Anesth. 1997 May;9(3):200\u0026ndash;3.\u003c/li\u003e\n \u003cli\u003eCiftci B, Ahiskalioglu A, Altintas HM, Tekin B, Sakul BU, Alici HA. A possible mechanism of motor blockade of high volume pericapsular nerve group (PENG) block: A cadaveric study. J Clin Anesth. 2021 Nov;74:110407.\u003c/li\u003e\n \u003cli\u003eYamak Altinpulluk E, Galluccio F, Salazar C, Espinoza K, Olea MS, Hochberg U, et al. Peng block in prosthetic hip replacement: A cadaveric radiological evaluation. J Clin Anesth. 2020 Oct;65:109888.\u003c/li\u003e\n \u003cli\u003eMistry T, Sonawane K, Raghuvanshi A, Balavenkatasubramanian J, Gurumoorthi P. Preemptive pericapsular nerve group block to facilitate sitting position for neuraxial anesthesia in patients with acetabular fractures: A case series. Saudi J Anaesth. 2022;16(2):221\u0026ndash;5.\u003c/li\u003e\n \u003cli\u003eSen RK, Trikha V, Meena U, Perumal R, Tripathy SK, Mahesh M, et al. Acetabular fracture in India: An epidemiological study. J Clin Orthop Trauma. 2024 Sept;56:102540.\u003c/li\u003e\n\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":"bmc-anesthesiology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bane","sideBox":"Learn more about [BMC Anesthesiology](http://bmcanesthesiol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bane","title":"BMC Anesthesiology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"High-volume PENG block (pericapsular nerve group block), acetabular fracture, Neuraxial anesthesia. ","lastPublishedDoi":"10.21203/rs.3.rs-7971352/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7971352/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground:\u0026nbsp;\u003c/strong\u003ePositioning the patients with acetabular fracture surgeries for neuraxial anesthesia is extremely painful and systemic opioids have limited efficacy. High volume pericapsular nerve group (PENG) block is known to provide a good analgesia for pain around hip but has not been investigated for fracture acetabulum. \u0026nbsp;The aim of the present study was to evaluate the efficacy of high-volume PENG block in improving analgesia and enabling patient positioning for subarachnoid block.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods:\u003c/strong\u003e\u0026nbsp;We conducted a prospective single group interventional pilot study in level 1 trauma center in Northern India. Patients between 18 and 75 years of age and ASA physical status of 1 or 2 were enrolled with acetabular fracture scheduled for open reduction and internal fixation (anterior approach) surgery. We assessed numerical rating scale (NRS) score for pain at supine and sitting position and the maximum sitting angle before and 30 minutes after administration of 30ml PENG block. Any need for rescue analgesia and assistance for maintaining the position were noted.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults:\u003c/strong\u003e\u0026nbsp; A total of 14 patients were recruited. There was a significant decrease in NRS score before and after intervention (supine mean NRS score before vs after block: 3.85±1.4 vs 0.5±0.85, p \u0026lt;0.001; sitting mean NRS score before vs after block: 7.64±1.33 vs 2.21±1.62, p \u0026lt;0.001) along with significant improvement in sitting angle (before vs after block: 35.35\u003csup\u003e0\u003c/sup\u003e±8.42\u003csup\u003e0\u003c/sup\u003e\u0026nbsp;vs 87.85º±4.25, p \u0026lt;0.001).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions\u003c/strong\u003e: High-volume PENG block significantly reduces pain scores and increases sitting angle during positioning for neuraxial anesthesia in patients with acetabular fracture.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eStudy was registered on 06/10/2021 in the clinical trial registry of India (www.ctri.nic.in) with unique ID number: CTRI/2021/10/037143.\u003c/p\u003e","manuscriptTitle":"Efficacy Of High Volume Pericapsular Nerve Group Block in Patients with Acetabular Fracture for Positioning for Subarachnoid Block: A Pilot Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-12-08 11:43:13","doi":"10.21203/rs.3.rs-7971352/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-02-09T09:55:30+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-12-21T10:19:46+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-12-21T09:46:19+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"97103477960755379825970352312802106111","date":"2025-12-21T09:30:42+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-12-15T17:27:56+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"142119477004253618726800817775599699851","date":"2025-12-13T11:15:40+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"3115074544172540212301189509955098751","date":"2025-12-12T19:30:01+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"165559515919907394166526149008925417223","date":"2025-12-04T15:57:55+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-12-04T13:03:09+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-12-01T20:03:36+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-11-12T10:54:54+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-11-11T14:46:41+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Anesthesiology","date":"2025-11-11T14:43:32+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-anesthesiology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bane","sideBox":"Learn more about [BMC Anesthesiology](http://bmcanesthesiol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bane","title":"BMC Anesthesiology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"68d9595c-2950-4127-863f-40164327bf5b","owner":[],"postedDate":"December 8th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-03-08T18:08:29+00:00","versionOfRecord":[],"versionCreatedAt":"2025-12-08 11:43:13","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7971352","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7971352","identity":"rs-7971352","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}