Biomechanical Study of Medial Buttress Plate Combined with Cannulated Compression Screws for Pauwels Type III Femoral Neck Fractures Using Cadaveric Specimens

Biomechanical Study of Medial Buttress Plate Combined with Cannulated Compression Screws for Pauwels Type III Femoral Neck Fractures Using Cadaveric Specimens | 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 Study of Medial Buttress Plate Combined with Cannulated Compression Screws for Pauwels Type III Femoral Neck Fractures Using Cadaveric Specimens Yeqiang Luo, Tianmo Bai, Jingyi Wu, Shanghui Lin, Baofeng Li This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7734693/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 15 You are reading this latest preprint version Abstract Purpose To investigate the biomechanical advantages of medial buttress plate (MBP) combined with inverted triangle cannulated compression screws (CCS) in the internal fixation of Pauwels type III femoral neck fractures, and to provide experimental evidence for optimizing treatment strategies for vertically unstable femoral neck fractures. Methods Twelve adult embalmed femoral specimens were used to create Pauwels type III femoral neck fracture models and randomly assigned to two groups: CCS group and CCS + MBP group (n = 6 each). After standardized internal fixation procedures, axial compression, torsional stiffness, and failure load were tested using a Bose ElectroForce 3510 biomechanical testing system, and all measurements were recorded. Differences between groups were analyzed with independent-samples t-tests, with statistical significance set at P < 0.05. Results Compared with the CCS group, the CCS + MBP group demonstrated significantly higher axial stiffness (562.95 ± 88.26 N/mm vs. 171.02 ± 44.98 N/mm), torsional stiffness (3.24 ± 0.43 N·m/° vs. 2.28 ± 0.51 N·m/°), and failure load (2523.08 ± 432.71 N vs. 1567.88 ± 209.96 N) ( P < 0.05 for all). Conclusion The combination of MBP and CCS provides significantly greater mechanical stability than CCS alone in Pauwels type III femoral neck fractures. This construct disperses shear forces, improves the biomechanical environment for fracture healing, and may reduce postoperative complications and implant failure risk. These findings provide experimental evidence for optimizing internal fixation design and surgical strategies for vertically unstable femoral neck fractures. Level of evidence: I Femoral neck fracture Pauwels type III Cannulated compression screw Medial buttress plate Biomechanics Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 1. Introduction Femoral neck fracture (FNF) is a common type of hip fracture, accounting for approximately 3.6% of all fractures and 57% of hip fractures[ 1 ].In recent years, with the aging population and the increasing incidence of traffic accidents, the prevalence of FNF has been rising, and the proportion of younger patients is gradually increasing. In this population, FNFs are often caused by high-energy trauma and typically present as vertical, unstable Pauwels type III fractures[ 2 ]. Currently, internal fixation techniques for vertically unstable FNFs include cannulated compression screws (CCS), dynamic hip screws (DHS), femoral neck system (FNS), and proximal femoral locking plates (PFLP) [ 3 – 5 ]. Among these, the inverted triangle CCS configuration is widely used for treating FNFs in young and middle-aged adults due to its minimally invasive approach, technical simplicity, and reliable fixation[ 3 , 6 ].However, Pauwels type III fractures (Pauwels angle > 50°) feature a near-vertical fracture line subjected to substantial shear forces. CCS alone often fails to provide sufficient angular stability and resistance to shear stress, leading to complications such as implant loosening and secondary fracture displacement[ 7 ]. To address these challenges, the combination of a medial buttress plate (MBP) placed anteroinferior to the fracture line with an inverted triangle CCS configuration has been proposed to improve resistance to vertical shear forces. Studies have shown that this construct not only reduces the incidence of varus collapse but also converts detrimental shear forces into compressive stress that facilitates fracture healing, thereby optimizing the biomechanical environment[ 8 , 9 ]. Previous finite element analyses and clinical follow-up studies have demonstrated favorable biomechanical performance and clinical outcomes of the CCS + MBP construct in Pauwels type III FNFs[ 9 , 10 ]. However, direct biomechanical validation of this fixation strategy using cadaveric models remains limited. Building upon prior findings, this study employed fresh adult femoral specimens to establish Pauwels type III FNF models and compared the fixation performance of CCS + MBP with CCS alone in vertically unstable fractures. The goal was to provide experimental evidence to guide the optimization of treatment strategies for Pauwels type III FNFs. 2. Materials and Methods 2.1 Specimen preparation A total of 12 adult femoral specimens was obtained from the Department of Anatomy, Southern Medical University. All specimens were sourced from voluntarily donated, embalmed cadavers. Pre-experimental radiographic examinations confirmed the absence of fractures, tumors, or other pathological changes. Bone mineral density (BMD) was measured using dual-energy X-ray absorptiometry (DXA), and no statistically significant differences in BMD were found among specimens. The study protocol was approved by the Ethics Committee of the General Hospital of the Southern Theater Command of the People’s Liberation Army and the Ethics Committee of Southern Medical University. Specimens were thawed at room temperature for 24 hours prior to testing, and all muscles, ligaments, and soft tissues were carefully removed, preserving only the complete bony structures and joint capsules. 2.2 Experimental grouping and fracture modeling Specimens were randomly assigned into two groups (n = 6 each) using a computer-generated random number table: Cannulated compression screw group (CCS) Cannulated compression screw combined with medial buttress plate group (CCS + MBP). Pauwels type III femoral neck fracture models were created following the method described by Markus et al.[ 11 ]. A horizontal osteotomy was performed at the distal femur to standardize specimen length. The osteotomy angle was measured and marked using a goniometer, and a precision oscillating saw was used to create the fracture. The osteotomy started at the proximal femoral neck near the femoral head and extended downward at a 70° Pauwels angle to the femoral neck base, forming a 20° angle with the femoral shaft axis to simulate a typical Pauwels type III vertically unstable fracture ( Fig. 1 ). 2.3 Internal fixation technique Pilot drilling: Prior to osteotomy, under fluoroscopic guidance, pilot drilling for screw channels was performed to ensure anatomical reduction and consistent screw trajectory. Kirschner wires were inserted 3–5 cm below the greater trochanter along the femoral neck axis, following the principles of divergence, subcortical placement, and parallelism. Wire tips were positioned in the subchondral bone approximately 5 mm beneath the articular surface (Fig. 2A ). CCS group: Three 7.3-mm cannulated compression screws were inserted in an inverted triangle configuration. The inferior screw was placed through the calcar to provide vertical support, while the other two screws were positioned anteriorly and posteriorly along the femoral neck cortex, with their tips approximately 5 mm from the subchondral bone ( Fig. 2B ). CCS+MBP group: The screw placement was identical to the CCS group, with the addition of a one-third tubular medial buttress plate on the medial femoral neck, secured with three cortical screws. The plate was positioned slightly proximal to the fracture line to enhance medial support and overall construct stability ( Fig. 2C ). To avoid malreduction caused by plate placement prior to osteotomy, the plate was applied after fracture creation. All fixation procedures were performed by the same senior orthopedic surgeon and verified with fluoroscopy for anatomical reduction. 2.4 Specimen mounting To ensure specimen stability during biomechanical testing and simulate the load-bearing condition of single-leg stance, the distal femur was embedded in a custom base to maintain consistent positioning. The distal femur was trimmed to 40 cm in length. A self-curing dental acrylic resin mixture was poured into a custom mold, and the distal femur was inserted in a neutral sagittal position, with 15° adduction in the coronal plane and sagittal alignment to mimic single-leg stance. A custom jig was used to secure the femur, and specimens were left to cure at room temperature for approximately 30 minutes to achieve rigid fixation. This method effectively prevented specimen movement or displacement during testing, ensuring accuracy and reproducibility ( Fig. 3 ). 