Biomechanical Analysis of Proximal Femur Bionic Nail in Treating Intertrochanteric Fractures with Different Lateral Wall Classifications: A Finite Element Study

Biomechanical Analysis of Proximal Femur Bionic Nail in Treating Intertrochanteric Fractures with Different Lateral Wall Classifications: A Finite Element 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 Biomechanical Analysis of Proximal Femur Bionic Nail in Treating Intertrochanteric Fractures with Different Lateral Wall Classifications: A Finite Element Study Hao Guo, Cheng Ren, Yibo Xu, Chaofeng Wang, Deyin Liu, Congming Zhang, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6601639/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background This study employed finite element analysis to compare the biomechanical stability of the Proximal Femoral Nail Antirotation (PFNA) and the Proximal Femur Bionic Nail (PFBN) in treating intertrochanteric fractures with different lateral wall classifications. Methods CT scan data from a healthy 45-year-old male were used to construct three-dimensional models of the proximal femur. Using Mimics 21.0, Geomagic Studio, SolidWorks 2017, and ANSYS Workbench, models of PFNA and PFBN were assembled with AO/OTA 31-A1.2 (stable lateral wall), A2.2 (compromised lateral wall), and A3.3 (fractured lateral wall) intertrochanteric fracture types. The bone material properties were set to simulate osteoporosis. ANSYS software was used to simulate standing and walking conditions by applying loads of 700 N (1× body weight) and 1995 N (4× body weight), respectively. The following parameters were analyzed: maximum displacement of the proximal femur, maximum displacement of the internal fixation, maximum stress distribution in the proximal fracture fragment, maximum stress distribution in the internal fixation, and femoral neck varus angle. Results 1.Across all three lateral wall classifications, the PFBN group exhibited significantly lower values for maximum displacement of the proximal femur, maximum displacement of the internal fixation, maximum stress in the internal fixation, and maximum stress in the proximal fracture fragment compared to the PFNA group under both loading conditions. 2.In the A3.3 fracture model, both PFNA and PFBN groups showed higher values for all measured parameters compared to the A1.2 and A2.2 models. 3. In the PFNA group, the maximum stress in the proximal fracture fragment was concentrated at the interface between the fracture surface and the helical blade. In contrast, the PFBN group exhibited stress concentration at the junction of the tension and compression screws, effectively reconstructing the physiological stress distribution of the proximal femur. Conclusion Under both loading conditions, the PFBN demonstrated superior biomechanical stability for intertrochanteric fractures across all lateral wall classifications. This advantage stems from the PFBN's ability to more accurately reconstruct the normal biomechanical pivot point of the hip joint, making it a more effective option for treating intertrochanteric fractures compared to the PFNA. Femoral intertrochanteric fracture Lever-pivot balance PFBN Finite element analysis Lateral wall classification Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Background Hip fractures have garnered increasing attention due to their rising global incidence. In 2019, approximately 14.2 million cases were reported worldwide [1], with intertrochanteric fractures accounting for 42% of these cases [2]. Intramedullary fixation remains the primary treatment, yet postoperative complications such as implant failure, nonunion, loss of reduction, varus collapse, and screw cut-out occur in 6%–20% of cases [3], imposing significant economic and psychological burdens on patients. Restoring hip stability post-surgery is therefore critical. The Proximal Femur Bionic Nail (PFBN), developed by Professor Zhang Yingze and Professor Zhang Dianying based on the "Zhang's N Triangle Theory," [4] mimics the microstructure and biomechanical properties of proximal femoral trabecular bone. Adhering to Wolff's Law and leveraging the lever-pivot principle [5], the PFBN offers superior theoretical and mechanical stability compared to other fixation systems. Intertrochanteric fractures are commonly classified using the Evans or AO systems. Recent studies emphasize the importance of lateral wall integrity, categorizing these fractures into stable, compromised, and fractured lateral wall types [6]. This study utilized finite element analysis to evaluate the biomechanical stability of PFBN and PFNA in treating these fracture types, providing mechanical insights for clinical decision-making. Methods 1.1 Materials CT scan data from a 45-year-old healthy male (height: 170 cm; weight: 70 kg) with no history of hip disease were used. Ethical approval was obtained from the Medical Ethics Committee of Xi'an Honghui Hospital. 1.2 Construction of Femoral Models A 64-slice spiral CT scanner (GE, USA) was used to scan the right proximal femur (parameters: 120 kV, 150 mA, slice thickness: 1.00 mm). The images were processed in Mimics 21.0 to create a preliminary 3D model, which was then refined in Geomagic Studio to produce a smooth, high-quality model (Figure 1). 1.3 Fracture Modeling and Implant Assembly Using SolidWorks 2017, three fracture models (A1.2, A2.2, A3.3) were created based on AO/OTA-2018 classifications [7]. PFNA (main nail length: 170 mm, proximal diameter: 16 mm, distal diameter: 10 mm, helical blade length: 105 mm) and PFBN (main nail length: 170 mm, proximal diameter: 16 mm, distal diameter: 10 mm, compression screw length: 105 mm, tension screw length: 90 mm) models were assembled with the fracture models (Figure 2). 1.3 Material Properties and Boundary Conditions The bone was modeled as homogeneous, isotropic, and linearly elastic. Specifically, the Young's modulus of cancellous bone was set to 285.6 MPa with a Poisson's ratio of 0.3. For cortical bone, the Young's modulus was determined to be 11,256 MPa, also with a Poisson's ratio of 0.3. The internal fixation material (Ti-6Al-4V) exhibited a Young's modulus of 110,000 MPa and a Poisson's ratio of 0.3 [8]. Additionally, the friction coefficient between bones was defined as 0.46 [9], the friction coefficient between bone and screw as 0.3 [10], and the friction coefficient between screws as 0.23 [11]. A binding relationship was established between the femur and the distal locking screw.The distal femur was fixed, and loads of 700 N (standing) and 1995 N (walking) were applied at a 10° angle to the femoral head (Figure 3). 1.4 Mesh Generation Convergence analysis was performed, with mesh size set to 2 mm (Figure 4). We think the experimental results are not affected by mesh quality. Node and element counts are listed in Table 1. 1.5 Outcome Measures The following parameters were analyzed: 1. Maximum stress in the proximal fracture fragment. 2. Maximum displacement of the proximal femur. 3. Maximum displacement of the internal fixation. 4. Maximum stress in the internal fixation. Results 2.1 Maximum Stress in the Proximal Fracture Fragment In the simulated standing position, it was found that the maximum stress of the fracture block in the PFNA group was concentrated on the helical blade, while in the PFBN group, it was concentrated on the compression nail. The maximum stress in the PFBN group was less than that in the PFNA group. As the lateral wall classification changed, the maximum stress of the fracture block in both groups also changed. The maximum stress occurred in the A3.3 classification, which was 5.41 MPa and 4.31 MPa, respectively (Figure 5). To further analyze the stress distribution of the PFBN in the proximal fracture block, we extracted the stress distribution cloud diagrams of the internal fixation in the proximal fracture block of the PFNA and PFBN groups (Figure 6). We found that the maximum stress point in the PFNA group was located at the junction of the helical blade and the main nail, while in the PFBN group, it was located at the junction of the tension nail and the compression nail, which to a certain extent greatly reduced the stress value at the tip of the compression nail. 2.2 Maximum Stress in the Internal Fixation In the A1.2, A2.2, and A3.3 classifications under the standing position, the maximum stress of the proximal femoral nail anti-rotation system (PFNA) is concentrated at the junction between the main nail and the helical blade, with the highest stress value of 310.06 MPa observed in A3.3. For the proximal femoral bone nail (PFBN), the maximum stress is concentrated at the junction between the main nail and the pressure nail, with the highest stress value of 206.04 MPa also occurring in A3.3. During the simulation of the walking gait, the locations of maximum stress for both PFNA and PFBN remained unchanged, while the highest stress values were again recorded in A3.3, reaching 869.42 MPa and 574.71 MPa, respectively (Figure 7). 