Ipsilateral Femoral Neck Fracture Rates Following Ballistic Fractures of the Femoral Shaft

Ipsilateral Femoral Neck Fracture Rates Following Ballistic Fractures of the Femoral Shaft | 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 Ipsilateral Femoral Neck Fracture Rates Following Ballistic Fractures of the Femoral Shaft Clayton Welsh, Michael McGraw, Matthew Todd, Colin Cantrell, Bennet Butler This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9335057/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 Introduction: Prior literature demonstrates that in patients with blunt femoral shaft fractures, ipsilateral femoral neck fractures occur at a rate of 1-9% and can be challenging to diagnose. Ballistic fractures of the femoral shaft remain an area of ongoing research, with little evidence examining whether these fractures also carry an increased risk of ipsilateral femoral neck fracture. The purpose of this study is to evaluate the incidence of concurrent ipsilateral femoral neck and femoral shaft fractures after ballistic injuries. Methods: We performed a retrospective review of ballistic diaphyseal femur fractures treated with operative fixation in adult. Operative reports, X-ray (XR), and computed tomography (CT) images were utilized to assess for ipsilateral femoral neck fractures diagnosed at the time of injury, intra-operatively, or post-operatively. Results: The study included 77 patients who sustained ballistic fractures of the femoral diaphysis. 94% of fractures were classified as AO/OTA 32C. Two patients (2.6%) had femoral shaft fractures with direct extension into the femoral neck identified on CT imaging. No femoral neck fractures occurred independent of the site of primary femoral shaft comminution. Conclusion: Ballistic fractures of the femoral shaft carry a low risk of ipsilateral femoral neck involvement. Understanding the incidence of femoral neck involvement is a crucial component in diagnosing and treating these injuries. Level of Evidence: Level 4 Orthopaedic Trauma Fracture Femoral Shaft Femoral Neck Figures Figure 1 Figure 2 Figure 3 1. Introduction Femoral shaft fractures often occur concurrently with injuries to both the axial and appendicular skeleton, and ipsilateral fractures of the femoral neck occur in 1% to 9% of high-energy femoral shaft fractures [ 1 – 5 ]. Diagnosing a femoral neck fracture in the setting of a femoral shaft fracture can be difficult, with 20–50% of femoral neck fractures missed on injury presentation [ 1 , 2 ]. To reduce the rate of missed injuries, current imaging protocols involve dedicated pre-operative, intra-operative, and post-operative radiographs of the ipsilateral hip as well as a pre-operative computed tomography (CT) scan with two-millimeter slices through the femoral neck [ 3 ]. Despite increased awareness, pre-operative XR and CT imaging still has poor sensitivity for diagnosing ipsilateral femoral neck fractures pattern [ 6 ]. Missed femoral neck fractures can have devastating long-term impacts, including nonunion, malunion, avascular necrosis necessitating further operations [ 7 ]. The initial research to uncover the rates of ipsilateral femoral shaft/neck fractures examined injuries of a blunt mechanism, most frequently vehicular crashes [ 2 ]. In a blunt injury, the combined femoral shaft and neck fracture is postulated to result from a longitudinal force transmitted up the femoral shaft and across a flexed and abducted hip [ 7 , 8 ]. The mechanism of a ballistic injury differs significantly, with fractures resulting from either the direct impact of a bullet striking bone or through indirect forces generated by the bullet’s energy. As a bullet travels through soft tissue, it is preceded by a shockwave that creates a temporary cavity of up to 12.5 times the diameter of the bullet [ 9 ]. The force of generated by the temporary cavity is enough to fracture bones, even without a direct impact from the bullet [ 9 , 10 ]. Whereas fractures from the direct impact of the bullet typically result in severe comminution, indirect fractures are often minimally displaced and can be more difficult to detect on plain radiographs [ 10 , 11 ]. Through either direct extension of comminution or the creation of a wide temporary cavity, ballistic fractures of the femoral shaft may have a similar association with femoral neck fractures as seen in blunt mechanisms. This study will investigate the characteristics of ballistic femoral shaft fractures and the incidence of ipsilateral femoral neck fractures. We will further investigate the efficacy of XR, CT, and intraoperative fluoroscopy in detecting femoral neck involvement. We hypothesize that there will be a similar rate of femoral neck involvement in ballistic and blunt mechanisms. 