2.5 Biomechanical testing Biomechanical tests were conducted using a Bose ElectroForce 3510 testing system: Axial compression test: Each specimen was preloaded to 100 N five times to eliminate initial gaps and material creep. Vertical loading was then applied at a rate of 20 N/s until reaching 700 N to simulate the maximal physiological load during single-leg stance. Displacement was recorded in real time, and load–displacement curves were plotted. Axial stiffness was calculated from the slope of the linear portion of the curve ( Fig. 4A ). Torsional stiffness test: Each specimen was preconditioned with five cycles of 3° torsion, followed by torsional loading at a rate of 0.5°/s up to 5°. Torque–angle curves were generated, and torsional stiffness was determined from the slope. Throughout testing, specimens were kept moist with saline spray to maintain their biomechanical properties ( Fig. 4B ). Failure test: Specimens were returned to their initial position and vertically loaded until construct failure. Failure was defined as: A sudden drop in the load–displacement curve; New fracture lines or displacement of fracture fragments; Fracture-end displacement >10 mm; Screw loosening or plate deformation; Implant fracture or detachment from bone. Failure load was recorded as the ultimate load-bearing capacity of the construct ( Fig. 4C ). 2.6 Statistical analysis All data were analyzed using SPSS software. Continuous variables are presented as mean ± standard deviation (SD) and compared using independent-samples t-tests. Categorical variables are presented as percentages and analyzed with the χ² test or corrected χ² test. A P value of <0.05 was considered statistically significant. 3. Results This study compared femoral neck bone mineral density (BMD), axial stiffness, torsional stiffness, and failure load between the CCS group and CCS + MBP group. No significant difference in BMD was found between groups ( P > 0.05), ensuring comparability of baseline conditions. The CCS + MBP construct demonstrated significantly higher axial stiffness, torsional stiffness, and failure load compared with CCS alone ( P < 0.05), indicating superior overall stability in Pauwels type III femoral neck fractures. Detailed results are presented below. 3.1 Bone mineral density BMD of the femoral neck was measured using dual-energy X-ray absorptiometry (DXA). The mean BMD was 0.723 ± 0.199 g/cm² in the CCS group and 0.782 ± 0.164 g/cm² in the CCS + MBP group, with no statistically significant difference between groups ( P > 0.05) ( Table 1 ). 3.2 Axial stiffness Load–displacement curves from axial compression tests exhibited linear characteristics in both groups ( Fig. 5 ). The mean axial stiffness was 171.02 ± 44.98 N/mm in the CCS group and 562.95 ± 88.26 N/mm in the CCS + MBP group ( Table 2 ). Statistical analysis showed a significantly higher axial stiffness in the CCS + MBP group compared with the CCS group ( P < 0.05). 3.3 Torsional stiffness Torque–angle curves obtained from torsional tests were linear in both groups ( Fig. 6 ). The mean torsional stiffness was 2.28 ± 0.51 N·m/° in the CCS group and 3.24 ± 0.43 N·m/° in the CCS + MBP group ( Table 3 ). The CCS + MBP group demonstrated significantly greater torsional stiffness than the CCS group ( P < 0.05). Within the torsion range of 1°–5°, torque values in the CCS + MBP group were consistently higher than those in the CCS group ( P < 0.05). 3.4 Failure load Failure testing showed that the mean failure load was 1567.88 ± 209.96 N in the CCS group and 2523.08 ± 432.71 N in the CCS + MBP group ( Table 4 ). The difference between groups was statistically significant ( P < 0.05), indicating that the CCS + MBP construct provides superior stability under high load conditions compared with CCS alone. 4. Discussion Femoral neck fractures are a common yet severe injury in trauma orthopedics, with an increasing incidence due to population aging, and they remain a major cause of disability and mortality. In young and middle-aged patients, femoral neck fractures are typically caused by high-energy trauma, such as traffic accidents or falls from height. Pauwels type III fractures, characterized by a nearly vertical fracture line, are particularly challenging to manage due to significantly increased shear stress at the femoral neck and the high technical demands of internal fixation[ 2 , 12 – 14 ]. Studies have reported complication rates as high as 45% for high-energy femoral neck fractures, with common complications including nonunion, avascular necrosis of the femoral head, and impaired hip function[ 15 – 17 ]. Thus, achieving accurate anatomic reduction, ensuring rigid and reliable fixation, and reducing complication rates remain key challenges in treating these injuries in physiologically young patients. For displaced femoral neck fractures in elderly patients, arthroplasty is the preferred treatment, whereas anatomic reduction followed by stable internal fixation remains the gold standard in younger individuals[ 18 – 20 ]. Current fixation methods include the inverted triangular configuration of three cannulated compression screws (CCS), dynamic hip screw (DHS), and femoral neck system (FNS). CCS fixation is widely used due to its minimally invasive nature, ease of operation, and satisfactory stability. However, its shear and rotational resistance are limited in Pauwels type III fractures, often leading to screw loosening and redisplacement of the fracture[ 3 , 7 , 21 , 22 ]. DHS is anatomically compatible with the proximal femur and provides excellent axial compression and stability[ 23 ]. Nonetheless, its rotational stability is inadequate, and the insertion of a large lag screw may compromise residual vascular supply, increasing the risk of avascular necrosis[ 4 , 24 ]. FNS, a novel minimally invasive system, offers multidirectional stability while minimizing bone loss, and studies have shown that it reduces postoperative complications and improves union rates in Pauwels type III fractures, though large-scale studies are needed to validate long-term outcomes[ 5 , 25 , 26 ]. Recently, scholars have proposed augmenting the inverted triangular CCS configuration with a medial buttress plate (MBP) to enhance shear resistance and optimize stress distribution[ 8 , 27 – 29 ]. The MBP converts vertical shear forces into compressive forces across the fracture site, thereby creating a more favorable biomechanical environment for healing and offering a promising strategy for stabilizing Pauwels type III fractures. Based on a thorough review of the strengths and weaknesses of current fixation techniques, this study established Pauwels type III fracture models in cadaveric femora to compare the biomechanical performance of CCS alone and CCS combined with MBP. Experimental evaluation of key parameters—including axial stiffness, torsional stiffness, and failure load—demonstrated that the addition of MBP significantly improves the overall stability of fixation constructs. In axial compression testing, the CCS + MBP group exhibited significantly greater mean axial stiffness than the CCS group (562.95 ± 88.26 N/mm vs. 171.02 ± 44.98 N/mm, P < 0.05), suggesting that medial plating markedly enhances vertical stability. This effect can be attributed to the plate’s “buttress” function along the medial cortex, which transfers part of the axial load from the screw–trabecular bone interface to the plate–cortical bone contact interface, effectively transforming shear forces into compressive stresses conducive to healing. This tripod-like load-sharing structure reduces micromotion at the fracture site and supports early weight-bearing and rehabilitation. In contrast, CCS fixation relies solely on interscrew friction and cancellous bone support, which are insufficient for vertically oriented fractures, resulting in a higher risk of construct instability. The torsional tests revealed that torsional stiffness was significantly higher in the CCS + MBP group than in the CCS group (3.24 ± 0.43 N·m/° vs. 2.28 ± 0.51 N·m/°, P < 0.05). Furthermore, the CCS + MBP constructs tolerated higher torque within a 1°–5° rotation range, underscoring their superior rotational control. Finite element analysis corroborated these findings, showing a reduced peak stress in implants with combined fixation (325.1 MPa) compared with CCS fixation (380.6 MPa), alongside mitigated stress concentrations in the femur. Stress redistribution between the plate and screws minimized localized rotational stress, thereby lowering the risks of implant fatigue and micromotion at the fracture site. These advantages are clinically significant for preventing postoperative rotational instability and delayed union. Ultimate load testing further demonstrated that the CCS + MBP group achieved a significantly higher failure load than the CCS group (2523.08 ± 432.71 N vs. 1567.88 ± 209.96 N, P < 0.05), indicating superior load-bearing capacity. A higher failure threshold implies improved fatigue resistance and mechanical safety during early mobilization and progressive weight-bearing, reducing the likelihood of complications such as screw cut-out or plate deformation. This biomechanical benefit provides a solid rationale for early ambulation and functional recovery, particularly in younger patients. The consistency between this study’s cadaveric experiments and finite element simulations reinforces the reliability of the findings. The finite element model demonstrated that combined plating reduced maximum fragment displacement (1.33 mm vs. 1.77 mm), femoral peak stress (119.6 MPa vs. 152.3 MPa), and implant peak stress (325.1 MPa vs. 380.6 MPa), confirming the MBP’s role in minimizing stress concentration and optimizing load distribution. Additionally, our retrospective analysis of 27 Pauwels type III fracture cases treated with CCS + MBP fixation reported a 92.6% union rate and 96% excellent hip function rate, highlighting its clinical feasibility and efficacy. The innovations of this study include: (1) combining cadaveric biomechanical testing with three-dimensional finite element analysis to comprehensively evaluate the macro- and micro-mechanical advantages of CCS + MBP fixation, and (2) providing failure load data to support early weight-bearing protocols. However, several limitations remain: (1) muscle, ligament, and soft tissue effects were not simulated; (2) the fracture model was simplified and did not represent comminuted patterns often encountered clinically; (3) cyclic loading was not performed, limiting assessment of long-term stability; and (4) the anatomical design of MBP requires further refinement. Future studies should incorporate individualized plate design, dynamic loading tests, and long-term animal experiments to enhance clinical translation of these findings. 