2.3 Maximum Displacement of the Proximal Femur The maximum displacement of the proximal femur in each model of both the PFNA group and the PFBN group was observed at the region where force was applied to the femoral head (Figure 8). Similarly, during standing and walking gaits, the maximum displacement of the proximal femur in the PFBN group was consistently smaller than that in the PFNA group across different lateral wall classifications. Furthermore, as the severity of lateral wall involvement increased, the maximum displacement of the proximal femur also progressively increased. The peak stress was recorded in type A3.3. During the experiment, it was noted that the variations in maximum stress values of the proximal femur in types A1.2 and A2.2 were relatively minor, whereas the maximum stress in type A3.3 was significantly higher compared to the former two classifications. 2.4 Maximum Displacement of the Internal Fixation In the A1.2, A2.2 and A3.3 classification of the standing position, the maximum displacement of internal fixation in the PFNA group occurred at the top of the helical blade, with the maximum stress value being 24.35mm in A3.3. In the PFBN group, the maximum displacement of internal fixation occurred at the top of the compression nail, with the maximum displacement being 21.75mm in A3.3. When simulating the walking gait, the maximum displacement sites of internal fixation in the PFNA group and the PFBN group did not change, and the maximum stress values also occurred in A3.3, being 66.36mm and 62.61mm respectively (Figure 9). Discussion The lateral wall is the proximal femoral cortical bone from the level of the crest of the vastus lateralis muscle below the apex of the greater trochanter to the midpoint of the lesser trochanter, which is the site for the opening drill hole of the internal fixation implant [13]. GOTFRIED et al. [14][15] believe that the integrity of the lateral wall plays an important role in the stability of the hip after fracture surgery. It has surpassed the traditional posterior-medial bone block in maintaining the stability of intertrochanteric fractures of the femur. The lateral wall is also the attachment point of the gluteus maximus and gluteus minimus muscles. If the lateral wall is ruptured, the soft tissue balance and stability of the hip joint will be greatly affected [16]. Currently, the most common internal fixation treatment for intertrochanteric fractures of the femur is the PFNA treatment plan. However, the reports of internal fixation failure after surgery are increasing year by year, especially when treating intertrochanteric fractures of the femur with ruptured lateral wall, the risk of internal fixation failure is higher. On the one hand, when the spiral blade enters the cancellous bone of the femoral head, it can cause chain fractures of the surrounding bone, resulting in a decrease in the supporting force of the spiral blade and causing loosening and cutting situations. On the other hand, the lateral wall cannot provide effective support for the femoral head-neck fracture block and cannot resist the internal rotation and rotation of the fracture block. With the increasing number of patients and the higher pursuit of treatment effects, new concepts and treatment plans are constantly emerging. This experiment introduces a new internal fixation scheme from the perspective of biomechanics. PFBN is mainly composed of main pins, pressure pins, tension pins and locking pins. The most obvious difference compared with the currently most popular PFNA lies in the addition of tension pins. The design of tension pins and pressure pins is more in line with the main pressure trabeculae and main tension trabeculae of the proximal femur, which are distributed along the main pressure and tension directions. The main pressure trabeculae and main tension trabeculae interweave with each other, which is similar to forming a lever system. Zhang D [17] et al. proposed the "leverage balance reconstruction theory" based on this characteristic. The fulcrum of the leverage system is precisely the junction of the main pressure trabeculae and main tension trabeculae of the proximal femur, which is also the center for maintaining the mechanical balance of the proximal femur. PFBN was designed based on this theory. The tension pins and pressure pins of PFBN cross each other, forming another leverage system. The intersection of tension pins and pressure pins is the fulcrum of the lever system. The vertical distance from the fulcrum to the femoral head is defined as the inner force arm, and the vertical distance from the fulcrum to the external wall of the femur is defined as the outer force arm. When a femoral intertrochanteric fracture occurs, the original mechanical balance is disrupted. The lever structure in PFBN, which is similar to the bionic lever system, has its fulcrum position closer to the normal force-bearing physiological fulcrum of the proximal femur, which can disperse the gravitational load to the tension trabeculae and pressure trabeculae for transmission. At this time, the pressure pins and tension pins can well replace the functions of pressure trabeculae and tension trabeculae [18]. According to the formula, the inner force arm length × gravitational load G = outer force arm length × resistance of the external wall F [20], it can be seen that in the case of unchanged gravitational load G, the inner force arm length increases, the outer force arm length decreases, and the resistance F value of the external wall increases significantly. Therefore, in the "leverage balance reconstruction theory", the risk of postoperative internal fixation failure of PFNA is significantly increased compared with PFBN. The proximal femur has different load-bearing and stability structures from other parts: The proximal femur contains a large amount of rich cancellous bone, mainly ordinary trabeculae and stress trabeculae. Through resisting and buffering bending strain, it plays an important role in maintaining the elastic stability of the femur. It is an important structure for the elastic stability of the proximal femur [21]. Among them, the force-bearing trabeculae and main pressure trabeculae are the most important mechanical structures in the femoral Ward triangle area, spanning the greater trochanter, intertrochanter, femoral neck and femoral head, mainly bearing bending stress and pressure [22]. The triangular structure formed by the tension pins and pressure pins of PFBN corresponds to the Ward triangle composed of the tension trabeculae and pressure trabeculae inside the femur to a certain extent, adding corresponding mechanical theoretical basis to PFBN. With the increasing importance of the external wall, there are few studies on PFBN in treating femoral intertrochanteric fractures of different external wall types compared with existing internal fixation schemes. This article explores the stability of PFBN from the mechanical aspect. The most distinctive feature of this study lies in the experimental method of finite element analysis to simulate the forces under two gait patterns, standing and walking, and to analyze the differences in biomechanical properties of the two internal fixation methods, PFNA and PFBN, in the treatment of intertrochanteric femoral fractures in three lateral wall classification types. In the experiment, it can be seen that in the three intertrochanteric femoral fractures models of lateral wall stable type A1.2, lateral wall dangerous type A2.2, and lateral wall fracture type A3.3, the PFBN group has lower proximal femoral and internal fixation displacements and stress on the proximal femoral fracture fragments and internal fixation compared to the PFNA group. Different lateral wall classifications show better biomechanical properties for PFBN, especially in the treatment of complex unstable intertrochanteric femoral fractures, which is more consistent with the conclusion obtained by Zhang et al. [23]. In the experiment, it was found that at the maximum