2. Methods We performed an IRB-approved retrospective review of ballistic diaphyseal femur fractures at a single level one trauma center between 2015 and 2023. Patients over the age of 18 with operatively treated femur fractures of a known ballistic mechanism were included. Pediatric patients, patients with non-operative ballistic fractures, and fractures with a primary zone of comminution in the intertrochanteric, femoral neck, supracondylar, or distal femur region were excluded. Patients were sequentially identified through consult lists, surgical schedules, and a review of the electronic medical record. All patients were admitted to the hospital as trauma activations and underwent surgical stabilization of their femur fractures with either intramedullary implants or plate and screw constructs. We recorded demographic information including age at presentation, time to surgery, and method of surgical fixation. Injury XRs and CT scans were used to classify patients according to the AO/OTA classification system for diaphyseal femur fractures. To better stratify which patients would be most at risk of femoral neck involvement, we measured the distance in millimeters (mm) from the most medial point of the lesser trochanter to the most proximal extent of direct fracture comminution on AP radiographs. (Fig. 1 ). When the primary femoral shaft fracture had direct extension above the lesser trochanter, negative values were used. In patients with available CT imaging, we performed a similar process using the most medial point of the lesser trochanter to the most proximal extent of fracture comminution (Fig. 2). Injury XRs and CT, operating room fluoroscopy, operative reports, and post-operative XRs were reviewed to note the presence of an ipsilateral femoral neck fracture. Radiographic analysis of each available injury XR and CT was performed by two reviewers to determine the injury classification and proximal extension of the femoral shaft fracture. 3. Results The study included 77 patients who sustained ballistic fractures of the femoral diaphysis. 74 of the 77 patients (95%) were male, with an average age of 28 years old (range 18–57). AO/OTA 32C was the most common fracture pattern, with 72 of 77 (94%) femoral shaft fractures being significantly comminuted (Table 1). CT imaging of the femoral neck was available for 66 of the 77 patients (86%). Table 1: AO/OTA injury classification results Two patients (2.6%) had femoral shaft fractures with direct extension into the femoral neck (Figs. 2 and 3). In each instance, the femoral neck fracture was not visible on injury XR but identified on CT imaging before operative intervention. CT imaging for both instances showed an uninterrupted fracture line from the primary zone of comminution into the femoral neck. No femoral neck fractures occurred independent of the site of primary femoral shaft comminution. No femoral neck fractures were uncovered by intra-operative and post-operative radiographs that were not seen on CT imaging prior to the OR. The average distance from the lesser trochanter to the most proximal extent of the primary site of fracture comminution was 63 millimeters (range − 34 to 236). The two fractures of the femoral neck had visible proximal extension of their shaft fractures 21 and 33 millimeters above the lesser trochanter respectively. 4. Discussion Our study addresses the rate of femoral neck involvement following ballistic diaphyseal femur fractures. Our results indicate a low rate of femoral neck involvement, with just 2.6% of patients being affected. Our incidence fits within the established 1–9% rate of combined femoral shaft and neck fractures drawn from blunt mechanisms of injury [ 1 – 5 ]. Through both direct and indirect mechanisms, ballistic fractures behave differently from blunt fractures with wide temporary zones of injury [ 10 ]. As opposed to axial force transmission along the femoral shaft in blunt mechanisms, our data showed the ballistic mechanism of a combined shaft and neck fracture is due to direct extension of the fracture into the neck. In an additional study on combined ballistic femoral neck and shaft fractures, Baker et. al examined ballistic femur fractures in 68 patients and compared them to a blunt cohort [ 12 ]. In this series, femoral neck fractures were seen in 5.8% of patients with no difference in femoral neck fracture rates between blunt and ballistic injury mechanisms. In three of the four instances reported by Baker et. al, femoral neck fractures were caused by a direct propagation of