Risk Factors and Predictors of Contralateral Hip Fracture After Surgical Treatment in Elderly Patients

Risk Factors and Predictors of Contralateral Hip Fracture After Surgical Treatment in Elderly Patients | 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 Article Risk Factors and Predictors of Contralateral Hip Fracture After Surgical Treatment in Elderly Patients Huan Yang, Yusong Yuan, Ruidong Ge, Lei Shi, Fangda Si, Ying Chen This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6144656/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background: Hip fractures are common in elderly patients, with some experiencing contralateral fractures. Even so, information on predictors of hip fractures in elderly adults is lacking. In this study, we investigated risk factors for contralateral hip fractures after surgical treatment of primary fractures. Methods: This was a prospective cohort study of 115 patients aged ≥65 years with low-energy hip fractures. The clinical parameters evaluated included age, sex, bone mineral density (BMD), T score, and hip flexor strength deficit. Patients were stratified into two groups: those with (n=12) and those without contralateral fractures (n=103). Results: Contralateral fractures occurred in 10.4% of the patients. Logistic regression revealed thatage (OR=1.08), reduced BMD (OR=0.33), lower T score (OR=1.45), and hip flexor imbalance (OR=2.2) weresignificant predictors. Conclusion: A multimodal approach that integratesanti-osteoporosis therapy and targeted rehabilitation may reduce contralateral fracture risk in elderly patients. Health sciences/Medical research Health sciences/Risk factors Hip fracture osteoporosis bone mineral density muscle imbalance rehabilitation geriatric trauma secondary prevention Figures Figure 1 Introduction The increasing prevalence of osteoporotic hip fractures in aging populations has drawn significant attention to contralateral hip fractures, which occur in 6.8–16.0% of patients with osteoporotic hip fractures [1,16,17] . While previous research has focused predominantly on demographic and skeletal factors [1,3,18] , emerging evidence underscores the importance of biomechanical contributors, particularly postural instability and muscle weakness [2] . The aim of this study was to combine biomechanical (hip flexor strength) and skeletal (BMD) parameters to identify multifactorial predictors of contralateral fractures. To our knowledge, this is the first prospective cohort study to integrate both biomechanical (hip flexor strength) and skeletal (BMD) parameters in the prediction of contralateral hip fractures. Study Objectives and Design The investigation focused on systematically evaluating biomechanical, biochemical, and functional parameters, including 1) bone quality metrics (BMD and T scores via DXA); 2) neuromuscular functional capacity (hip flexor strength quantified through isokinetic dynamometry); 3) clinical outcomes (Harris Hip Scores); and 4) demographic/operative characteristics. A standardized data collection protocol was implemented across perioperative hospitalization and postdischarge follow-up (6-month intervals) to ensure longitudinal validity. Materials and methods Consecutive patients who underwent surgical management for low-energy hip fractures at our Level I Trauma Center (January 2022-December 2023) and met the following criteria were included: 1. Age ≥ 65 years with low-energy trauma (fall from standing height); 2. Radiographically confirmed intertrochanteric (AO/OTA 31-A; n = 55) or femoral neck fractures (Garden II-IV; n = 60); and 3. Independent ambulation status prior to the fracture. Furthermore, patients were excluded if they met any of the following criteria: nonsurgical candidate, pathological fracture, neurological/musculoskeletal comorbidity, or visual impairment (best-corrected acuity < 20/40). Postoperative Protocol: All patients received standardized anti-osteoporosis therapy and procedure-specific rehabilitation. In particular, in cases of PFNA fixation (n = 72), protected weight-bearing was implemented for ≥ 6 weeks, and in cases of