displacement of the proximal femur and the maximum displacement angle of the internal fixation, the displacements of the proximal femur and internal fixation in A1.2 and A2.2 of both gait patterns were relatively small, but the displacements of the proximal femur and internal fixation in A3.3 were significantly greater than those of the former two classifications. When the displacement of the femur is greater, the stress becomes more concentrated, and the stability of the proximal femoral bone block becomes more unstable. The greater the displacement of the internal fixation, the more obvious the cutting effect of the helical blade or screw, and the higher the risk of cutting out. In the experiment, the displacements of the proximal femur and internal fixation in the PFBN group were significantly lower than those in the PFNA group, so its stability was higher and the risk of screw cutting out was lower. From the stress distribution of the blade or screw, the maximum stress value of PFNA was located at the junction of the main nail and the helical blade, and the maximum stress value of PFBN was located at the junction of the tension nail and the pressure nail. This clearly indicates that the two have different fulcrums and corresponding inner force arms, and in the maximum stress of the proximal femoral bone block, the PFBN group was significantly lower than the PFNA group. From the stress distribution cloud map of internal fixation in the proximal femoral bone block of PFNA and PFBN, the maximum stress of the PFBN group was located at the junction of the tension nail and the pressure nail, which significantly reduced the stress value at the tip of the screw blade and decreased the probability of internal fixation failure, as Wang et al. also indicated through clinical trial research [24]. PFBN has more advantages than PFNA in preventing hip valgus. The finite element analysis method was initially a relatively mature application in the engineering field. It was applied to the orthopedics field starting from the 1970s [25]. Its most prominent feature lies in its simplicity of operation, high degree of simulation, and reusability, which have solved the problems of invasiveness, high cost, and long time consumption in traditional orthopedic mechanics research. The study also has the following shortcomings: In the experiment, the material properties of the femoral bone were set as homogeneous and isotropic; the real properties of bone materials are anisotropic, and there may be certain differences between the experimental results and the real bones in this aspect. Secondly, the reasons for the failure of internal fixation after surgery for intertrochanteric femoral fractures mainly lie in the fracture classification and bone quality. In this experiment, the bone density adopted was based on the data of the osteoporosis model in previous experiments, and no assessment was made for different bone qualities. However, Shen [26] et al. verified that PFBN was more stable than PFNA in fixing A1.3 type intertrochanteric femoral fractures under different bone densities. Conclusion The PFBN represents an innovative approach to treating intertrochanteric fractures. By reconstructing the hip's natural biomechanical pivot and mimicking the trabecular structure, it offers enhanced stability and reduces the risk of complications. This study provides compelling biomechanical evidence supporting the PFBN's clinical application. Abbreviations PFBN Proximal Femur Bionic Nail CT computed tomography PFNA proximal femoral nail anti-rotation Declarations Ethics approval and consent to participate: Ethical clearance was obtained through the Ethics Review Committee of Hong-Hui Hospital, Xi’an Jiaotong University (Z 202170) and the informed consent was obtained from individual or guardian participants. Data collected from participants were kept confidential and were accessible only to the researchers. All methods were performed in accordance with the relevant guidelines and regulations. Consent for publication: Not applicable. Availability of date and materials: All data generated or analysed during this study are included in this published article [and its supplementary information files. Competing interests: The authors declare that they have no competing interests. Funding: This study was supported in part by grants from the basic scientific Research Funds of Provincial universities in 2023 (2023-KYYWF-0516) Authors’ contribution: All authors conceived of the study, took active part in all aspects of the study and read and approved the final manuscript. TM was the lead author of the original report. HG was the main contributor in the process of up-dating and revising the contents of the original report and in preparing this manuscript. Authors’ information: Affiliation: Severe & Poly-trauma Division, Orthopedic Trauma Department, Hong-Hui Hospital, Xi’an Jiaotong University, Xi’an, China Hao Guo, Resident physician of the Severe & Poly-trauma Division, Orthopedic Trauma Department, Hong-Hui Hospital, Xi’an Jiaotong University, Email: [email protected] Cheng Ren, Attending physician of the Severe & Poly-trauma Division, Orthopedic Trauma Department, Hong-Hui Hospital, Xi’an Jiaotong University, Email: [email protected] Yibo Xu, Attending physician of the Severe & Poly-trauma Division, Orthopedic Trauma Department, Hong-Hui Hospital, Xi’an Jiaotong University, Email: [email protected] Chaofeng Wang, Associated chief physician of the Severe & Poly-trauma Division, Orthopedic Trauma Department, Hong-Hui Hospital, Xi’an Jiaotong University, Email: [email protected] Ten Ma, Professor, Chief physician of the Severe & Poly-trauma Division, Orthopedic Trauma Department, Hong-Hui Hospital, Xi’an Jiaotong University, Email: [email protected] Dawei Zhou, Resident physician of the Severe & Poly-trauma Division, Orthopedic Trauma Department, Hong-Hui Hospital, Xi’an Jiaotong University, Email: [email protected] De-yin Liu, Associated chief physician of the Severe & Poly-trauma Division, Orthopedic Trauma Department, Hong-Hui Hospital, Xi’an Jiaotong University, Email: [email protected] Cong-ming Zhang, Associated chief physician of the Severe & Poly-trauma Division, Orthopedic Trauma Department, Hong-Hui Hospital, Xi’an Jiaotong University, Email: [email protected] Dong-yang Li, Resident physician of the Severe & Poly-trauma Division, Orthopedic Trauma Department, Hong-Hui Hospital, Xi’an Jiaotong University, Email: [email protected] Chang-jun He, Resident physician of the Severe & Poly-trauma Division, Orthopedic Trauma Department, Hong-Hui Hospital, Xi’an Jiaotong University, Email: [email protected] Kun Zhang, Chief physician of the Severe & Poly-trauma Division, Orthopedic Trauma Department, Hong-Hui Hospital, Xi’an Jiaotong University, Email: [email protected] . 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Tables Table 1 Numbers of elements and nodes of FEA models Model Nodes elements PFNA-A1.2 2145757 1366574 PFNA-A2.2 2149746 1388317 PFNA-A3.3 2211657 1421511 PFBN-A1.2 2157764 1398919 PFBN-A2.2 2165850 1399569 PFBN-A3.3 2229736 1488353 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted 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. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-6601639","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":462509062,"identity":"5a0b1e3a-7d8b-4386-8e32-afe777da6933","order_by":0,"name":"Hao Guo","email":"","orcid":"","institution":"Hong-Hui Hospital, Xi’an Jiaotong University","correspondingAuthor":false,"prefix":"","firstName":"Hao","middleName":"","lastName":"Guo","suffix":""},{"id":462509063,"identity":"33c89c2d-99c6-4e9d-9600-e29d095eb564","order_by":1,"name":"Cheng Ren","email":"","orcid":"","institution":"Hong-Hui Hospital, Xi’an Jiaotong University","correspondingAuthor":false,"prefix":"","firstName":"Cheng","middleName":"","lastName":"Ren","suffix":""},{"id":462509064,"identity":"7c4b0f5d-deb9-418c-8cc5-bbde69e7d88e","order_by":2,"name":"Yibo Xu","email":"","orcid":"","institution":"Hong-Hui Hospital, Xi’an Jiaotong University","correspondingAuthor":false,"prefix":"","firstName":"Yibo","middleName":"","lastName":"Xu","suffix":""},{"id":462509065,"identity":"5b015812-2a99-4fc7-96da-2d78e2df9a3d","order_by":3,"name":"Chaofeng Wang","email":"","orcid":"","institution":"Hong-Hui Hospital, Xi’an Jiaotong University","correspondingAuthor":false,"prefix":"","firstName":"Chaofeng","middleName":"","lastName":"Wang","suffix":""},{"id":462509066,"identity":"c44d6f20-3524-4f1c-bda1-8b540a4364b9","order_by":4,"name":"Deyin