fracture lines across the intertrochanteric region with only one instance of a non-contiguous femoral neck fracture identified through CT imaging [ 12 ]. Overall, our study demonstrates rates of ballistic combined femoral neck and shaft fracture within the known range for blunt mechanisms but with a likely different mechanism causing the associated neck fracture. The ability to properly diagnose combined femoral shaft and neck fractures is a challenge, with Tornetta et. al showing high rates of missed femoral neck involvement on injury presentation [ 3 ]. Our institution attempted to follow the standard protocol of pre-operative radiographs of the ipsilateral hip, a CT scan including the femoral neck, and dedicated intra-operative and post-operative radiographs. Research by O’Toole et al. examined the sensitivity and specificity of detecting femoral neck fractures in a blunt femoral shaft fracture cohort using AP pelvis and AP femur radiographs as well as axial-view CT scans of the pelvis [ 6 ]. While AP radiographs had a sensitivity of only 50% in diagnosing femoral neck fractures, their results showed that CT imaging was only marginally better at detection, with a still undesirable sensitivity of 64% [ 6 ]. In our study, CT imaging revealed both instances of femoral neck involvement and plain radiographs alone were insufficient to make the diagnosis. Though we had no cases of concurrent femoral neck fractures discovered intra- or post-operatively, the work by both Tornetta and O’Toole highlights the importance of obtaining complete imaging for each patient. Our study’s limitations are derived from the small sample size and retrospective nature. With only one other study reporting on the existence of ballistic femoral neck/shaft fractures, there is insufficient data to conduct a power analysis and evaluate our sample size for an injury of low incidence. Current research demonstrates that magnetic resonance imaging (MRI) is the best method of detecting femoral neck fractures not visible on XR or CT imaging in the setting of a femoral shaft fracture [ 13 ]. MRI imaging was not performed on any patients in this series, raising the possibility of missed femoral neck fractures. As more than half of the patients had fixation across the femoral neck with the use of reconstruction intramedullary nails, it is possible that these injuries also did not present post-operatively. Ultimately, our study adds value to the sparse literature on combined ballistic femoral neck and shaft injuries, highlighting that surgeons need to maintain vigilance for these difficult-to-diagnose injuries. 5. Conclusion Ballistic fractures of the femoral shaft carry a low risk of ipsilateral femoral neck involvement. Understanding the incidence and injury patterns associated with femoral neck involvement is a crucial component in diagnosing and treating these injuries. Declarations The authors have no relevant financial or non-financial interests to disclose. The authors did not receive support from any organization for the submitted work. All patient data was collected in a HIPPA-compliant method under an approved institutional IRB protocol All data supporting the findings of this study are available within the paper and its Supplementary Information. Author Contribution All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Clayton Welsh, Matthew Todd, and Michael McGraw. The first draft of the manuscript was written by Clayton Welsh and Michael McGraw and all authors commented on previous versions of the manuscript. References Tornetta P, Ollivere BJ, McKee MD., Ostrum RF, de Ridder VA. Rockwood and Green's Fractures in Adults. 9th ed. Philadelphia: Wolters Kluwer; 2024. Alho A. Concurrent ipsilateral fractures of the hip and femoral shaft: a meta-analysis of 659 cases. Acta Orthop Scand. 1996;67(1):19-28. doi:10.3109/17453679608995603 Tornetta P 3rd, Kain MS, 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):39-43. doi:10.2106/JBJS.F.00297 Watson JT, Moed BR. Ipsilateral femoral neck and shaft fractures: complications and their treatment. Clin Orthop Relat Res. 2002;(399):78-86. doi:10.1097/00003086-200206000-00011 Bennett FS, Zinar DM, Kilgus DJ. Ipsilateral hip and femoral shaft fractures. Clin Orthop Relat Res. 1993;(296):168-177. OʼToole RV, Dancy L, Dietz AR, et al. Diagnosis of femoral neck fracture associated with femoral shaft fracture: blinded comparison of computed tomography and plain radiography. J Orthop Trauma. 2013;27(6):325-330. doi:10.1097/BOT.0b013e318271b6c8 Boulton CL, Pollak AN. Special topic: Ipsilateral femoral neck and shaft fractures--does evidence give us the answer?. Injury. 