arthroplasty (n = 43), immediate full weight-bearing post quadriceps- strength assessment (MMT grade IV) was implemented. Ethical Compliance Statement This study was approved by the Ethics Committee of China-Japan Friendship Hospital (Approval No. 2023-KY-145), and written informed consent was obtained from all participants. All procedures involving human subjects were conducted in strict accordance with the ethical standards of the Declaration of Helsinki (2013 revision), the International Council for Harmonisation (ICH) Guidelines for Good Clinical Practice (GCP), and institutional review board (IRB) policies. Patient confidentiality and data anonymity were rigorously maintained throughout the study. Outcome assessment Operative Protocol Surgical procedures followed standard protocols for intertrochanteric fractures (PFNA fixation) and femoral neck fractures (hemiarthroplasty/THA). Postoperation Protocol All enrolled patients were routinely administered analgesics, anticoagulants and anti-osteoporosis medications according to standardized protocols. On postoperative day 2, targeted rehabilitation exercises focusing on quadriceps femoris activation, with particular emphasis on the vastus medialis oblique (VMO), were initiated. Patients were permitted to commence partial weight-bearing ambulation with full assistive support only after achieving grade IV muscle strength in the quadriceps femoris, as assessed by manual muscle testing (MMT). Follow-up At the 6-month postoperative follow-up, comprehensive functional assessments were performed. Hip abductor function was evaluated using the standardized Trendelenburg test 26 , with positive findings (inability to maintain pelvic alignment during a single-leg stance), resulting in study exclusion. Hip flexor strength, represented by peak torque (PT), was measured using the BIODEX SYSTEM 4 PRO (Biodex Medical Systems, Inc., Shirley, NY) under the supervision of licensed physical therapists. The testing protocol involved a unilateral stance with rapid contralateral leg elevation, measuring peak torque (ft-lb) and automatically calculating torque deficit percentages. Deficit severity was categorized as follows: (1) 1–10%, within normal limits; (2) 11–20%, indicating the need for rehabilitation; and (3) > 20%, representing significant functional impairment. All measurements were recorded immediately postassessment to ensure data integrity and reliability. Study Groups The study population was stratified into two comparative cohorts on the basis of fracture characteristics: Group A (n = 12) consisted of patients presenting with contralateral hip fractures, and Group B (n = 103) comprised patients without contralateral involvement. A comprehensive comparative analysis was conducted between these cohorts. The variables in this analysis comprised multiple demographic and clinical parameters, including but not limited to age distribution, sex ratio, fracture classification according to the AO/OTA system, bone mineral density (BMD) in the hip region, T scores derived from dual-energy X-ray absorptiometry (DEXA) scans, length of hospital stay, Harris Hip Score (HHS) for functional assessment, and isokinetic measurements of hip flexor peak torque with corresponding deficit calculations. Statistical Analysis The sample size of 115 was determined on the basis of a power analysis (α = 0.05, β = 0.20) to detect a 15% difference between groups. All the statistical analyses were performed using PASW Statistics 21.0 software (IBM Corp., Armonk, NY, USA). Intergroup comparisons between Group A and Group B were conducted for multiple variables. Continuous variables, including age, time interval from injury to surgical intervention, length of hospital stay, bone mineral density (BMD), T score, Harris hip score (HHS), and isokinetic measurements of hip flexor peak torque (with associated deficit values), were analyzed using independent samples t tests following the confirmation of a normal distribution by means of Shapiro–Wilk tests. Categorical variables, such as sex distribution and fracture classification, were evaluated using