Liu","email":"","orcid":"","institution":"Hong-Hui Hospital, Xi’an Jiaotong University","correspondingAuthor":false,"prefix":"","firstName":"Deyin","middleName":"","lastName":"Liu","suffix":""},{"id":462509067,"identity":"042e3267-6135-46a6-b8c9-aef332ce2467","order_by":5,"name":"Congming Zhang","email":"","orcid":"","institution":"Hong-Hui Hospital, Xi’an Jiaotong University","correspondingAuthor":false,"prefix":"","firstName":"Congming","middleName":"","lastName":"Zhang","suffix":""},{"id":462509068,"identity":"4cc80c36-6a95-4a65-a5e2-a06e830b7d19","order_by":6,"name":"Dawei Zhou","email":"","orcid":"","institution":"Hong-Hui Hospital, Xi’an Jiaotong University","correspondingAuthor":false,"prefix":"","firstName":"Dawei","middleName":"","lastName":"Zhou","suffix":""},{"id":462509069,"identity":"e09d7dad-2693-448c-a60d-a8dfc09da1bb","order_by":7,"name":"Dongyang Li","email":"","orcid":"","institution":"Hong-Hui Hospital, Xi’an Jiaotong University","correspondingAuthor":false,"prefix":"","firstName":"Dongyang","middleName":"","lastName":"Li","suffix":""},{"id":462509070,"identity":"1bd8f018-4ed0-4831-94df-d1819999cbde","order_by":8,"name":"Changjun He","email":"","orcid":"","institution":"Hong-Hui Hospital, Xi’an Jiaotong University","correspondingAuthor":false,"prefix":"","firstName":"Changjun","middleName":"","lastName":"He","suffix":""},{"id":462509071,"identity":"302b9832-3fba-478b-86c4-2d8441c13e55","order_by":9,"name":"Teng Ma","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA0ElEQVRIiWNgGAWjYBACfvb+5x8//pGob2xvIFKLZM8ZNmbJBhvG5p4DRGoxuJHDxsDbkMbYPiOBWC0Hco89kNxxmJl35uONNxhqbKIJO+zAuXSDwjOH2SRnpxVbMBxLy20gpIXvYIOBhATbYR7D2TlmEowNhwlrYTjMYCDBw3ZYwv7mGSK1CBzjMZPgbUszYJzBQ6QWyR62ZGOJMzYJjD1AvyQQ4xd++ccHH36okEhgbD+88caHGhsi/IIEDCQSSFEO0UKqjlEwCkbBKBgZAAAev0NOa2clOgAAAABJRU5ErkJggg==","orcid":"","institution":"Hong-Hui Hospital, Xi’an Jiaotong University","correspondingAuthor":true,"prefix":"","firstName":"Teng","middleName":"","lastName":"Ma","suffix":""},{"id":462509072,"identity":"b119d517-de08-4bf9-b751-018dbabed653","order_by":10,"name":"Kun Zhang","email":"","orcid":"","institution":"Hong-Hui Hospital, Xi’an Jiaotong University","correspondingAuthor":false,"prefix":"","firstName":"Kun","middleName":"","lastName":"Zhang","suffix":""}],"badges":[],"createdAt":"2025-05-06 09:53:27","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6601639/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6601639/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":83623765,"identity":"c6a53492-3791-4493-9b22-3c05c3b09cbd","added_by":"auto","created_at":"2025-05-29 16:00:41","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":45036,"visible":true,"origin":"","legend":"\u003cp\u003eConstruction of the full-length three-dimensional model of the femur\u003c/p\u003e","description":"","filename":"1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6601639/v1/eaa52d7402b0c61bfc057e40.jpg"},{"id":83624446,"identity":"9057ea7e-22a3-4602-836b-a33a6a77bcf3","added_by":"auto","created_at":"2025-05-29 16:08:41","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":25781,"visible":true,"origin":"","legend":"\u003cp\u003eAssembly drawings of PFBN and three types of lateral wall classification models of intertrochanteric fractures of the femur\u003c/p\u003e","description":"","filename":"2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6601639/v1/efc341cfa4aea7920e514160.jpg"},{"id":83624814,"identity":"a289e432-3ee5-417a-871e-f142c40b95a6","added_by":"auto","created_at":"2025-05-29 16:16:41","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":14140,"visible":true,"origin":"","legend":"\u003cp\u003eLoad and constraint schematic diagram\u003c/p\u003e","description":"","filename":"3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6601639/v1/3e8dcdff829ae7abfc91974e.jpg"},{"id":83624444,"identity":"e18b3e2a-a0c3-44db-82ba-860e73d29675","added_by":"auto","created_at":"2025-05-29 16:08:41","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":33933,"visible":true,"origin":"","legend":"\u003cp\u003eGrid convergence verification\u003c/p\u003e","description":"","filename":"4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6601639/v1/a3e51722d630ef19d04654e3.jpg"},{"id":83623772,"identity":"e0525442-7f04-42a4-9f17-5a2cb6542d16","added_by":"auto","created_at":"2025-05-29 16:00:41","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":82120,"visible":true,"origin":"","legend":"\u003cp\u003eThe maximum stress of the proximal femoral fracture fragment in different types under two gaits.\u003c/p\u003e","description":"","filename":"5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6601639/v1/f88dfa60cf6f4af9d91c4b3e.jpg"},{"id":83623770,"identity":"84844f4d-ee09-4428-8efc-e6caf985bdf9","added_by":"auto","created_at":"2025-05-29 16:00:41","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":16582,"visible":true,"origin":"","legend":"\u003cp\u003e(a) is the stress cloud diagram of the PFNA helical blade, and (b) is the pressure pin and tension pin cloud diagram in PFBN.\u003c/p\u003e","description":"","filename":"6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6601639/v1/31bbd73e618601323ab8c757.jpg"},{"id":83623777,"identity":"db6f80a1-6645-4225-b482-cf92ac95c77a","added_by":"auto","created_at":"2025-05-29 16:00:41","extension":"jpg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":56896,"visible":true,"origin":"","legend":"\u003cp\u003eThe maximum stress of internal fixation in different types under two gaits.\u003c/p\u003e","description":"","filename":"7.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6601639/v1/0473f661990ca4e824510394.jpg"},{"id":83623779,"identity":"9638e5a8-9e4d-4e55-8081-b694bcfe1f20","added_by":"auto","created_at":"2025-05-29 16:00:41","extension":"jpg","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":57047,"visible":true,"origin":"","legend":"\u003cp\u003eThe maximum displacement of the proximal femur in different types under the two gaits.\u003c/p\u003e","description":"","filename":"8.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6601639/v1/4cbf1e54dbe13a5266bf9dd4.jpg"},{"id":83623776,"identity":"7f799df6-0fb6-4562-99b7-3326736ee123","added_by":"auto","created_at":"2025-05-29 16:00:41","extension":"jpg","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":53332,"visible":true,"origin":"","legend":"\u003cp\u003eThe maximum displacement of internal fixation in different types under the two gaits\u003c/p\u003e","description":"","filename":"9.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6601639/v1/e31e576f0d28ca2936075c4d.jpg"},{"id":90006881,"identity":"3db47179-a599-468c-9586-fef542d1f2b3","added_by":"auto","created_at":"2025-08-27 09:39:33","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":796672,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6601639/v1/a9355357-de1e-4f94-9683-551222647612.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Biomechanical Analysis of Proximal Femur Bionic Nail in Treating Intertrochanteric Fractures with Different Lateral Wall Classifications: A Finite Element Study","fulltext":[{"header":"Background","content":"\u003cp\u003eHip fractures have garnered increasing attention due to their rising global incidence. In 2019, approximately 14.2 million cases were reported worldwide [1], with intertrochanteric fractures accounting for 42% of these cases [2]. Intramedullary fixation remains the primary treatment, yet postoperative complications such as implant failure, nonunion, loss of reduction, varus collapse, and screw cut-out occur in 6%\u0026ndash;20% of cases [3], imposing significant economic and psychological burdens on patients. Restoring hip stability post-surgery is therefore critical. The Proximal Femur Bionic Nail (PFBN), developed by Professor Zhang Yingze and Professor Zhang Dianying based on the \u0026quot;Zhang\u0026apos;s N Triangle Theory,\u0026quot; [4] mimics the microstructure and biomechanical properties of proximal femoral trabecular bone. Adhering to Wolff\u0026apos;s Law and leveraging the lever-pivot principle [5], the PFBN offers superior theoretical and mechanical stability compared to other fixation systems. \u0026nbsp;Intertrochanteric fractures are commonly classified using the Evans or AO systems. Recent studies emphasize the importance of lateral wall integrity, categorizing these fractures into stable, compromised, and fractured lateral wall types [6]. This study utilized finite element analysis to evaluate the biomechanical stability of PFBN and PFNA in treating these fracture types, providing mechanical insights for clinical decision-making.