2015;46(3):478-483. doi:10.1016/j.injury.2014.11.021 Riemer BL, Butterfield SL, Ray RL, Daffner RH. Clandestine femoral neck fractures with ipsilateral diaphyseal fractures. J Orthop Trauma. 1993;7(5):443-449. doi:10.1097/00005131-199310000-00007 Dougherty PJ, Sherman D, Dau N, Bir C. Ballistic fractures: indirect fracture to bone. J Trauma. 2011;71(5):1381-1384. doi:10.1097/TA.0b013e3182117ed9 Kieser DC, Carr DJ, Leclair SC, et al. Gunshot induced indirect femoral fracture: mechanism of injury and fracture morphology. J R Army Med Corps. 2013;159(4):294-299. doi:10.1136/jramc-2013-000075 Veenstra A, Kerkhoff W, Oostra RJ, Galtés I. Gunshot trauma in human long bones: towards practical diagnostic guidance for forensic anthropologists. Forensic Sci Med Pathol. 2022;18(3):359-367. doi:10.1007/s12024-022-00479-0 Baker HP, Dahm J, Schultz K, Portney D, Dillman D, Strelzow J. A comparison of the incidence of concomitant ipsilateral femoral neck fractures in ballistic versus blunt femur fractures. Eur J Orthop Surg Traumatol. 2023;33(4):843-850. doi:10.1007/s00590-022-03219-w Rogers NB, Achor TS., Kumaravel M, Gary, JL., Munz JW, Choo AM, Routt ML Jr, 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), 2390–2394. Doi:10.1016/j.injury.2021.05.009 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-9335057","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":626528545,"identity":"c778beb9-3bc2-4c9f-9489-b6725e8867b4","order_by":0,"name":"Clayton Welsh","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABAklEQVRIiWNgGAWjYDACdgSDjSHhhw2Qxdh4AK8WZiA+AGGwMTzsSQNpaSBeC+MDtsNgQbxa+JuZn0l/qLiT2M/M/uxBAs95u7Xth4G21NhE49IicZjNTOLAmWeJM5t5zA0SLG4nbzuTCNRyLC23AYcWA2YGM4mDbYdzNxzmYZNI4LmdbHYAqIWx4TAeLezfwFr2H2Z/JpHAdi7Z7PxDQlp4oLaArEtgO2BndoOALRKHeYotzpw5XD/jMFBvYk9ygtkNoC0JePzC396+8UZFxWFjIOOZ5I8fdvZm59MfPvhQY4NTCxCwSCDzEsEqE3ArBwHmD8g8e/yKR8EoGAWjYCQCAK9JZGRbZnnjAAAAAElFTkSuQmCC","orcid":"","institution":"Northwestern University","correspondingAuthor":true,"prefix":"","firstName":"Clayton","middleName":"","lastName":"Welsh","suffix":""},{"id":626528547,"identity":"fa15b01b-cf12-4b00-a8ac-d8d175688a61","order_by":1,"name":"Michael McGraw","email":"","orcid":"","institution":"Franciscan Health","correspondingAuthor":false,"prefix":"","firstName":"Michael","middleName":"","lastName":"McGraw","suffix":""},{"id":626528555,"identity":"2943c1b8-e9c7-411c-a08d-99b8082cde9e","order_by":2,"name":"Matthew Todd","email":"","orcid":"","institution":"Franciscan Health","correspondingAuthor":false,"prefix":"","firstName":"Matthew","middleName":"","lastName":"Todd","suffix":""},{"id":626528558,"identity":"a340743f-8bfa-46d7-8608-1a20ddbbc474","order_by":3,"name":"Colin Cantrell","email":"","orcid":"","institution":"Northwestern University","correspondingAuthor":false,"prefix":"","firstName":"Colin","middleName":"","lastName":"Cantrell","suffix":""},{"id":626528562,"identity":"614d78ac-81e0-4552-8eed-a6c68ca3d164","order_by":4,"name":"Bennet Butler","email":"","orcid":"","institution":"John H. Stroger, Jr. Hospital of Cook County","correspondingAuthor":false,"prefix":"","firstName":"Bennet","middleName":"","lastName":"Butler","suffix":""}],"badges":[],"createdAt":"2026-04-06 14:53:12","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9335057/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9335057/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":107614250,"identity":"9bf6839e-4e5d-4fb2-b929-c217d1cdc2ca","added_by":"auto","created_at":"2026-04-23 09:07:34","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":197011,"visible":true,"origin":"","legend":"\u003cp\u003eExample demonstrating the measured distance on XR imaging from the medial-most point of the lesser trochanter to the most proximal extent of primary fracture comminution\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-9335057/v1/068ae00c1420d1b6e57ca57f.png"},{"id":107614248,"identity":"1b7c1f13-909f-413e-843b-259b7e5c2034","added_by":"auto","created_at":"2026-04-23 09:07:34","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":196575,"visible":true,"origin":"","legend":"\u003cp\u003eInjury XR and CT scan for the first instance of femoral neck involvement\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-9335057/v1/c35482870093e0a5aed21574.png"},{"id":107614249,"identity":"7b6b7453-8c3a-41a0-b045-e5a8afeb5b8f","added_by":"auto","created_at":"2026-04-23 09:07:34","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":280639,"visible":true,"origin":"","legend":"\u003cp\u003eInjury XR and CT scan for the second instance of femoral neck involvement\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-9335057/v1/5ab9ff14951c65a56c07618c.png"},{"id":108006105,"identity":"e152164a-b1ea-4f6e-b295-09ca440c1664","added_by":"auto","created_at":"2026-04-28 12:53:20","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1003014,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9335057/v1/522003e6-27ca-4c56-be55-384b54fba385.