Pearson's chi-square (χ2) test or Fisher's exact test, as appropriate. Missing data, which accounted for less than 5% of the total dataset, were excluded from the analysis under the assumption of being missing completely at random (MCAR). Variables demonstrating statistically significant differences (p < 0.05) in the univariate analysis were subsequently incorporated into multivariate logistic regression models to identify independent predictors. A two-tailed p value of < 0.05 was considered statistically significant for all analyses. Results Consecutive patients (N = 115) enrolled while 3 patients were excluded due to their request to withdraw consent. Contralateral fractures occurred in 10.4% of the patients (12/115) at a mean latency of 14.3 ± 3.8 months. Compared with the patients in Group B, those in Group A (contralateral fractures) were significantly older (84.3 vs. 79.1 years, p = 0.015), had a lower BMD (0.68 vs. 0.77 g/cm², p = 0.021), and had higher proportion of cases of hip flexor deficit (22.5% vs. 14.6%, p = 0.032) (Table 1 ). Multivariate analysis revealed that age, male sex, T score, BMD, and hip flexor deficit were independent risk factors (Table 3 ). Postoperative Outcomes and Fracture Epidemiology The mean hospitalization duration was 8.7 ± 3.2 days (range: 3–22) in the prospective cohort, and the injury-to-surgery interval was 1.8 ± 0.9 days (range: 1–3), with no intergroup differences ( p > 0.05). Systematic follow-up over 6–20 months revealed a contralateral fracture incidence of 10.4% (12/115), indicating a balanced sex ratio, comprising 6 males and 6 females, representing an equal proportion (50%) in Group A. Fracture patterns were comparable between intertrochanteric (10.9%, 6/55) and femoral neck fractures (10.0%, 6/60). Contralateral hip fractures occurred at a mean latency of 14.3 ± 3.8 months postoperatively (range: 9–20). Surgical and Rehabilitation Protocols All patients received standardized anti-osteoporosis therapy (calcium/alfacalcidol) and procedure-specific rehabilitation: PFNA fixation (n = 72): Protected weight-bearing for ≥ 6 weeks with progressive quadriceps strengthening. Arthroplasty (n = 43): Immediate full weight-bearing upon achieving MMT grade IV quadriceps strength. Postoperative hip mobility was restricted to -10°–90° during the first month, supplemented by supervised isometric exercises initiated within 24 hours postoperatively. Comparative Analysis of Risk Factors Univariate analysis revealed significant disparities between the contralateral fracture (Group A, n = 12) and control (Group B, n = 103) cohorts (Table 1 ). Table 1 Univariate analysis of risk factors Parameter Group A Group B Statistical Significance Age (years) 84.3 ± 5.1 79.1 ± 6.8 t =-2.16 p =0.03 BMD (g/cm²) 0.68 ± 0.11 0.77 ± 0.09 t = 2.15 p =0.03 T score -3.1 ± 0.8 -2.0 ± 0.7 t = 4.94 p <0.001 Peak torque (uninvolved) 58.7 ± 7.9 63.2 ± 8.1 t = 2.15 p =0.03 Hip flexor deficit (%) 22.5 ± 5.3 14.6 ± 4.1 t = -2.01 p =0.047 BMD: Bone mineral density; PFNA: Proximal femoral nail antirotation; MMT: Manual muscle testing No significant differences were observed between Group A and Group B in terms of sex, length of hospital stay, fracture type, Harris score, or involved hip flexor peak torque (Table 2 ). Table 2 Comparison of Clinical Characteristics between Group A and Group B Variable Group A (n = 12) Group B (n = 103) Statistical Value p value Sex (Male/Female) 4 (33.3%)/8(66.7%) 29 (28.2%)/74(71.8%) χ²=3.45 0.06 Length of Hospital Stay (days) 9.8 ± 4.2 8.5 ± 3.1 t =-0.78 0.44 Fracture Type - Intertrochanteric Fracture 5 (41.7%) 50 (48.5%) χ²=6.356 0.70 - Femoral Neck Fracture 7 (58.3%) 53 (51.5%) Harris Score 81.0 ± 10.88 79.95 ± 10.73 t =-0.54 0.60 Peak Torque (involved) 55.1 ± 7.2 52.8 ± 6.7 t =-1.23 0.22 The logistic regression analysis revealed that age, male sex, lower T scores, reduced BMD, and greater hip flexor deficit were significant risk factors for contralateral hip fractures. These findings highlight the importance of addressing both skeletal and biomechanical factors in the prevention and management of contralateral