5. Conclusion In this study, a Pauwels type III femoral neck fracture model was established to systematically compare the biomechanical performance of different internal fixation strategies in terms of axial stiffness, torsional stiffness, and failure load. The results demonstrated that cannulated compression screws combined with a medial buttress plate (CCS + MBP) provided significantly greater biomechanical stability than traditional three-screw fixation (CCS), exhibiting superior resistance to axial and torsional forces as well as a higher failure threshold. This construct effectively redistributes and converts vertical shear forces into compressive stresses at the fracture site, thereby creating a more favorable biomechanical environment for fracture healing. Furthermore, the combined fixation technique shows potential advantages in improving overall stability, reducing postoperative complications, and lowering the risk of nonunion and avascular necrosis of the femoral head. These findings provide important biomechanical evidence to guide surgical treatment of Pauwels type III femoral neck fractures and offer new insights for optimizing fixation strategies and implant design. Declarations Funding This study was supported by the Institutional Project (Category I) of the General Hospital of Southern Theater Command, PLA. (Grant No.2022035) Competing interests The authors declare that they have no competing interests. Country affiliation Yeqiang Luo, MS,Department of Orthopedics, General Hospital of Southern Theater Command of PLA, Guangzhou, China; Tianmo Bai, MS,Department of Orthopedics, General Hospital of Southern Theater Command of PLA, Guangzhou, China; Jingyi Wu, MS,Department of Orthopedics, General Hospital of Southern Theater Command of PLA, Guangzhou, China; Shanghui Lin, MS,Department of Orthopedics, General Hospital of Southern Theater Command of PLA, Guangzhou, China; Baofeng Li , MD, PhD, Department of Orthopedics, General Hospital of Southern Theater Command of PLA, Guangzhou, China; Corresponding author: Baofeng Li, MD, PhD* Department of Orthopedics, General Hospital of Southern Theater Command, PLA No. 111, Liuhua Avenue, Guangzhou 510010, China Email: [email protected] Author Contributions Yeqiang Luo and Tianmo Bai contributed equally to this work. Baofeng Li conceived and designed the study. Shanghui Lin and Jingyi Wu performed the experiments and data analysis. All authors read and approved the final manuscript. Ethical Approval The study protocol was approved by the Ethics Committee of the General Hospital of Southern Theater Command, PLA, and the Ethics Committee of Southern Medical University. All experiments were performed in accordance with institutional guidelines for the use of human cadaveric specimens. Consent to Publish declaration: Not applicable. Consent to Participate declaration: Not applicable. References Zhang CQ, Zhang YZ, Yu B, Zhang W, Sun H. Guidelines for the diagnosis and treatment of adult femoral neck fractures. Chin J Orthop Trauma. 2018;20(11). Rajfer RA, Carlson BA, Johnson JP. High-energy Femoral Neck Fractures in Young Patients. J Am Acad Orthop Surg. 2024;32(7):e302–12. Wang J-G, Wu J-X, Li Y-M, Xu Y-Y. Biomechanical analysis of the closed reduction internal fixation with cannulated screw of femoral neck fractures. Med (Baltim). 2021;100(8):e24834. 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Tables Table 1 Comparison of femoral neck bone mineral density (g/cm², mean ± SD) Group Femoral neck BMD (g/cm²) P -value CCS 0.723 ± 0.199 > 0.05 CCS་MBP 0.782 ± 0.164 Note : CCS = inverted triangular cannulated compression screw group; CCS + MBP = cannulated compression screw combined with medial buttress plate group. Table 2 Comparison of axial stiffness (N/mm, mean ± SD) Group Axial stiffness (N/mm) P -value CCS 171.018 ± 44.983 < 0.05 CCS་MBP 562.952 ± 88.259 Note : CCS = inverted triangular cannulated compression screw group; CCS + MBP = cannulated compression screw combined with medial buttress plate group. Table 3 Comparison of torsional stiffness (N·m/°, mean ± SD) Group Torsional stiffness (N·m/°) P -value CCS 2.278 ± 0.511 < 0.05 CCS་MBP 3.244 ± 0.427 Note : CCS = inverted triangular cannulated compression screw group; CCS + MBP = cannulated compression screw combined with medial buttress plate group. Table 4 Comparison of failure load (N, mean ± SD) Group Failure load (N) P -value CCS 1567.883 ± 209.959 < 0.05 CCS་MBP 2523.083 ± 432.707 Note : CCS = inverted triangular cannulated compression screw group; CCS + MBP = cannulated compression screw combined with medial buttress plate group. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 31 Jan, 2026 Reviews received at journal 30 Jan, 2026 Reviews received at journal 10 Jan, 2026 Reviewers agreed at journal 10 Jan, 2026 Reviews received at journal 08 Jan, 2026 Reviewers agreed at journal 05 Jan, 2026 Reviewers agreed at journal 03 Jan, 2026 Reviewers agreed at journal 03 Jan, 2026 Reviews received at journal 02 Jan, 2026 Reviewers agreed at journal 02 Jan, 2026 Reviewers invited by journal 02 Jan, 2026 Editor invited by journal 21 Dec, 2025 Editor assigned by journal 10 Oct, 2025 Submission checks completed at journal 10 Oct, 2025 First submitted to journal 28 Sep, 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-7734693","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":569076353,"identity":"ef8cf902-ee31-4c1e-81cd-11e6ccf3a273","order_by":0,"name":"Yeqiang Luo","email":"","orcid":"","institution":"General Hospital of Southern Theater Command","correspondingAuthor":false,"prefix":"","firstName":"Yeqiang","middleName":"","lastName":"Luo","suffix":""},{"id":569076355,"identity":"3ae5f06f-1fa7-44b3-9c21-fdeae9e223c4","order_by":1,"name":"Tianmo Bai","email":"","orcid":"","institution":"General Hospital of Southern Theater 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07:06:36","extension":"html","order_by":23,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":98355,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7734693/v1/056c5df2dffc52f10ba84903.html"},{"id":99498392,"identity":"462cc648-d101-4fdb-9ed5-c3b3e70af766","added_by":"auto","created_at":"2026-01-05 07:06:35","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":141337,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eProcedure for establishing the Pauwels type III femoral neck fracture model.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e(A) Marking the osteotomy line on the femoral neck at a Pauwels angle of 70° using a goniometer;\u003c/p\u003e\n\u003cp\u003e(B) Femoral neck with the completed markings;\u003c/p\u003e\n\u003cp\u003e(C) Performing osteotomy along the marked line with a band saw.\u003c/p\u003e\n\u003cp\u003e(D) Completed femoral neck fracture model.\u003c/p\u003e","description":"","filename":"Figure1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7734693/v1/db5c399e15da59b2ee023d14.jpg"},{"id":99498391,"identity":"d84ee606-ee79-401c-be55-07d45ac61a92","added_by":"auto","created_at":"2026-01-05 07:06:35","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":29777,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSchematic illustration of internal fixation placement for femoral neck fractures.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e(A, A′) Anteroposterior and lateral views of Kirschner wire placement.\u003c/p\u003e\n\u003cp\u003e(B, B′) Anteroposterior and lateral views of the inverted triangular cannulated compression screw (CCS) group.\u003c/p\u003e\n\u003cp\u003e(C, C′) Anteroposterior and lateral views of the inverted triangular CCS with medial buttress plate (MBP) group.\u003c/p\u003e","description":"","filename":"Figure2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7734693/v1/b7b9bfa06918a82643f2e46f.jpg"},{"id":99790394,"identity":"56c85299-934c-4813-84d6-b876ccea66f4","added_by":"auto","created_at":"2026-01-08 12:58:01","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":21530,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSchematic of distal femur fixation and preparation for biomechanical testing.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Figure3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7734693/v1/7ff375b753ecb2c97ae39087.jpg"},{"id":99498400,"identity":"50f5d3bc-86b6-40ff-ae39-ee52852bc1f4","added_by":"auto","created_at":"2026-01-05 07:06:35","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":27157,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eBiomechanical testing protocol for femoral neck fracture models.