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Ipsilateral Femoral Neck Fracture Rates Following Ballistic Fractures of the Femoral Shaft","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eFemoral shaft fractures often occur concurrently with injuries to both the axial and appendicular skeleton, and ipsilateral fractures of the femoral neck occur in 1% to 9% of high-energy femoral shaft fractures [\u003cspan additionalcitationids=\"CR2 CR3 CR4\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Diagnosing a femoral neck fracture in the setting of a femoral shaft fracture can be difficult, with 20\u0026ndash;50% of femoral neck fractures missed on injury presentation [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. To reduce the rate of missed injuries, current imaging protocols involve dedicated pre-operative, intra-operative, and post-operative radiographs of the ipsilateral hip as well as a pre-operative computed tomography (CT) scan with two-millimeter slices through the femoral neck [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Despite increased awareness, pre-operative XR and CT imaging still has poor sensitivity for diagnosing ipsilateral femoral neck fractures pattern [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Missed femoral neck fractures can have devastating long-term impacts, including nonunion, malunion, avascular necrosis necessitating further operations [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe initial research to uncover the rates of ipsilateral femoral shaft/neck fractures examined injuries of a blunt mechanism, most frequently vehicular crashes [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. In a blunt injury, the combined femoral shaft and neck fracture is postulated to result from a longitudinal force transmitted up the femoral shaft and across a flexed and abducted hip [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. The mechanism of a ballistic injury differs significantly, with fractures resulting from either the direct impact of a bullet striking bone or through indirect forces generated by the bullet\u0026rsquo;s energy. As a bullet travels through soft tissue, it is preceded by a shockwave that creates a temporary cavity of up to 12.5 times the diameter of the bullet [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. The force of generated by the temporary cavity is enough to fracture bones, even without a direct impact from the bullet [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Whereas fractures from the direct impact of the bullet typically result in severe comminution, indirect fractures are often minimally displaced and can be more difficult to detect on plain radiographs [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Through either direct extension of comminution or the creation of a wide temporary cavity, ballistic fractures of the femoral shaft may have a similar association with femoral neck fractures as seen in blunt mechanisms.\u003c/p\u003e \u003cp\u003eThis study will investigate the characteristics of ballistic femoral shaft fractures and the incidence of ipsilateral femoral neck fractures. We will further investigate the efficacy of XR, CT, and intraoperative fluoroscopy in detecting femoral neck involvement. We hypothesize that there will be a similar rate of femoral neck involvement in ballistic and blunt mechanisms.\u003c/p\u003e"},{"header":"2. Methods","content":"\u003cp\u003eWe performed an IRB-approved retrospective review of ballistic diaphyseal femur fractures at a single level one trauma center between 2015 and 2023. Patients over the age of 18 with operatively treated femur fractures of a known ballistic mechanism were included. Pediatric patients, patients with non-operative ballistic fractures, and fractures with a primary zone of comminution in the intertrochanteric, femoral neck, supracondylar, or distal femur region were excluded. Patients were sequentially identified through consult lists, surgical schedules, and a review of the electronic medical record.