hip fractures in elderly patients (Table 3 ). Table 3 Multivariate Logistic Regression Analysis of Independent Risk Factors for Contralateral Hip Fractures Variable β SE p value OR CI Age 0.072 0.29 0.012 1.08 [1.02,1.15] Sex 0.210 0.40 0.603 1.23 [0.56, 2.71] Hospital Stays -0.015 0.038 0.692 0.98 [0.91,1.06] Fracture type 0.102 0.189 0.589 1.11 [0.76,1.61] BMD -1.139 0.518 0.028 0.32 [0.11,0.89] T score 0.372 0.140 0.008 1.45 [1.10,1.92] Harris score -0.008 0.014 0.567 0.99 [0.97,1.02] PT (Involved) -0.015 0.02 0.454 0.98 [0.94,1.03] PT (Uninvolved) -0.021 0.018 0.244 0.99 [0.94,1.02] PT deficit (%) 0.788 0.286 0.006 2.2 [1.25,3.86] BMD: Bone mineral density; PT: Peak torque; PT: deficit: Peak torque deficit; Kaplan‒Meier analysis revealed a cumulative contralateral fracture incidence of 10.4% at 20 months (Fig. 1 ). The Kaplan-Meier curve illustrates the cumulative incidence of contralateral hip fractures over a 20-month follow-up period in elderly patients following surgical treatment of primary hip fractures. The x-axis represents time in months, and the y-axis shows the cumulative survival probability (i.e., the proportion of patients without contralateral fractures). The curve demonstrates a gradual decline in survival probability, with a cumulative incidence of 10.4% at 20 months. Censored data points (indicated by "+" symbols) represent patients who experienced a contralateral hip fracture. This analysis highlights the temporal pattern of contralateral fracture risk, emphasizing the need for extended monitoring and secondary prevention strategies beyond the first-year post-surgery. Factors Associated with Contralateral Hip Fractures Bone mineral density (BMD) measurements revealed a mean of 0.68 ± 0.11 in Group A and 0.77 ± 0.09 in Group B ( t = 2.15, p = 0.03), whereas T scores of -3.1 ± 0.8 in Group A and − 2.0 ± 0.7 in Group B indicated more severe osteoporosis in patients with contralateral fractures ( t = 4.94, p < 0.001). The musculoskeletal assessment revealed that the percent deficit in hip flexor strength was significantly greater in Group A (22.5 ± 5.3) than in Group B (14.6 ± 4.1); t = -2.01, p = 0.047), suggesting greater bilateral muscle imbalance in patients with contralateral fractures. Discussion The synergistic effect of advanced age and reduced BMD underscores the critical role of osteoporosis management in contralateral fracture prevention [2,15,17] , as evidenced by our findings (Group A: BMD 0.68 vs. Group B: 0.77 g/cm², p = 0.03). A lower T score (-3.1 vs. -2.0, p < 0.001) aligns with prior evidence that age-related bone loss exacerbates fracture risk [20] . The mean latency period of 14.3 months postoperatively highlights a critical window for secondary prevention, potentially linked to delayed bone remodeling and altered weight-bearing mechanics [18,19] . Extended follow-up protocols beyond 12 months may improve monitoring efficacy. Notably, hip flexor strength imbalance (OR = 2.2) emerged as a stronger biomechanical predictor, suggesting targeted rehabilitation to mitigate gait instability and fall risk [20] . The findings of this study provide critical insights into the multifactorial nature of contralateral hip fractures in elderly patients, highlighting several key areas for clinical consideration and future research. Age/BMD interaction The significant correlation between advanced age and reduced bone mineral density (BMD) underscores the synergistic effect of these factors in increasing contralateral hip fracture risk 2 , 15 , 17 , 18 , 19 , 20 . Our data show that in patients with contralateral fractures, compared with those of the controls, the BMD values of the patients are significantly lower (0.68 ± 0.11 g/cm²), and the mean age of the patients is significantly higher (84.3 ± 5.1 years). This finding aligns with those reported in the literature indicating that age-related bone loss exacerbates fracture susceptibility, particularly in the proximal femur 2 , 15 , 17 , 20 . The observed T score disparity (-3.1 ± 0.8 vs. -2.0 ± 0.7, p < 0.001) further emphasizes the need for aggressive osteoporosis management