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e1.1 Materials\u003c/p\u003e\n\u003cp\u003eCT scan data from a 45-year-old healthy male (height: 170 cm; weight: 70 kg) with no history of hip disease were used. Ethical approval was obtained from the Medical Ethics Committee of Xi\u0026apos;an Honghui Hospital.\u003c/p\u003e\n\u003cp\u003e1.2 Construction of Femoral Models\u003c/p\u003e\n\u003cp\u003eA 64-slice spiral CT scanner (GE, USA) was used to scan the right proximal femur (parameters: 120 kV, 150 mA, slice thickness: 1.00 mm). The images were processed in Mimics 21.0 to create a preliminary 3D model, which was then refined in Geomagic Studio to produce a smooth, high-quality model (Figure 1).\u003c/p\u003e\n\u003cp\u003e1.3 Fracture Modeling and Implant Assembly\u003c/p\u003e\n\u003cp\u003eUsing SolidWorks 2017, three fracture models (A1.2, A2.2, A3.3) were created based on AO/OTA-2018 classifications [7]. PFNA (main nail length: 170 mm, proximal diameter: 16 mm, distal diameter: 10 mm, helical blade length: 105 mm) and PFBN (main nail length: 170 mm, proximal diameter: 16 mm, distal diameter: 10 mm, compression screw length: 105 mm, tension screw length: 90 mm) models were assembled with the fracture models (Figure 2).\u003c/p\u003e\n\u003cp\u003e1.3 Material Properties and Boundary Conditions\u003c/p\u003e\n\u003cp\u003eThe bone was modeled as homogeneous, isotropic, and linearly elastic. Specifically, the Young\u0026apos;s modulus of cancellous bone was set to 285.6 MPa with a Poisson\u0026apos;s ratio of 0.3. For cortical bone, the Young\u0026apos;s modulus was determined to be 11,256 MPa, also with a Poisson\u0026apos;s ratio of 0.3. The internal fixation material (Ti-6Al-4V) exhibited a Young\u0026apos;s modulus of 110,000 MPa and a Poisson\u0026apos;s ratio of 0.3 [8]. Additionally, the friction coefficient between bones was defined as 0.46 [9], the friction coefficient between bone and screw as 0.3 [10], and the friction coefficient between screws as 0.23 [11]. A binding relationship was established between the femur and the distal locking screw.The distal femur was fixed, and loads of 700 N (standing) and 1995 N (walking) were applied at a 10\u0026deg; angle to the femoral head (Figure 3).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e1.4 Mesh Generation\u003c/p\u003e\n\u003cp\u003eConvergence analysis was performed, with mesh size set to 2 mm (Figure 4). We think the experimental results are not affected by mesh quality. Node and element counts are listed in Table 1.\u003c/p\u003e\n\u003cp\u003e1.5 Outcome Measures\u003c/p\u003e\n\u003cp\u003eThe following parameters were analyzed: 1. Maximum stress in the proximal fracture fragment. 2. Maximum displacement of the proximal femur. 3. Maximum displacement of the internal fixation. 4. Maximum stress in the internal fixation.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e2.1 Maximum Stress in the Proximal Fracture Fragment\u003c/p\u003e\n\u003cp\u003eIn the simulated standing position, it was found that the maximum stress of the fracture block in the PFNA group was concentrated on the helical blade, while in the PFBN group, it was concentrated on the compression nail. The maximum stress in the PFBN group was less than that in the PFNA group. As the lateral wall classification changed, the maximum stress of the fracture block in both groups also changed. The maximum stress occurred in the A3.3 classification, which was 5.41 MPa and 4.31 MPa, respectively (Figure 5). To further analyze the stress distribution of the PFBN in the proximal fracture block, we extracted the stress distribution cloud diagrams of the internal fixation in the proximal fracture block of the PFNA and PFBN groups (Figure 6). We found that the maximum stress point in the PFNA group was located at the junction of the helical blade and the main nail, while in the PFBN group, it was located at the junction of the tension nail and the compression nail, which to a certain extent greatly reduced the stress value at the tip of the compression nail.\u003c/p\u003e\n\u003cp\u003e2.2 Maximum Stress in the Internal Fixation \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn the A1.2, A2.2, and A3.3 classifications under the standing position, the maximum stress of the proximal femoral nail anti-rotation system (PFNA) is concentrated at the junction between the main nail and the helical blade, with the highest stress value of 310.06 MPa observed in A3.3. For the proximal femoral bone nail (PFBN), the maximum stress is concentrated at the junction between the main nail and the pressure nail, with the highest stress value of 206.04 MPa also occurring in A3.3. During the simulation of the walking gait, the locations of maximum stress for both PFNA and PFBN remained unchanged, while the highest stress values were again recorded in A3.3, reaching 869.42 MPa and 574.71 MPa, respectively (Figure 7).\u003c/p\u003e\n\u003cp\u003e2.3 Maximum Displacement of the Proximal Femur \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe maximum displacement of the proximal femur in each model of both the PFNA group and the PFBN group was observed at the region where force was applied to the femoral head (Figure 8). Similarly, during standing and walking gaits, the maximum displacement of the proximal femur in the PFBN group was consistently smaller than that in the PFNA group across different lateral wall classifications. Furthermore, as the severity of lateral wall involvement increased, the maximum displacement of the proximal femur also progressively increased. The peak stress was recorded in type A3.3. During the experiment, it was noted that the variations in maximum stress values of the proximal femur in types A1.2 and A2.2 were relatively minor, whereas the maximum stress in type A3.3 was significantly higher compared to the former two classifications.\u003c/p\u003e\n\u003cp\u003e2.4 Maximum Displacement of the Internal Fixation\u003c/p\u003e\n\u003cp\u003eIn the A1.2, A2.2 and A3.3 classification of the standing position, the maximum displacement of internal fixation in the PFNA group occurred at the top of the helical blade, with the maximum stress value being 24.35mm in A3.3. In the PFBN group, the maximum displacement of internal fixation occurred at the top of the compression nail, with the maximum displacement being 21.75mm in A3.3. When simulating the walking gait, the maximum displacement sites of internal fixation in the PFNA group and the PFBN group did not change, and the maximum stress values also occurred in A3.3, being 66.36mm and 62.61mm respectively (Figure 9).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe lateral wall is the proximal femoral cortical bone from the level of the crest of the vastus lateralis muscle below the apex of the greater trochanter to the midpoint of the lesser trochanter, which is the site for the opening drill hole of the internal fixation implant [13]. GOTFRIED et al. [14][15] believe that the integrity of the lateral wall plays an important role in the stability of the hip after fracture surgery. It has surpassed the traditional posterior-medial bone block in maintaining the stability of intertrochanteric fractures of the femur. The lateral wall is also the attachment point of the gluteus maximus and gluteus minimus muscles. If the lateral wall is ruptured, the soft tissue balance and stability of the hip joint will be greatly affected [16]. Currently, the most common internal fixation treatment for intertrochanteric fractures of the femur is the PFNA treatment plan. However, the reports of internal fixation failure after surgery are increasing year by year, especially when treating intertrochanteric fractures of the femur with ruptured lateral wall, the risk of internal fixation failure is higher. On the one hand, when the spiral blade enters the cancellous bone of the femoral head, it can cause chain fractures of the surrounding bone, resulting in a decrease in the supporting force of the spiral blade and causing loosening and cutting situations. On the other hand, the lateral wall cannot provide effective support for the femoral head-neck fracture block and cannot resist the internal rotation and rotation of the fracture block. With the increasing number of patients and the higher pursuit of treatment effects, new concepts and treatment plans are constantly emerging. This experiment introduces a new internal fixation scheme from the perspective of biomechanics.