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e(A) Axial compression test; (B) Torsional test; (C) Failure test;\u003c/p\u003e","description":"","filename":"Figure4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7734693/v1/25516c6981c2d028c3ab07cd.jpg"},{"id":99790730,"identity":"3722c861-2513-432a-bfcc-e19c9cb0c622","added_by":"auto","created_at":"2026-01-08 12:58:38","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":17067,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eLoad–displacement curves of the CCS group and the CCS+MBP group under 100–700 N axial loading.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Figure5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7734693/v1/f6ab58de0f21e4825bc1d5d4.jpg"},{"id":99498398,"identity":"a36ff19a-35f1-4fc0-9672-4bd7cedc606f","added_by":"auto","created_at":"2026-01-05 07:06:35","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":14612,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eTorque–angle curves of the CCS group and the CCS+MBP group.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Figure6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7734693/v1/ed590f0e38a9d54e3aa29dee.jpg"},{"id":99802894,"identity":"8b56a2c0-29b2-4dbf-a493-98d86fc50b3f","added_by":"auto","created_at":"2026-01-08 14:08:58","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1231567,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7734693/v1/1ecb47ce-1365-40d3-8f2b-560faca6b066.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Biomechanical Study of Medial Buttress Plate Combined with Cannulated Compression Screws for Pauwels Type III Femoral Neck Fractures Using Cadaveric Specimens","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eFemoral neck fracture (FNF) is a common type of hip fracture, accounting for approximately 3.6% of all fractures and 57% of hip fractures[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e].In recent years, with the aging population and the increasing incidence of traffic accidents, the prevalence of FNF has been rising, and the proportion of younger patients is gradually increasing. In this population, FNFs are often caused by high-energy trauma and typically present as vertical, unstable Pauwels type III fractures[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eCurrently, internal fixation techniques for vertically unstable FNFs include cannulated compression screws (CCS), dynamic hip screws (DHS), femoral neck system (FNS), and proximal femoral locking plates (PFLP) [\u003cspan additionalcitationids=\"CR4\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Among these, the inverted triangle CCS configuration is widely used for treating FNFs in young and middle-aged adults due to its minimally invasive approach, technical simplicity, and reliable fixation[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].However, Pauwels type III fractures (Pauwels angle\u0026thinsp;\u0026gt;\u0026thinsp;50\u0026deg;) feature a near-vertical fracture line subjected to substantial shear forces. CCS alone often fails to provide sufficient angular stability and resistance to shear stress, leading to complications such as implant loosening and secondary fracture displacement[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eTo address these challenges, the combination of a medial buttress plate (MBP) placed anteroinferior to the fracture line with an inverted triangle CCS configuration has been proposed to improve resistance to vertical shear forces. Studies have shown that this construct not only reduces the incidence of varus collapse but also converts detrimental shear forces into compressive stress that facilitates fracture healing, thereby optimizing the biomechanical environment[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Previous finite element analyses and clinical follow-up studies have demonstrated favorable biomechanical performance and clinical outcomes of the CCS\u0026thinsp;+\u0026thinsp;MBP construct in Pauwels type III FNFs[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. However, direct biomechanical validation of this fixation strategy using cadaveric models remains limited.\u003c/p\u003e \u003cp\u003eBuilding upon prior findings, this study employed fresh adult femoral specimens to establish Pauwels type III FNF models and compared the fixation performance of CCS\u0026thinsp;+\u0026thinsp;MBP with CCS alone in vertically unstable fractures. The goal was to provide experimental evidence to guide the optimization of treatment strategies for Pauwels type III FNFs.\u003c/p\u003e"},{"header":"2. Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Specimen preparation\u003c/h2\u003e \u003cp\u003eA total of 12 adult femoral specimens was obtained from the Department of Anatomy, Southern Medical University. All specimens were sourced from voluntarily donated, embalmed cadavers. Pre-experimental radiographic examinations confirmed the absence of fractures, tumors, or other pathological changes. Bone mineral density (BMD) was measured using dual-energy X-ray absorptiometry (DXA), and no statistically significant differences in BMD were found among specimens. The study protocol was approved by the Ethics Committee of the General Hospital of the Southern Theater Command of the People\u0026rsquo;s Liberation Army and the Ethics Committee of Southern Medical University. Specimens were thawed at room temperature for 24 hours prior to testing, and all muscles, ligaments, and soft tissues were carefully removed, preserving only the complete bony structures and joint capsules.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Experimental grouping and fracture modeling\u003c/h2\u003e \u003cp\u003eSpecimens were randomly assigned into two groups (n\u0026thinsp;=\u0026thinsp;6 each) using a computer-generated random number table:\u003c/p\u003e \u003cp\u003e \u003col\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eCannulated compression screw group (CCS)\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eCannulated compression screw combined with medial buttress plate group (CCS\u0026thinsp;+\u0026thinsp;MBP).\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003c/ol\u003e \u003c/p\u003e \u003cp\u003ePauwels type III femoral neck fracture models were created following the method described by Markus et al.[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. A horizontal osteotomy was performed at the distal femur to standardize specimen length. The osteotomy angle was measured and marked using a goniometer, and a precision oscillating saw was used to create the fracture. The osteotomy started at the proximal femoral neck near the femoral head and extended downward at a 70\u0026deg; Pauwels angle to the femoral neck base, forming a 20\u0026deg; angle with the femoral shaft axis to simulate a typical Pauwels type III vertically unstable fracture (\u003cb\u003eFig.\u0026nbsp;1\u003c/b\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Internal fixation technique\u003c/h2\u003e \u003c/div\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003ePilot drilling:\u003c/em\u003e\u003c/strong\u003ePrior to osteotomy, under fluoroscopic guidance, pilot drilling for screw channels was performed to ensure anatomical reduction and consistent screw trajectory. Kirschner wires were inserted 3\u0026ndash;5 cm below the greater trochanter along the femoral neck axis, following the principles of divergence, subcortical placement, and parallelism. Wire tips were positioned in the subchondral bone approximately 5 mm beneath the articular surface \u003cstrong\u003e(Fig. 2A\u003c/strong\u003e).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eCCS group:\u003c/em\u003e\u003c/strong\u003eThree 7.3-mm cannulated compression screws were inserted in an inverted triangle configuration. The inferior screw was placed through the calcar to provide vertical support, while the other two screws were positioned anteriorly and posteriorly along the femoral neck cortex, with their tips approximately 5 mm from the subchondral bone (\u003cstrong\u003eFig. 2B\u003c/strong\u003e).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eCCS+MBP group:\u003c/em\u003e\u003c/strong\u003eThe screw placement was identical to the CCS group, with the addition of a one-third tubular medial buttress plate on the medial femoral neck, secured with three cortical screws. The plate was positioned slightly proximal to the fracture line to enhance medial support and overall construct stability (\u003cstrong\u003eFig. 2C\u003c/strong\u003e).\u003c/p\u003e\n\u003cp\u003eTo avoid malreduction caused by plate placement prior to osteotomy, the plate was applied after fracture creation. All fixation procedures were performed by the same senior orthopedic surgeon and verified with fluoroscopy for anatomical reduction.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.4 Specimen mounting\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTo ensure specimen stability during biomechanical testing and simulate the load-bearing condition of single-leg stance, the distal femur was embedded in a custom base to maintain consistent positioning. The distal femur was trimmed to 40 cm in length. A self-curing dental acrylic resin mixture was poured into a custom mold, and the distal femur was inserted in a neutral sagittal position, with 15\u0026deg; adduction in the coronal plane and sagittal alignment to mimic single-leg stance. A custom jig was used to secure the femur, and specimens were left to cure at room temperature for approximately 30 minutes to achieve rigid fixation. This method effectively prevented specimen movement or displacement during testing, ensuring accuracy and reproducibility (\u003cstrong\u003eFig. 3\u003c/strong\u003e).