\u003c/p\u003e \u003cp\u003eAll patients were admitted to the hospital as trauma activations and underwent surgical stabilization of their femur fractures with either intramedullary implants or plate and screw constructs. We recorded demographic information including age at presentation, time to surgery, and method of surgical fixation. Injury XRs and CT scans were used to classify patients according to the AO/OTA classification system for diaphyseal femur fractures. To better stratify which patients would be most at risk of femoral neck involvement, we measured the distance in millimeters (mm) from the most medial point of the lesser trochanter to the most proximal extent of direct fracture comminution on AP radiographs. (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). When the primary femoral shaft fracture had direct extension above the lesser trochanter, negative values were used. In patients with available CT imaging, we performed a similar process using the most medial point of the lesser trochanter to the most proximal extent of fracture comminution (Fig.\u0026nbsp;2).\u003c/p\u003e \u003cp\u003eInjury XRs and CT, operating room fluoroscopy, operative reports, and post-operative XRs were reviewed to note the presence of an ipsilateral femoral neck fracture. Radiographic analysis of each available injury XR and CT was performed by two reviewers to determine the injury classification and proximal extension of the femoral shaft fracture.\u003c/p\u003e"},{"header":"3. Results","content":"\u003cp\u003eThe study included 77 patients who sustained ballistic fractures of the femoral diaphysis. 74 of the 77 patients (95%) were male, with an average age of 28 years old (range 18\u0026ndash;57). AO/OTA 32C was the most common fracture pattern, with 72 of 77 (94%) femoral shaft fractures being significantly comminuted (Table\u0026nbsp;1). CT imaging of the femoral neck was available for 66 of the 77 patients (86%).\u003c/p\u003e\n\u003cp\u003eTable 1: AO/OTA injury classification results\u003c/p\u003e\n\u003cp\u003e\u003cimg src=\"https://myfiles.space/user_files/58895_8739fc6c57c1c19a/58895_custom_files/img1776864901.png\" width=\"643\" height=\"175\"\u003e\u003c/p\u003e\n\u003cp\u003eTwo patients (2.6%) had femoral shaft fractures with direct extension into the femoral neck (Figs.\u0026nbsp;2 and 3). In each instance, the femoral neck fracture was not visible on injury XR but identified on CT imaging before operative intervention. CT imaging for both instances showed an uninterrupted fracture line from the primary zone of comminution into the femoral neck. No femoral neck fractures occurred independent of the site of primary femoral shaft comminution. No femoral neck fractures were uncovered by intra-operative and post-operative radiographs that were not seen on CT imaging prior to the OR. The average distance from the lesser trochanter to the most proximal extent of the primary site of fracture comminution was 63 millimeters (range\u0026thinsp;\u0026minus;\u0026thinsp;34 to 236). The two fractures of the femoral neck had visible proximal extension of their shaft fractures 21 and 33 millimeters above the lesser trochanter respectively.\u003c/p\u003e"},{"header":"4. Discussion","content":"\u003cp\u003eOur study addresses the rate of femoral neck involvement following ballistic diaphyseal femur fractures. Our results indicate a low rate of femoral neck involvement, with just 2.6% of patients being affected. Our incidence fits within the established 1\u0026ndash;9% rate of combined femoral shaft and neck fractures drawn from blunt mechanisms of injury [\u003cspan additionalcitationids=\"CR2 CR3 CR4\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Through both direct and indirect mechanisms, ballistic fractures behave differently from blunt fractures with wide temporary zones of injury [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. As opposed to axial force transmission along the femoral shaft in blunt mechanisms, our data showed the ballistic mechanism of a combined shaft and neck fracture is due to direct extension of the fracture into the neck. In an additional study on combined ballistic femoral neck and shaft fractures, Baker et. al examined ballistic femur fractures in 68 patients and compared them to a blunt cohort [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. In this series, femoral neck fractures were seen in 5.8% of patients with no difference in femoral neck fracture rates between blunt and ballistic injury mechanisms. In three of the four instances reported by Baker et. al, femoral neck fractures were caused by a direct propagation of fracture lines across the intertrochanteric region with only one instance of a non-contiguous femoral neck fracture identified through CT imaging [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Overall, our study demonstrates rates of ballistic combined femoral neck and shaft fracture within the known range for blunt mechanisms but with a likely different mechanism causing the associated neck fracture.