\u003c/p\u003e\n\u003cp\u003ePFBN is mainly composed of main pins, pressure pins, tension pins and locking pins. The most obvious difference compared with the currently most popular PFNA lies in the addition of tension pins. The design of tension pins and pressure pins is more in line with the main pressure trabeculae and main tension trabeculae of the proximal femur, which are distributed along the main pressure and tension directions. The main pressure trabeculae and main tension trabeculae interweave with each other, which is similar to forming a lever system. Zhang D [17] et al. proposed the \u0026quot;leverage balance reconstruction theory\u0026quot; based on this characteristic. The fulcrum of the leverage system is precisely the junction of the main pressure trabeculae and main tension trabeculae of the proximal femur, which is also the center for maintaining the mechanical balance of the proximal femur. PFBN was designed based on this theory. The tension pins and pressure pins of PFBN cross each other, forming another leverage system. The intersection of tension pins and pressure pins is the fulcrum of the lever system. The vertical distance from the fulcrum to the femoral head is defined as the inner force arm, and the vertical distance from the fulcrum to the external wall of the femur is defined as the outer force arm. When a femoral intertrochanteric fracture occurs, the original mechanical balance is disrupted. The lever structure in PFBN, which is similar to the bionic lever system, has its fulcrum position closer to the normal force-bearing physiological fulcrum of the proximal femur, which can disperse the gravitational load to the tension trabeculae and pressure trabeculae for transmission. At this time, the pressure pins and tension pins can well replace the functions of pressure trabeculae and tension trabeculae [18]. According to the formula, the inner force arm length\u0026nbsp;\u0026times;\u0026nbsp;gravitational load G = outer force arm length\u0026nbsp;\u0026times;\u0026nbsp;resistance of the external wall F [20], it can be seen that in the case of unchanged gravitational load G, the inner force arm length increases, the outer force arm length decreases, and the resistance F value of the external wall increases significantly. Therefore, in the \u0026quot;leverage balance reconstruction theory\u0026quot;, the risk of postoperative internal fixation failure of PFNA is significantly increased compared with PFBN. The proximal femur has different load-bearing and stability structures from other parts: The proximal femur contains a large amount of rich cancellous bone, mainly ordinary trabeculae and stress trabeculae. Through resisting and buffering bending strain, it plays an important role in maintaining the elastic stability of the femur. It is an important structure for the elastic stability of the proximal femur [21]. Among them, the force-bearing trabeculae and main pressure trabeculae are the most important mechanical structures in the femoral Ward triangle area, spanning the greater trochanter, intertrochanter, femoral neck and femoral head, mainly bearing bending stress and pressure [22]. The triangular structure formed by the tension pins and pressure pins of PFBN corresponds to the Ward triangle composed of the tension trabeculae and pressure trabeculae inside the femur to a certain extent, adding corresponding mechanical theoretical basis to PFBN. With the increasing importance of the external wall, there are few studies on PFBN in treating femoral intertrochanteric fractures of different external wall types compared with existing internal fixation schemes. This article explores the stability of PFBN from the mechanical aspect.\u003c/p\u003e\n\u003cp\u003eThe most distinctive feature of this study lies in the experimental method of finite element analysis to simulate the forces under two gait patterns, standing and walking, and to analyze the differences in biomechanical properties of the two internal fixation methods, PFNA and PFBN, in the treatment of intertrochanteric femoral fractures in three lateral wall classification types. In the experiment, it can be seen that in the three intertrochanteric femoral fractures models of lateral wall stable type A1.2, lateral wall dangerous type A2.2, and lateral wall fracture type A3.3, the PFBN group has lower proximal femoral and internal fixation displacements and stress on the proximal femoral fracture fragments and internal fixation compared to the PFNA group. Different lateral wall classifications show better biomechanical properties for PFBN, especially in the treatment of complex unstable intertrochanteric femoral fractures, which is more consistent with the conclusion obtained by Zhang et al. [23]. In the experiment, it was found that at the maximum displacement of the proximal femur and the maximum displacement angle of the internal fixation, the displacements of the proximal femur and internal fixation in A1.2 and A2.2 of both gait patterns were relatively small, but the displacements of the proximal femur and internal fixation in A3.3 were significantly greater than those of the former two classifications. When the displacement of the femur is greater, the stress becomes more concentrated, and the stability of the proximal femoral bone block becomes more unstable. The greater the displacement of the internal fixation, the more obvious the cutting effect of the helical blade or screw, and the higher the risk of cutting out. In the experiment, the displacements of the proximal femur and internal fixation in the PFBN group were significantly lower than those in the PFNA group, so its stability was higher and the risk of screw cutting out was lower. From the stress distribution of the blade or screw, the maximum stress value of PFNA was located at the junction of the main nail and the helical blade, and the maximum stress value of PFBN was located at the junction of the tension nail and the pressure nail. This clearly indicates that the two have different fulcrums and corresponding inner force arms, and in the maximum stress of the proximal femoral bone block, the PFBN group was significantly lower than the PFNA group. From the stress distribution cloud map of internal fixation in the proximal femoral bone block of PFNA and PFBN, the maximum stress of the PFBN group was located at the junction of the tension nail and the pressure nail, which significantly reduced the stress value at the tip of the screw blade and decreased the probability of internal fixation failure, as Wang et al. also indicated through clinical trial research [24]. PFBN has more advantages than PFNA in preventing hip valgus.\u003c/p\u003e\n\u003cp\u003eThe finite element analysis method was initially a relatively mature application in the engineering field. It was applied to the orthopedics field starting from the 1970s [25]. Its most prominent feature lies in its simplicity of operation, high degree of simulation, and reusability, which have solved the problems of invasiveness, high cost, and long time consumption in traditional orthopedic mechanics research.\u003c/p\u003e\n\u003cp\u003eThe study also has the following shortcomings: In the experiment, the material properties of the femoral bone were set as homogeneous and isotropic; the real properties of bone materials are anisotropic, and there may be certain differences between the experimental results and the real bones in this aspect. Secondly, the reasons for the failure of internal fixation after surgery for intertrochanteric femoral fractures mainly lie in the fracture classification and bone quality. In this experiment, the bone density adopted was based on the data of the osteoporosis model in previous experiments, and no assessment was made for different bone qualities. However, Shen [26] et al. verified that PFBN was more stable than PFNA in fixing A1.3 type intertrochanteric femoral fractures under different bone densities.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThe PFBN represents an innovative approach to treating intertrochanteric fractures. By reconstructing the hip\u0026apos;s natural biomechanical pivot and mimicking the trabecular structure, it offers enhanced stability and reduces the risk of complications. This study provides compelling biomechanical evidence supporting the PFBN\u0026apos;s clinical application.