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.5 Biomechanical testing\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eBiomechanical tests were conducted using a Bose ElectroForce 3510 testing system:\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eAxial compression test:\u003c/em\u003e\u003c/strong\u003eEach specimen was preloaded to 100 N five times to eliminate initial gaps and material creep. Vertical loading was then applied at a rate of 20 N/s until reaching 700 N to simulate the maximal physiological load during single-leg stance. Displacement was recorded in real time, and load\u0026ndash;displacement curves were plotted. Axial stiffness was calculated from the slope of the linear portion of the curve (\u003cstrong\u003eFig. 4A\u003c/strong\u003e).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eTorsional stiffness test:\u003c/em\u003e\u003c/strong\u003e Each specimen was preconditioned with five cycles of 3\u0026deg; torsion, followed by torsional loading at a rate of 0.5\u0026deg;/s up to 5\u0026deg;. Torque\u0026ndash;angle curves were generated, and torsional stiffness was determined from the slope. Throughout testing, specimens were kept moist with saline spray to maintain their biomechanical properties (\u003cstrong\u003eFig. 4B\u003c/strong\u003e).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eFailure test:\u003c/em\u003e\u003c/strong\u003e Specimens were returned to their initial position and vertically loaded until construct failure. Failure was defined as:\u003c/p\u003e\n\u003col start=\"1\" type=\"1\"\u003e\n \u003cli\u003eA sudden drop in the load\u0026ndash;displacement curve;\u003c/li\u003e\n \u003cli\u003eNew fracture lines or displacement of fracture fragments;\u003c/li\u003e\n \u003cli\u003eFracture-end displacement \u0026gt;10 mm;\u003c/li\u003e\n \u003cli\u003eScrew loosening or plate deformation;\u003c/li\u003e\n \u003cli\u003eImplant fracture or detachment from bone.\u003c/li\u003e\n\u003c/ol\u003e\n\u003cp\u003eFailure load was recorded as the ultimate load-bearing capacity of the construct (\u003cstrong\u003eFig. 4C\u003c/strong\u003e).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.6 Statistical analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll data were analyzed using SPSS software. Continuous variables are presented as mean \u0026plusmn; standard deviation (SD) and compared using independent-samples t-tests. Categorical variables are presented as percentages and analyzed with the \u0026chi;\u0026sup2; test or corrected \u0026chi;\u0026sup2; test. A \u003cem\u003eP\u003c/em\u003e value of \u0026lt;0.05 was considered statistically significant.\u003c/p\u003e"},{"header":"3. Results","content":"\u003cp\u003eThis study compared femoral neck bone mineral density (BMD), axial stiffness, torsional stiffness, and failure load between the CCS group and CCS\u0026thinsp;+\u0026thinsp;MBP group. No significant difference in BMD was found between groups (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05), ensuring comparability of baseline conditions. The CCS\u0026thinsp;+\u0026thinsp;MBP construct demonstrated significantly higher axial stiffness, torsional stiffness, and failure load compared with CCS alone (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05), indicating superior overall stability in Pauwels type III femoral neck fractures. Detailed results are presented below.\u003c/p\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Bone mineral density\u003c/h2\u003e \u003cp\u003eBMD of the femoral neck was measured using dual-energy X-ray absorptiometry (DXA). The mean BMD was 0.723\u0026thinsp;\u0026plusmn;\u0026thinsp;0.199 g/cm\u0026sup2; in the CCS group and 0.782\u0026thinsp;\u0026plusmn;\u0026thinsp;0.164 g/cm\u0026sup2; in the CCS\u0026thinsp;+\u0026thinsp;MBP group, with no statistically significant difference between groups (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05) (\u003cb\u003eTable\u0026nbsp;1\u003c/b\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Axial stiffness\u003c/h2\u003e \u003cp\u003eLoad\u0026ndash;displacement curves from axial compression tests exhibited linear characteristics in both groups (\u003cb\u003eFig.\u0026nbsp;5\u003c/b\u003e). The mean axial stiffness was 171.02\u0026thinsp;\u0026plusmn;\u0026thinsp;44.98 N/mm in the CCS group and 562.95\u0026thinsp;\u0026plusmn;\u0026thinsp;88.26 N/mm in the CCS\u0026thinsp;+\u0026thinsp;MBP group (\u003cb\u003eTable\u0026nbsp;2\u003c/b\u003e). Statistical analysis showed a significantly higher axial stiffness in the CCS\u0026thinsp;+\u0026thinsp;MBP group compared with the CCS group (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e3.3 Torsional stiffness\u003c/h2\u003e \u003cp\u003eTorque\u0026ndash;angle curves obtained from torsional tests were linear in both groups (\u003cb\u003eFig.\u0026nbsp;6\u003c/b\u003e). The mean torsional stiffness was 2.28\u0026thinsp;\u0026plusmn;\u0026thinsp;0.51 N\u0026middot;m/\u0026deg; in the CCS group and 3.24\u0026thinsp;\u0026plusmn;\u0026thinsp;0.43 N\u0026middot;m/\u0026deg; in the CCS\u0026thinsp;+\u0026thinsp;MBP group (\u003cb\u003eTable\u0026nbsp;3\u003c/b\u003e). The CCS\u0026thinsp;+\u0026thinsp;MBP group demonstrated significantly greater torsional stiffness than the CCS group (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Within the torsion range of 1\u0026deg;\u0026ndash;5\u0026deg;, torque values in the CCS\u0026thinsp;+\u0026thinsp;MBP group were consistently higher than those in the CCS group (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e3.4 Failure load\u003c/h2\u003e \u003cp\u003eFailure testing showed that the mean failure load was 1567.88\u0026thinsp;\u0026plusmn;\u0026thinsp;209.96 N in the CCS group and 2523.08\u0026thinsp;\u0026plusmn;\u0026thinsp;432.71 N in the CCS\u0026thinsp;+\u0026thinsp;MBP group (\u003cb\u003eTable\u0026nbsp;4\u003c/b\u003e). The difference between groups was statistically significant (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05), indicating that the CCS\u0026thinsp;+\u0026thinsp;MBP construct provides superior stability under high load conditions compared with CCS alone.\u003c/p\u003e \u003c/div\u003e"},{"header":"4. Discussion","content":"\u003cp\u003eFemoral neck fractures are a common yet severe injury in trauma orthopedics, with an increasing incidence due to population aging, and they remain a major cause of disability and mortality. In young and middle-aged patients, femoral neck fractures are typically caused by high-energy trauma, such as traffic accidents or falls from height. Pauwels type III fractures, characterized by a nearly vertical fracture line, are particularly challenging to manage due to significantly increased shear stress at the femoral neck and the high technical demands of internal fixation[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan additionalcitationids=\"CR13\" citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Studies have reported complication rates as high as 45% for high-energy femoral neck fractures, with common complications including nonunion, avascular necrosis of the femoral head, and impaired hip function[\u003cspan additionalcitationids=\"CR16\" citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Thus, achieving accurate anatomic reduction, ensuring rigid and reliable fixation, and reducing complication rates remain key challenges in treating these injuries in physiologically young patients.\u003c/p\u003e \u003cp\u003eFor displaced femoral neck fractures in elderly patients, arthroplasty is the preferred treatment, whereas anatomic reduction followed by stable internal fixation remains the gold standard in younger individuals[\u003cspan additionalcitationids=\"CR19\" citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Current fixation methods include the inverted triangular configuration of three cannulated compression screws (CCS), dynamic hip screw (DHS), and femoral neck system (FNS). CCS fixation is widely used due to its minimally invasive nature, ease of operation, and satisfactory stability. However, its shear and rotational resistance are limited in Pauwels type III fractures, often leading to screw loosening and redisplacement of the fracture[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. DHS is anatomically compatible with the proximal femur and provides excellent axial compression and stability[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Nonetheless, its rotational stability is inadequate, and the insertion of a large lag screw may compromise residual vascular supply, increasing the risk of avascular necrosis[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. FNS, a novel minimally invasive system, offers multidirectional stability while minimizing bone loss, and studies have shown that it reduces postoperative complications and improves union rates in Pauwels type III fractures, though large-scale studies are needed to validate long-term outcomes[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. Recently, scholars have proposed augmenting the inverted triangular CCS configuration with a medial buttress plate (MBP) to enhance shear resistance and optimize stress distribution[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan additionalcitationids=\"CR28\" citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. The MBP converts vertical shear forces into compressive forces across the fracture site, thereby creating a more favorable biomechanical environment for healing and offering a promising strategy for stabilizing Pauwels type III fractures.