\u003c/p\u003e \u003cp\u003eThe ability to properly diagnose combined femoral shaft and neck fractures is a challenge, with Tornetta et. al showing high rates of missed femoral neck involvement on injury presentation [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Our institution attempted to follow the standard protocol of pre-operative radiographs of the ipsilateral hip, a CT scan including the femoral neck, and dedicated intra-operative and post-operative radiographs. Research by O\u0026rsquo;Toole et al. examined the sensitivity and specificity of detecting femoral neck fractures in a blunt femoral shaft fracture cohort using AP pelvis and AP femur radiographs as well as axial-view CT scans of the pelvis [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. While AP radiographs had a sensitivity of only 50% in diagnosing femoral neck fractures, their results showed that CT imaging was only marginally better at detection, with a still undesirable sensitivity of 64% [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. In our study, CT imaging revealed both instances of femoral neck involvement and plain radiographs alone were insufficient to make the diagnosis. Though we had no cases of concurrent femoral neck fractures discovered intra- or post-operatively, the work by both Tornetta and O\u0026rsquo;Toole highlights the importance of obtaining complete imaging for each patient.\u003c/p\u003e \u003cp\u003eOur study\u0026rsquo;s limitations are derived from the small sample size and retrospective nature. With only one other study reporting on the existence of ballistic femoral neck/shaft fractures, there is insufficient data to conduct a power analysis and evaluate our sample size for an injury of low incidence. Current research demonstrates that magnetic resonance imaging (MRI) is the best method of detecting femoral neck fractures not visible on XR or CT imaging in the setting of a femoral shaft fracture [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. MRI imaging was not performed on any patients in this series, raising the possibility of missed femoral neck fractures. As more than half of the patients had fixation across the femoral neck with the use of reconstruction intramedullary nails, it is possible that these injuries also did not present post-operatively. Ultimately, our study adds value to the sparse literature on combined ballistic femoral neck and shaft injuries, highlighting that surgeons need to maintain vigilance for these difficult-to-diagnose injuries.\u003c/p\u003e"},{"header":"5. Conclusion","content":"\u003cp\u003eBallistic fractures of the femoral shaft carry a low risk of ipsilateral femoral neck involvement. Understanding the incidence and injury patterns associated with femoral neck involvement is a crucial component in diagnosing and treating these injuries.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eThe authors have no relevant financial or non-financial interests to disclose.\u003c/p\u003e\n\u003cp\u003eThe authors did not receive support from any organization for the submitted work.\u003c/p\u003e\n\u003cp\u003eAll patient data was collected in a HIPPA-compliant method under an approved institutional IRB protocol\u003c/p\u003e\n\u003cp\u003eAll data supporting the findings of this study are available within the paper and its Supplementary Information.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eAll authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Clayton Welsh, Matthew Todd, and Michael McGraw. The first draft of the manuscript was written by Clayton Welsh and Michael McGraw and all authors commented on previous versions of the manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eTornetta P, Ollivere BJ, McKee MD., Ostrum RF, de Ridder VA. Rockwood and Green\u0026apos;s Fractures in Adults. 9th ed. Philadelphia: Wolters Kluwer; 2024.\u003c/li\u003e\n \u003cli\u003eAlho A. Concurrent ipsilateral fractures of the hip and femoral shaft: a meta-analysis of 659 cases. Acta Orthop Scand. 1996;67(1):19-28. doi:10.3109/17453679608995603\u003c/li\u003e\n \u003cli\u003eTornetta P 3rd, Kain MS, 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):39-43. doi:10.2106/JBJS.F.00297\u003c/li\u003e\n \u003cli\u003eWatson JT, Moed BR. Ipsilateral femoral neck and shaft fractures: complications and their treatment. Clin Orthop Relat Res. 2002;(399):78-86. doi:10.1097/00003086-200206000-00011\u003c/li\u003e\n \u003cli\u003eBennett FS, Zinar DM, Kilgus DJ. Ipsilateral hip and femoral shaft fractures. Clin Orthop Relat Res. 1993;(296):168-177.