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003ePFBN\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eProximal Femur Bionic Nail\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eCT\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003ecomputed tomography\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003ePFNA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eproximal femoral nail anti-rotation\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003eEthics approval and consent to participate: Ethical clearance was obtained through the Ethics Review Committee of Hong-Hui Hospital, Xi\u0026rsquo;an Jiaotong\u0026nbsp;University (Z 202170) and the informed consent was obtained from individual or guardian participants. Data\u0026nbsp;collected from participants were kept confidential and were accessible only to the researchers. All methods were performed in accordance with the relevant guidelines and regulations.\u003c/p\u003e\n\u003cp\u003eConsent for publication: Not applicable.\u003c/p\u003e\n\u003cp\u003eAvailability of date and materials: All data generated or analysed during this study are included in this published article [and its supplementary information files.\u003c/p\u003e\n\u003cp\u003eCompeting interests:\u0026nbsp;The authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003eFunding: This study was supported in part by grants from the basic scientific Research Funds of \u0026nbsp;Provincial universities in 2023 (2023-KYYWF-0516)\u003c/p\u003e\n\u003cp\u003eAuthors\u0026rsquo; contribution:\u0026nbsp;All authors conceived of the study, took active part in all aspects of the study and read and approved the final manuscript. TM was the lead author of the original report. HG was the main contributor in the process of up-dating and revising the contents of the original report and in preparing this manuscript.\u003c/p\u003e\n\u003cp\u003eAuthors\u0026rsquo; information:\u003c/p\u003e\n\u003cp\u003eAffiliation:\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eSevere \u0026amp; Poly-trauma Division, Orthopedic Trauma Department, Hong-Hui Hospital, Xi\u0026rsquo;an Jiaotong University, Xi\u0026rsquo;an, China\u003c/p\u003e\n\u003cp\u003eHao Guo, Resident physician of the\u0026nbsp;Severe \u0026amp; Poly-trauma Division, Orthopedic Trauma Department, Hong-Hui Hospital, Xi\u0026rsquo;an Jiaotong University, Email: [email protected]\u003c/p\u003e\n\u003cp\u003eCheng Ren, Attending physician of the Severe \u0026amp; Poly-trauma Division, Orthopedic Trauma Department, Hong-Hui Hospital, Xi\u0026rsquo;an Jiaotong University, Email: [email protected]\u003c/p\u003e\n\u003cp\u003eYibo Xu, Attending physician of the Severe \u0026amp; Poly-trauma Division, Orthopedic Trauma Department, Hong-Hui Hospital, Xi\u0026rsquo;an Jiaotong University, Email: [email protected]\u003c/p\u003e\n\u003cp\u003eChaofeng Wang, Associated chief physician of the Severe \u0026amp; Poly-trauma Division, Orthopedic Trauma Department, Hong-Hui Hospital, Xi\u0026rsquo;an Jiaotong University, Email: [email protected]\u003c/p\u003e\n\u003cp\u003eTen Ma, Professor, Chief physician of the Severe \u0026amp; Poly-trauma Division, Orthopedic Trauma Department, Hong-Hui Hospital, Xi\u0026rsquo;an Jiaotong University, Email: [email protected]\u003c/p\u003e\n\u003cp\u003eDawei Zhou, Resident physician of the Severe \u0026amp; Poly-trauma Division, Orthopedic Trauma Department, Hong-Hui Hospital, Xi\u0026rsquo;an Jiaotong University, Email: [email protected]\u003c/p\u003e\n\u003cp\u003eDe-yin Liu, Associated chief physician of the Severe \u0026amp; Poly-trauma Division, Orthopedic Trauma Department, Hong-Hui Hospital, Xi\u0026rsquo;an Jiaotong University, Email:[email protected]\u003c/p\u003e\n\u003cp\u003eCong-ming Zhang, Associated chief physician of the Severe \u0026amp; Poly-trauma Division, Orthopedic Trauma Department, Hong-Hui Hospital, Xi\u0026rsquo;an Jiaotong University, Email:[email protected]\u003c/p\u003e\n\u003cp\u003eDong-yang Li, Resident physician of the\u0026nbsp;Severe \u0026amp; Poly-trauma Division, Orthopedic Trauma Department, Hong-Hui Hospital, Xi\u0026rsquo;an Jiaotong University, Email:[email protected]\u003c/p\u003e\n\u003cp\u003eChang-jun He, Resident physician of the\u0026nbsp;Severe \u0026amp; Poly-trauma Division, Orthopedic Trauma Department, Hong-Hui Hospital, Xi\u0026rsquo;an Jiaotong University, Email:[email protected]\u003c/p\u003e\n\u003cp\u003eKun Zhang, Chief physician of the Severe \u0026amp; Poly-trauma Division, Orthopedic Trauma Department, Hong-Hui Hospital, Xi\u0026rsquo;an Jiaotong University, Email:[email protected].\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eGBD 2019 Fracture Collaborators. Global, regional, and national burden of bone fractures in 204 countries and territories, 1990-2019: a systematic analysis from the Global Burden of Disease Study 2019. Lancet Healthy Longev. 2021;2(9):e580-e592. doi:10.1016/S2666-7568(21)00172-0.\u003c/li\u003e\n\u003cli\u003eAdeyemi A, Delhougne G. Incidence and Economic Burden of Intertrochanteric Fracture: A Medicare Claims Database Analysis. JB JS Open Access. 2019;4(1):e0045. Published 2019 Feb 27. doi:10.2106/JBJS.OA.18.00045.\u003c/li\u003e\n\u003cli\u003eChehade MJ, Carbone T, Awwad D, et al. Influence of Fracture Stability on Early Patient Mortality and Reoperation After Pertrochanteric and Intertrochanteric Hip Fractures [published correction appears in J Orthop Trauma. 2017 May;31(5):e166. doi: 10.1097/BOT.0000000000000852.\u003c/li\u003e\n\u003cli\u003eZhang D: Buttress and stretch effect of internal fixation for femoral intertrochanteric fractures. Chin J Orthop 2022, 42(02):77-83. doi: 10.3760/cma.j.cn121113-20211123-00674.\u003c/li\u003e\n\u003cli\u003eJulius Wolff (1836-1902). Morphogenesis of bone. JAMA. 1970;213(13):2260.\u003c/li\u003e\n\u003cli\u003eSun LL, Li Q, Chang SM. The thickness of proximal lateral femoral wall. Injury. 2016;47(3):784-785. doi:10.1016/j.injury.2016.01.002.\u003c/li\u003e\n\u003cli\u003eMeinberg EG, Agel J, Roberts CS, Karam MD, Kellam JF. Fracture and Dislocation Classification Compendium-2018. J Orthop Trauma. 2018 Jan;32 Suppl 1:S1-S170. doi: 10.1097/BOT.0000000000001063.\u003c/li\u003e\n\u003cli\u003eCui H, Wei W, Shao Y, Du K. Finite element analysis of fixation effect for femoral neck fracture under different fixation configurations. Comput Methods Biomech Biomed Engin. 2022;25(2):132-139. doi:10.1080/10255842.2021.1935899.\u003c/li\u003e\n\u003cli\u003eLi J, Zhao Z, Yin P, Zhang L, Tang P. Comparison of three different internal fixation implants in treatment of femoral neck fracture-a finite element analysis [published correction appears in J Orthop Surg Res. 2019 Apr 16;14(1):106. doi: 10.1186/s13018-019-1148-3.]. J Orthop Surg Res. 2019;14(1):76. Published 2019 Mar 12. doi:10.1186/s13018-019-1097-x.\u003c/li\u003e\n\u003cli\u003eChen WP, Tai CL, Shih CH, Hsieh PH, Leou MC, Lee MS. Selection of fixation devices in proximal femur rotational osteotomy: clinical complications and finite element analysis. Clin Biomech (Bristol). 2004;19(3):255-262. doi:10.1016/j.clinbiomech.2003.12.003.\u003c/li\u003e\n\u003cli\u003eEberle S, Gerber C, von Oldenburg G, Hungerer S, Augat P. Type of hip fracture determines load share in intramedullary osteosynthesis. Clin Orthop Relat Res. 2009;467(8):1972-1980. doi:10.1007/s11999-009-0800-3.\u003c/li\u003e\n\u003cli\u003eBergmann G, Deuretzbacher G, Heller M. Hip contact forces and gait patterns from routine activities. J Biomech. 2001;34(7):859-871. doi:10.1016/s0021-9290(01)00040-9.\u003c/li\u003e\n\u003cli\u003eChang SM, Hou ZY, Hu SJ, Du SC. Intertrochanteric Femur Fracture Treatment in Asia: What We Know and What the World Can Learn. Orthop Clin North Am. 2020;51(2):189-205. doi:10.1016/j.ocl.2019.11.011.\u003c/li\u003e\n\u003cli\u003eGotfried Y. The lateral trochanteric wall: a key element in the reconstruction of unstable pertrochanteric hip fractures. Clin Orthop Relat Res. 2004;(425):82-86.\u003c/li\u003e\n\u003cli\u003ePalm H, Jacobsen S, Sonne-Holm S, Gebuhr P; Hip Fracture Study Group. Integrity of the lateral femoral wall in intertrochanteric hip fractures: an important predictor of a reoperation. J Bone Joint Surg Am. 2007;89(3):470-475. doi:10.2106/JBJS.F.00679.\u003c/li\u003e\n\u003cli\u003eHao Y, Zhang Z, Zhou F, et al. Risk factors for implant failure in reverse oblique and transverse intertrochanteric fractures treated with proximal femoral nail antirotation (PFNA). J Orthop Surg Res. 2019;14(1):350. Published 2019 Nov 8. doi:10.1186/s13018-019-1414-4.