\u003c/p\u003e \u003cp\u003eBased on a thorough review of the strengths and weaknesses of current fixation techniques, this study established Pauwels type III fracture models in cadaveric femora to compare the biomechanical performance of CCS alone and CCS combined with MBP. Experimental evaluation of key parameters\u0026mdash;including axial stiffness, torsional stiffness, and failure load\u0026mdash;demonstrated that the addition of MBP significantly improves the overall stability of fixation constructs.\u003c/p\u003e \u003cp\u003eIn axial compression testing, the CCS\u0026thinsp;+\u0026thinsp;MBP group exhibited significantly greater mean axial stiffness than the CCS group (562.95\u0026thinsp;\u0026plusmn;\u0026thinsp;88.26 N/mm vs. 171.02\u0026thinsp;\u0026plusmn;\u0026thinsp;44.98 N/mm, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05), suggesting that medial plating markedly enhances vertical stability. This effect can be attributed to the plate\u0026rsquo;s \u0026ldquo;buttress\u0026rdquo; function along the medial cortex, which transfers part of the axial load from the screw\u0026ndash;trabecular bone interface to the plate\u0026ndash;cortical bone contact interface, effectively transforming shear forces into compressive stresses conducive to healing. This tripod-like load-sharing structure reduces micromotion at the fracture site and supports early weight-bearing and rehabilitation. In contrast, CCS fixation relies solely on interscrew friction and cancellous bone support, which are insufficient for vertically oriented fractures, resulting in a higher risk of construct instability.\u003c/p\u003e \u003cp\u003eThe torsional tests revealed that torsional stiffness was significantly higher in the CCS\u0026thinsp;+\u0026thinsp;MBP group than in the CCS group (3.24\u0026thinsp;\u0026plusmn;\u0026thinsp;0.43 N\u0026middot;m/\u0026deg; vs. 2.28\u0026thinsp;\u0026plusmn;\u0026thinsp;0.51 N\u0026middot;m/\u0026deg;, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Furthermore, the CCS\u0026thinsp;+\u0026thinsp;MBP constructs tolerated higher torque within a 1\u0026deg;\u0026ndash;5\u0026deg; rotation range, underscoring their superior rotational control. Finite element analysis corroborated these findings, showing a reduced peak stress in implants with combined fixation (325.1 MPa) compared with CCS fixation (380.6 MPa), alongside mitigated stress concentrations in the femur. Stress redistribution between the plate and screws minimized localized rotational stress, thereby lowering the risks of implant fatigue and micromotion at the fracture site. These advantages are clinically significant for preventing postoperative rotational instability and delayed union.\u003c/p\u003e \u003cp\u003eUltimate load testing further demonstrated that the CCS\u0026thinsp;+\u0026thinsp;MBP group achieved a significantly higher failure load than the CCS group (2523.08\u0026thinsp;\u0026plusmn;\u0026thinsp;432.71 N vs. 1567.88\u0026thinsp;\u0026plusmn;\u0026thinsp;209.96 N, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05), indicating superior load-bearing capacity. A higher failure threshold implies improved fatigue resistance and mechanical safety during early mobilization and progressive weight-bearing, reducing the likelihood of complications such as screw cut-out or plate deformation. This biomechanical benefit provides a solid rationale for early ambulation and functional recovery, particularly in younger patients.\u003c/p\u003e \u003cp\u003eThe consistency between this study\u0026rsquo;s cadaveric experiments and finite element simulations reinforces the reliability of the findings. The finite element model demonstrated that combined plating reduced maximum fragment displacement (1.33 mm vs. 1.77 mm), femoral peak stress (119.6 MPa vs. 152.3 MPa), and implant peak stress (325.1 MPa vs. 380.6 MPa), confirming the MBP\u0026rsquo;s role in minimizing stress concentration and optimizing load distribution. Additionally, our retrospective analysis of 27 Pauwels type III fracture cases treated with CCS\u0026thinsp;+\u0026thinsp;MBP fixation reported a 92.6% union rate and 96% excellent hip function rate, highlighting its clinical feasibility and efficacy.\u003c/p\u003e \u003cp\u003eThe innovations of this study include: (1) combining cadaveric biomechanical testing with three-dimensional finite element analysis to comprehensively evaluate the macro- and micro-mechanical advantages of CCS\u0026thinsp;+\u0026thinsp;MBP fixation, and (2) providing failure load data to support early weight-bearing protocols. However, several limitations remain: (1) muscle, ligament, and soft tissue effects were not simulated; (2) the fracture model was simplified and did not represent comminuted patterns often encountered clinically; (3) cyclic loading was not performed, limiting assessment of long-term stability; and (4) the anatomical design of MBP requires further refinement. Future studies should incorporate individualized plate design, dynamic loading tests, and long-term animal experiments to enhance clinical translation of these findings.\u003c/p\u003e"},{"header":"5. Conclusion","content":"\u003cp\u003eIn this study, a Pauwels type III femoral neck fracture model was established to systematically compare the biomechanical performance of different internal fixation strategies in terms of axial stiffness, torsional stiffness, and failure load. The results demonstrated that cannulated compression screws combined with a medial buttress plate (CCS\u0026thinsp;+\u0026thinsp;MBP) provided significantly greater biomechanical stability than traditional three-screw fixation (CCS), exhibiting superior resistance to axial and torsional forces as well as a higher failure threshold. This construct effectively redistributes and converts vertical shear forces into compressive stresses at the fracture site, thereby creating a more favorable biomechanical environment for fracture healing. Furthermore, the combined fixation technique shows potential advantages in improving overall stability, reducing postoperative complications, and lowering the risk of nonunion and avascular necrosis of the femoral head. These findings provide important biomechanical evidence to guide surgical treatment of Pauwels type III femoral neck fractures and offer new insights for optimizing fixation strategies and implant design.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eFunding\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was supported by the Institutional Project (Category I) of the General Hospital of Southern Theater Command, PLA. (Grant No.2022035)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCountry affiliation\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eYeqiang Luo,\u0026nbsp;\u003c/strong\u003eMS,Department of Orthopedics, General Hospital of Southern Theater Command of PLA, Guangzhou, China;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTianmo Bai,\u0026nbsp;\u003c/strong\u003eMS,Department of Orthopedics, General Hospital of Southern Theater Command of PLA, Guangzhou, China;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eJingyi Wu,\u0026nbsp;\u003c/strong\u003eMS,Department of Orthopedics, General Hospital of Southern Theater Command of PLA, Guangzhou, China;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eShanghui Lin,\u0026nbsp;\u003c/strong\u003eMS,Department of Orthopedics, General Hospital of Southern Theater Command of PLA, Guangzhou, China;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eBaofeng Li\u003c/strong\u003e, MD, PhD, Department of Orthopedics, General Hospital of Southern Theater Command of PLA, Guangzhou, China;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCorresponding author:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eBaofeng Li, MD, PhD*\u003c/p\u003e\n\u003cp\u003eDepartment of Orthopedics, General Hospital of Southern Theater Command, PLA\u003c/p\u003e\n\u003cp\u003eNo. 111, Liuhua Avenue, Guangzhou 510010, China\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEmail:\u0026nbsp;\u003c/strong\[email protected]\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eYeqiang Luo and Tianmo Bai contributed equally to this work.\u003c/p\u003e\n\u003cp\u003eBaofeng Li conceived and designed the study. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eShanghui Lin and Jingyi Wu performed the experiments and data analysis. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAll authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical Approval\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study protocol was approved by the Ethics Committee of the General Hospital of Southern Theater Command, PLA, and the Ethics Committee of Southern Medical University. All experiments were performed in accordance with institutional guidelines for the use of human cadaveric specimens.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to Publish declaration:\u003c/strong\u003e Not applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to Participate declaration:\u0026nbsp;\u003c/strong\u003eNot applicable.