\u003c/li\u003e\n \u003cli\u003eOʼToole RV, Dancy L, Dietz AR, et al. Diagnosis of femoral neck fracture associated with femoral shaft fracture: blinded comparison of computed tomography and plain radiography. J Orthop Trauma. 2013;27(6):325-330. doi:10.1097/BOT.0b013e318271b6c8\u003c/li\u003e\n \u003cli\u003eBoulton CL, Pollak AN. Special topic: Ipsilateral femoral neck and shaft fractures--does evidence give us the answer?. Injury. 2015;46(3):478-483. doi:10.1016/j.injury.2014.11.021\u003c/li\u003e\n \u003cli\u003eRiemer BL, Butterfield SL, Ray RL, Daffner RH. Clandestine femoral neck fractures with ipsilateral diaphyseal fractures. J Orthop Trauma. 1993;7(5):443-449. doi:10.1097/00005131-199310000-00007\u003c/li\u003e\n \u003cli\u003eDougherty PJ, Sherman D, Dau N, Bir C. Ballistic fractures: indirect fracture to bone. J Trauma. 2011;71(5):1381-1384. doi:10.1097/TA.0b013e3182117ed9\u003c/li\u003e\n \u003cli\u003eKieser DC, Carr DJ, Leclair SC, et al. Gunshot induced indirect femoral fracture: mechanism of injury and fracture morphology. J R Army Med Corps. 2013;159(4):294-299. doi:10.1136/jramc-2013-000075\u003c/li\u003e\n \u003cli\u003eVeenstra A, Kerkhoff W, Oostra RJ, Galt\u0026eacute;s I. Gunshot trauma in human long bones: towards practical diagnostic guidance for forensic anthropologists. Forensic Sci Med Pathol. 2022;18(3):359-367. doi:10.1007/s12024-022-00479-0\u003c/li\u003e\n \u003cli\u003eBaker HP, Dahm J, Schultz K, Portney D, Dillman D, Strelzow J. A comparison of the incidence of concomitant ipsilateral femoral neck fractures in ballistic versus blunt femur fractures. Eur J Orthop Surg Traumatol. 2023;33(4):843-850. doi:10.1007/s00590-022-03219-w\u003c/li\u003e\n \u003cli\u003eRogers NB, Achor TS., Kumaravel M, Gary, JL., Munz JW, Choo AM, Routt ML Jr, 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;2394. Doi:10.1016/j.injury.2021.05.009\u003c/li\u003e\n\u003c/ol\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":"Orthopaedic Trauma, Fracture, Femoral Shaft, Femoral Neck","lastPublishedDoi":"10.21203/rs.3.rs-9335057/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9335057/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eIntroduction:\u003c/strong\u003e Prior literature demonstrates that in patients with blunt femoral shaft fractures, ipsilateral femoral neck fractures occur at a rate of 1-9% and can be challenging to diagnose. Ballistic fractures of the femoral shaft remain an area of ongoing research, with little evidence examining whether these fractures also carry an increased risk of ipsilateral femoral neck fracture. The purpose of this study is to evaluate the incidence of concurrent ipsilateral femoral neck and femoral shaft fractures after ballistic injuries.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods: \u003c/strong\u003eWe performed a retrospective review of ballistic diaphyseal femur fractures treated with operative fixation in adult. Operative reports, X-ray (XR), and computed tomography (CT) images were utilized to assess for ipsilateral femoral neck fractures diagnosed at the time of injury, intra-operatively, or post-operatively.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults: \u003c/strong\u003eThe study included 77 patients who sustained ballistic fractures of the femoral diaphysis. 94% of fractures were classified as AO/OTA 32C. Two patients (2.6%) had femoral shaft fractures with direct extension into the femoral neck identified on CT imaging. No femoral neck fractures occurred independent of the site of primary femoral shaft comminution.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion: \u003c/strong\u003eBallistic fractures of the femoral shaft carry a low risk of ipsilateral femoral neck involvement. Understanding the incidence of femoral neck involvement is a crucial component in diagnosing and treating these injuries.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eLevel of Evidence: \u003c/strong\u003eLevel 4\u003c/p\u003e","manuscriptTitle":"Ipsilateral Femoral Neck Fracture Rates Following Ballistic Fractures of the Femoral Shaft","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-23 09:07:30","doi":"10.21203/rs.3.rs-9335057/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":"f07e4e4c-81ef-43cf-9c57-31e92118be18","owner":[],"postedDate":"April 23rd, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-04-25T23:23:25+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-23 09:07:30","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9335057","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9335057","identity":"rs-9335057","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}