\u003c/li\u003e\n\u003cli\u003eZhang D: Re-recognition of the role of lateral wall of proximal femur based on the theory of lever-pivot balance. Chin J Trauma 2022, 38(06):481-486. doi: 10.3760/cma.j.cn501098-20220222-00130.\u003c/li\u003e\n\u003cli\u003eZhu Y, Chen W, Ye D, Zhang Q, Lyu H, Zheng Z, Zhang Y: Proximal Femur N Triangle Theory and the Design Concept of Proximal Femur Bionic Nail (PFBN). Chin J Geriatr Orthop Rehabil (Electronic Edition) 2021, 7(05):257-259. doi: 10.3877/cma.j.issn.2096-0263.2021.05.001.\u003c/li\u003e\n\u003cli\u003eZhang D: Re-recognition of the role of lateral wall of proximal femur based on the theory of lever-pivot balance. Chin J Trauma 2022, 38(06):481-486. doi: 10.3760/cma.j.cn115530-20240507-00197.\u003c/li\u003e\n\u003cli\u003eZhang Dianying, Yu Kai, Yang Jian, Zhao Xiaotao, Zhang Xiaomeng, Wang Yanhua, Ju Jiabao. Lever-pivot balance:a neodoxy on treatment for intertrochanteric femoral fractures[J]. Chin J Trauma, 2020,36(7):647-651. doi: 10.3760/cma.j.issn.1001-8050.2020.07.013.\u003c/li\u003e\n\u003cli\u003eThomas CD, Mayhew PM, Power J, et al. Femoral neck trabecular bone: loss with aging and role in preventing fracture. J Bone Miner Res. 2009;24(11):1808-1818. doi:10.1359/jbmr.090504.\u003c/li\u003e\n\u003cli\u003eChristopher JJ, Ramakrishnan S. Assessment and classification of mechanical strength components of human femur trabecular bone using texture analysis and neural network. J Med Syst. 2008;32(2):117-122. doi:10.1007/s10916-007-9114-8.\u003c/li\u003e\n\u003cli\u003eWang Y, Yu W, Wu G, Zhang W, Pan J, Zhu W, He Z, Xu P, Jia C: Comparison of two kinds of proximal femoral intramedullary nail for intertrochanteric femoral fractures in the elderly. Orthopedic Journal of China 2023, 31(04):300-304.\u003c/li\u003e\n\u003cli\u003eWang Y, Yu W, Wu G, Zhang W, Pan J, Zhu W, He Z, Xu P, Jia C: Comparison of two kinds of proximal femoral intramedullary nail for intertrochanteric femoral fractures in the elderly. Orthopedic Journal of China 2023, 31(04):300-304. doi: 10.3977/j.issn.1005-8478.2023.04.03.\u003c/li\u003e\n\u003cli\u003eBrekelmans WA, Poort HW, Slooff TJ. A new method to analyse the mechanical behaviour of skeletal parts. Acta Orthop Scand. 1972;43(5):301-317. doi:10.3109/17453677208998949. \u003c/li\u003e\n\u003cli\u003eShen X, Guo H, Chen G, et al. Finite element analysis of proximal femur bionic nail for treating intertrochanteric fractures in osteoporotic bone. Comput Methods Biomech Biomed Engin. Published online May 20, 2024. doi:10.1080/10255842.2024.2355492.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" align=\"\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"3\" valign=\"top\" style=\"width: 100%;\"\u003e\n \u003cp\u003eTable 1 Numbers of elements and nodes of FEA models\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 61.9658%;\"\u003e\n \u003cp\u003eModel\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.3077%;\"\u003e\n \u003cp\u003eNodes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.7265%;\"\u003e\n \u003cp\u003eelements\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 61.9658%;\"\u003e\n \u003cp\u003ePFNA-A1.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.3077%;\"\u003e\n \u003cp\u003e2145757\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.7265%;\"\u003e\n \u003cp\u003e1366574\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 61.9658%;\"\u003e\n \u003cp\u003ePFNA-A2.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.3077%;\"\u003e\n \u003cp\u003e2149746\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.7265%;\"\u003e\n \u003cp\u003e1388317\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 61.9658%;\"\u003e\n \u003cp\u003ePFNA-A3.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.3077%;\"\u003e\n \u003cp\u003e2211657\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.7265%;\"\u003e\n \u003cp\u003e1421511\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 61.9658%;\"\u003e\n \u003cp\u003ePFBN-A1.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.3077%;\"\u003e\n \u003cp\u003e2157764\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.7265%;\"\u003e\n \u003cp\u003e1398919\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 61.9658%;\"\u003e\n \u003cp\u003ePFBN-A2.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.3077%;\"\u003e\n \u003cp\u003e2165850\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.7265%;\"\u003e\n \u003cp\u003e1399569\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 61.9658%;\"\u003e\n \u003cp\u003ePFBN-A3.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.3077%;\"\u003e\n \u003cp\u003e2229736\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 20.7265%;\"\u003e\n \u003cp\u003e1488353\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"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":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Femoral intertrochanteric fracture, Lever-pivot balance, PFBN, Finite element analysis, Lateral wall classification","lastPublishedDoi":"10.21203/rs.3.rs-6601639/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6601639/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eThis study employed finite element analysis to compare the biomechanical stability of the Proximal Femoral Nail Antirotation (PFNA) and the Proximal Femur Bionic Nail (PFBN) in treating intertrochanteric fractures with different lateral wall classifications.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eCT scan data from a healthy 45-year-old male were used to construct three-dimensional models of the proximal femur. Using Mimics 21.0, Geomagic Studio, SolidWorks 2017, and ANSYS Workbench, models of PFNA and PFBN were assembled with AO/OTA 31-A1.2 (stable lateral wall), A2.2 (compromised lateral wall), and A3.3 (fractured lateral wall) intertrochanteric fracture types. The bone material properties were set to simulate osteoporosis. ANSYS software was used to simulate standing and walking conditions by applying loads of 700 N (1\u0026times; body weight) and 1995 N (4\u0026times; body weight), respectively. The following parameters were analyzed: maximum displacement of the proximal femur, maximum displacement of the internal fixation, maximum stress distribution in the proximal fracture fragment, maximum stress distribution in the internal fixation, and femoral neck varus angle.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003e1.Across all three lateral wall classifications, the PFBN group exhibited significantly lower values for maximum displacement of the proximal femur, maximum displacement of the internal fixation, maximum stress in the internal fixation, and maximum stress in the proximal fracture fragment compared to the PFNA group under both loading conditions. 2.In the A3.3 fracture model, both PFNA and PFBN groups showed higher values for all measured parameters compared to the A1.2 and A2.2 models. 3. In the PFNA group, the maximum stress in the proximal fracture fragment was concentrated at the interface between the fracture surface and the helical blade. In contrast, the PFBN group exhibited stress concentration at the junction of the tension and compression screws, effectively reconstructing the physiological stress distribution of the proximal femur.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eUnder both loading conditions, the PFBN demonstrated superior biomechanical stability for intertrochanteric fractures across all lateral wall classifications. This advantage stems from the PFBN's ability to more accurately reconstruct the normal biomechanical pivot point of the hip joint, making it a more effective option for treating intertrochanteric fractures compared to the PFNA.\u003c/p\u003e","manuscriptTitle":"Biomechanical Analysis of Proximal Femur Bionic Nail in Treating Intertrochanteric Fractures with Different Lateral Wall Classifications: A Finite Element Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-05-29 16:00:36","doi":"10.21203/rs.3.rs-6601639/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"43c82c2d-6a87-4565-8358-1c281ea56861","owner":[],"postedDate":"May 29th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-11-23T12:23:06+00:00","versionOfRecord":[],"versionCreatedAt":"2025-05-29 16:00:36","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6601639","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6601639","identity":"rs-6601639","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}