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eZhang CQ, Zhang YZ, Yu B, Zhang W, Sun H. Guidelines for the diagnosis and treatment of adult femoral neck fractures. Chin J Orthop Trauma. 2018;20(11).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRajfer RA, Carlson BA, Johnson JP. High-energy Femoral Neck Fractures in Young Patients. J Am Acad Orthop Surg. 2024;32(7):e302\u0026ndash;12.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang J-G, Wu J-X, Li Y-M, Xu Y-Y. Biomechanical analysis of the closed reduction internal fixation with cannulated screw of femoral neck fractures. Med (Baltim). 2021;100(8):e24834.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRamadanov N, J\u0026oacute;źwiak K, Hauptmann M, Lazaru P, Marinova-Kichikova P, Dimitrov D, Becker R. Cannulated screws versus dynamic hip screw versus hemiarthroplasty versus total hip arthroplasty in patients with displaced and non-displaced femoral neck fractures: a systematic review and frequentist network meta-analysis of 5703 patients. J Orthop Surg Res. 2023;18(1):625.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJiang J, Chen J, Xing F, Liu H, Xiang Z. Comparison of femoral neck system versus cannulated screws for treatment of femoral neck fractures: a systematic review and meta-analysis. BMC Musculoskelet Disord. 2023;24(1):285.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang R-Y, Li J-T, Zhao J-X, Zhao Z, Zhang L-C, Yun C, Su X-Y, Tang P-F. Comparison of oblique triangular configuration and inverted equilateral triangular configuration of three cannulated screws in treating unstable femoral neck fracture: A finite element analysis. Injury. 2022;53(2):353\u0026ndash;61.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhong Z, Lan X, Xiang Z, Duan X. Femoral neck system and cannulated compression screws in the treatment of non-anatomical reduction Pauwels type-III femoral neck fractures: A finite element analysis. Clin Biomech (Bristol). 2023;108:106060.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMcGarry L, Rotaru J, Gunaratne R, Hickey I. Medial buttress plate use in neck of femur fracture fixations: A systematic review. Injury. 2025;56(2):112160.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLin S, Li J, Wang R, Ou Y, Jia Z, Zhang Y, Xia H, Li B, Chen B. The effect of anteromedial support plate with three cannulated screws in the treatment of Pauwels type III femoral neck fracture in young adults. Eur J Trauma Emerg Surg. 2022;48(5):4011\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLin SH. Finite element analysis of modified medial buttress plate combined with cannulated screws for Pauwels type III femoral neck fractures. Southern Medical University; 2023.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWindolf M, Braunstein V, Dutoit C, Schwieger K. Is a helical shaped implant a superior alternative to the Dynamic Hip Screw for unstable femoral neck fractures? A biomechanical investigation. Clin Biomech (Bristol). 2009;24(1):59\u0026ndash;64.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSeeley MA, Georgiadis AG, Sankar WN. Hip Vascularity: A Review of the Anatomy and Clinical Implications. J Am Acad Orthop Surg. 2016;24(8):515\u0026ndash;26.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTornetta P, Kain MSH, Creevy WR. Diagnosis of femoral neck fractures in patients with a femoral shaft fracture. Improvement with a standard protocol. J Bone Joint Surg Am. 2007;89(1):39\u0026ndash;43.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRogers NB, Achor TS, Kumaravel M, Gary JL, Munz JW, Choo AM, Routt ML, Warner SJ. Implementation of a novel MRI protocol for diagnosing femoral neck fractures in high energy femoral shaft fractures: One year results. Injury. 2021;52(8):2390\u0026ndash;4.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJohnson JP, Kleiner J, Goodman AD, Gil JA, Daniels AH, Hayda RA. Treatment of femoral neck fractures in patients 45\u0026ndash;64 years of age. Injury. 2019;50(3):708\u0026ndash;12.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCollinge CA, Finlay A, Rodriguez-Buitrago A, Beltran MJ, Mitchell PM, Mir HR, Gardner MJ, Archdeacon MT, Tornetta P. Treatment Failure in Femoral Neck Fractures in Adults Less Than 50 Years of Age: Analysis of 492 Patients Repaired at 26 North American Trauma Centers. J Orthop Trauma. 2022;36(6):271\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLu Y, Uppal HS. Hip Fractures: Relevant Anatomy, Classification, and Biomechanics of Fracture and Fixation. Geriatr Orthop Surg Rehabil. 2019;10:2151459319859139.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eQiu L, Huang Y, Li G, Wu H, Zhang Y, Zhang Z. Essential role of reliable reduction quality in internal fixation of femoral neck fractures in the non-elderly patients-a propensity score matching analysis. BMC Musculoskelet Disord. 2022;23(1):346.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHalvorson J. Reduction Techniques for Young Femoral Neck Fractures. J Orthop Trauma. 2019;33(Suppl 1):S12\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGhayoumi P, Kandemir U, Morshed S. Evidence based update: open versus closed reduction. Injury. 2015;46(3):467\u0026ndash;73.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWeil YA, Khoury A, Zuaiter I, Safran O, Liebergall M, Mosheiff R. Femoral neck shortening and varus collapse after navigated fixation of intracapsular femoral neck fractures. J Orthop Trauma. 2012;26(1):19\u0026ndash;23.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiporace F, Gaines R, Collinge C, Haidukewych GJ. Results of internal fixation of Pauwels type-3 vertical femoral neck fractures. J Bone Joint Surg Am. 2008;90(8):1654\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCullen SE, Sephton B, Malik I, Aldarragi A, Crossdale M, O'Connor M. A Comparative Study of Dynamic Hip Screw Versus Multiple Cannulated Compression Screw Fixation in Undisplaced Intracapsular Neck of Femur Fractures. Cureus. 2022;14(11):e31619.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eXia Y, Zhang W, Zhang Z, Wang J, Yan L. Treatment of femoral neck fractures: sliding hip screw or cannulated screws? A meta-analysis. J Orthop Surg Res. 2021;16(1):54.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMoon J-K, Lee JI, Hwang K-T, Yang J-H, Park Y-S, Park K-C. Biomechanical comparison of the femoral neck system and the dynamic hip screw in basicervical femoral neck fractures. Sci Rep. 2022;12(1):7915.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLin H, Lai C, Zhou Z, Wang C, Yu X. Femoral Neck System vs. four cannulated screws in the treatment of Pauwels III femoral neck fracture. J Orthop Sci. 2023;28(6):1373\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHawks MA, Kim H, Strauss JE, Oliphant BW, Golden RD, Hsieh AH, Nascone JW, O'Toole RV. Does a trochanteric lag screw improve fixation of vertically oriented femoral neck fractures? A biomechanical analysis in cadaveric bone. Clin Biomech (Bristol). 2013;28(8):886\u0026ndash;91.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi J, Yin P, Zhang L, Chen H, Tang P. Medial anatomical buttress plate in treating displaced femoral neck fracture a finite element analysis. Injury. 2019;50(11):1895\u0026ndash;900.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGiordano V, Alves DD, Paes RP, Amaral AB, Giordano M, Belangero W, Freitas A, Koch HA, do Amaral NP. The role of the medial plate for Pauwels type III femoral neck fracture: a comparative mechanical study using two fixations with cannulated screws. J Exp Orthop. 2019;6(1):18.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Tables","content":" \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 \u003cdiv class=\"SimplePara\"\u003eComparison of femoral neck bone mineral density (g/cm\u0026sup2;, mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD)\u003c/div\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\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003eGroup\u003c/div\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003eFemoral neck BMD (g/cm\u0026sup2;)\u003c/div\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Italic\" class=\"Italic\" name=\"Emphasis\"\u003eP\u003c/span\u003e-value\u003c/div\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eCCS\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003e0.723\u0026thinsp;\u0026plusmn;\u0026thinsp;0.199\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u0026gt;\u0026thinsp;0.05\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eCCS་MBP\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003e0.782\u0026thinsp;\u0026plusmn;\u0026thinsp;0.164\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c3\" namest=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Italic\" class=\"Italic\" name=\"Emphasis\"\u003eNote\u003c/span\u003e: CCS\u0026thinsp;=\u0026thinsp;inverted triangular cannulated compression screw group; CCS\u0026thinsp;+\u0026thinsp;MBP\u0026thinsp;=\u0026thinsp;cannulated compression screw combined with medial buttress plate group.\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003cbr/\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 \u003cdiv class=\"SimplePara\"\u003eComparison of axial stiffness (N/mm, mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD)\u003c/div\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\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003eGroup\u003c/div\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003eAxial stiffness (N/mm)\u003c/div\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Italic\" class=\"Italic\" name=\"Emphasis\"\u003eP\u003c/span\u003e-value\u003c/div\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eCCS\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003e171.018\u0026thinsp;\u0026plusmn;\u0026thinsp;44.983\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u0026lt;\u0026thinsp;0.05\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eCCS་MBP\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003e562.952\u0026thinsp;\u0026plusmn;\u0026thinsp;88.259\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c3\" namest=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Italic\" class=\"Italic\" name=\"Emphasis\"\u003eNote\u003c/span\u003e: CCS\u0026thinsp;=\u0026thinsp;inverted triangular cannulated compression screw group; CCS\u0026thinsp;+\u0026thinsp;MBP\u0026thinsp;=\u0026thinsp;cannulated compression screw combined with medial buttress plate group.\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003cbr/\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cdiv class=\"SimplePara\"\u003eComparison of torsional stiffness (N\u0026middot;m/\u0026deg;, mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD)\u003c/div\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\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003eGroup\u003c/div\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003eTorsional stiffness (N\u0026middot;m/\u0026deg;)\u003c/div\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Italic\" class=\"Italic\" name=\"Emphasis\"\u003eP\u003c/span\u003e-value\u003c/div\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eCCS\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003e2.278\u0026thinsp;\u0026plusmn;\u0026thinsp;0.511\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u0026lt;\u0026thinsp;0.05\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eCCS་MBP\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003e3.244\u0026thinsp;\u0026plusmn;\u0026thinsp;0.427\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c3\" namest=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Italic\" class=\"Italic\" name=\"Emphasis\"\u003eNote\u003c/span\u003e: CCS\u0026thinsp;=\u0026thinsp;inverted triangular cannulated compression screw group; CCS\u0026thinsp;+\u0026thinsp;MBP\u0026thinsp;=\u0026thinsp;cannulated compression screw combined with medial buttress plate group.\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003cbr/\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cdiv class=\"SimplePara\"\u003eComparison of failure load (N, mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD)\u003c/div\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\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003eGroup\u003c/div\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003eFailure load (N)\u003c/div\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Italic\" class=\"Italic\" name=\"Emphasis\"\u003eP\u003c/span\u003e-value\u003c/div\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eCCS\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003e1567.883\u0026thinsp;\u0026plusmn;\u0026thinsp;209.959\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u0026lt;\u0026thinsp;0.05\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eCCS་MBP\u003c/span\u003e\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cdiv class=\"SimplePara\"\u003e2523.083\u0026thinsp;\u0026plusmn;\u0026thinsp;432.707\u003c/div\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c3\" namest=\"c1\"\u003e \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Italic\" class=\"Italic\" name=\"Emphasis\"\u003eNote\u003c/span\u003e: CCS\u0026thinsp;=\u0026thinsp;inverted triangular cannulated compression screw group; CCS\u0026thinsp;+\u0026thinsp;MBP\u0026thinsp;=\u0026thinsp;cannulated compression screw combined with medial buttress plate group.\u003c/div\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003cbr/\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-musculoskeletal-disorders","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bmsd","sideBox":"Learn more about [BMC Musculoskeletal Disorders](http://bmcmusculoskeletdisord.biomedcentral.com/)","snPcode":"","submissionUrl":"https://author-welcome.nature.com/12891","title":"BMC Musculoskeletal Disorders","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Femoral neck fracture, Pauwels type III, Cannulated compression screw, Medial buttress plate, Biomechanics","lastPublishedDoi":"10.21203/rs.3.rs-7734693/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7734693/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003ePurpose\u003c/h2\u003e \u003cp\u003eTo investigate the biomechanical advantages of medial buttress plate (MBP) combined with inverted triangle cannulated compression screws (CCS) in the internal fixation of Pauwels type III femoral neck fractures, and to provide experimental evidence for optimizing treatment strategies for vertically unstable femoral neck fractures.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eTwelve adult embalmed femoral specimens were used to create Pauwels type III femoral neck fracture models and randomly assigned to two groups: CCS group and CCS\u0026thinsp;+\u0026thinsp;MBP group (n\u0026thinsp;=\u0026thinsp;6 each). After standardized internal fixation procedures, axial compression, torsional stiffness, and failure load were tested using a Bose ElectroForce 3510 biomechanical testing system, and all measurements were recorded. Differences between groups were analyzed with independent-samples t-tests, with statistical significance set at \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eCompared with the CCS group, the CCS\u0026thinsp;+\u0026thinsp;MBP group demonstrated significantly higher axial stiffness (562.95\u0026thinsp;\u0026plusmn;\u0026thinsp;88.26 N/mm vs. 171.02\u0026thinsp;\u0026plusmn;\u0026thinsp;44.98 N/mm), torsional stiffness (3.24\u0026thinsp;\u0026plusmn;\u0026thinsp;0.43 N\u0026middot;m/\u0026deg; vs. 2.28\u0026thinsp;\u0026plusmn;\u0026thinsp;0.51 N\u0026middot;m/\u0026deg;), and failure load (2523.08\u0026thinsp;\u0026plusmn;\u0026thinsp;432.71 N vs. 1567.88\u0026thinsp;\u0026plusmn;\u0026thinsp;209.96 N) (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05 for all).\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eThe combination of MBP and CCS provides significantly greater mechanical stability than CCS alone in Pauwels type III femoral neck fractures. This construct disperses shear forces, improves the biomechanical environment for fracture healing, and may reduce postoperative complications and implant failure risk. These findings provide experimental evidence for optimizing internal fixation design and surgical strategies for vertically unstable femoral neck fractures.\u003c/p\u003e\u003ch2\u003eLevel of evidence: I\u003c/h2\u003e","manuscriptTitle":"Biomechanical Study of Medial Buttress Plate Combined with Cannulated Compression Screws for Pauwels Type III Femoral Neck Fractures Using Cadaveric Specimens","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-01-05 07:06:30","doi":"10.21203/rs.3.rs-7734693/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-01-31T20:01:46+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-30T08:46:08+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-11T01:42:20+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"38873412156530208994152354596706652934","date":"2026-01-10T14:07:45+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-08T13:19:29+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"317932338970254624564374465985697229554","date":"2026-01-05T08:15:05+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"190670017844197682438047941549231896930","date":"2026-01-04T04:53:33+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"208412416932326647340839252588435359887","date":"2026-01-03T11:12:27+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-03T01:36:04+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"8163441146803423628347721039290967497","date":"2026-01-03T01:02:24+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-01-02T12:29:04+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-12-22T04:34:50+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-10-10T10:12:56+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-10-10T10:11:48+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Musculoskeletal Disorders","date":"2025-09-28T13:23:56+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-musculoskeletal-disorders","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bmsd","sideBox":"Learn more about [BMC Musculoskeletal Disorders](http://bmcmusculoskeletdisord.biomedcentral.com/)","snPcode":"","submissionUrl":"https://author-welcome.nature.com/12891","title":"BMC Musculoskeletal Disorders","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"5dd68fbf-187a-479b-aecb-786ec514bd2b","owner":[],"postedDate":"January 5th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-04-28T13:40:33+00:00","versionOfRecord":[],"versionCreatedAt":"2026-01-05 07:06:30","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7734693","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7734693","identity":"rs-7734693","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}