in this population. Temporal Pattern of Contralateral Fractures The mean latency period of 14.3 ± 3.8 months for contralateral fractures suggests a critical window for secondary prevention. This temporal pattern may reflect the combined effects of postsurgical bone remodeling, altered weight-bearing mechanics, and potential delays in achieving optimal BMD through pharmacological intervention 18 , 19 . The clustering of contralateral hip fractures between 9 and 20 months postoperatively warrants the consideration of extended monitoring protocols beyond the conventional 12-month follow-up period 17 , 18 , 19 , 20 . Biomechanical Factors The significantly greater hip flexor peak torque deficit in the contralateral fracture group (22.5% ± 5.3% vs. 14.6% ± 4.1%, p = 0.047) highlights the biomechanical consequences of muscular imbalance. This deficit may contribute to altered gait patterns and increased fall risk, creating a vicious cycle of instability and fracture susceptibility (OR = 2.2) 18,20 . The integration of targeted hip flexor strengthening into rehabilitation protocols may mitigate these risks 20 . Protocol-Specific Rehabilitation Outcomes Our protocol-specific approach, which differentiates between PFNA fixation and arthroplasty patients, demonstrated the importance of tailored rehabilitation strategies 13 , 18 , 19 , 20 , 22 , 23 . The immediate weight-bearing protocol for arthroplasty patients, contingent upon achieving MMT grade IV quadriceps strength, appeared to facilitate earlier functional recovery without compromising surgical outcomes 20 , 23 . Conversely, the protected weight-bearing regimen for PFNA patients likely contributed to the observed fracture consolidation rates 18 , 22 , 23 . Multivariate Regression Analysis of Risk Factors Preliminary multivariate analysis revealed three independent predictors of contralateral fracture risk 18 : age ≥ 80 years (OR = 1.08, 95% CI: 1.02, 1.15), BMD ≤ 0.5 (OR = 0.32, 95% CI: 0.11, 0.89), T score ≤ -2.5 (OR = 1.45, 95% CI: 1.10–1.92), and hip flexor deficit ≥ 20% (OR = 2.2, 95% CI: 1.25–3.86). These findings underscore the multifactorial nature of contralateral hip fracture risk and the need for comprehensive risk assessment tools 2 , 16 , 17 , 18 , 20 , 24 , 25 . Longitudinal Analysis of Functional Recovery The Harris Hip Score (HHS), while widely used, has notable limitations, including subjectivity in patient-reported outcomes, insensitivity to subtle functional changes 7 , 9 , and inadequate assessment of physical activity levels, particularly muscle strength 9 . These limitations underscore the need for complementary assessment tools in high-risk populations. The lack of significant HHS differences between groups (Table 2 ) likely reflects its limited sensitivity for detecting subtle functional deficits, as previously documented 7 , 9 . Consequently, researchers and clinicians should consider alternative or supplementary scoring systems when evaluating hip-related outcomes. Subgroup Analysis Based on Fracture Classification The comparable contralateral fracture rates between intertrochanteric (10.9%) and femoral neck fractures (10.0%) suggest that fracture morphology may be less predictive of contralateral fracture risk than systemic factors such as BMD and muscular function. However, the small subgroup sizes and single-center study design limit definitive conclusions, warranting larger-scale investigations 18 , 19 . Potential measurement errors in hip flexor strength assessment and a follow-up period limited to 20 months, which may limit generalizability. Clinical Implications These findings not only advance risk stratification for contralateral hip fractures but also highlight broader implications for geriatric musculoskeletal health. The interplay between muscle imbalance and bone fragility may extend to other fragility fractures (e.g., vertebral or distal radius fractures), suggesting a unified framework for sarcopenia-osteoporosis management in aging populations. Furthermore, integrating biomechanical biomarkers (e.g., muscle deficit quantification) with systemic inflammatory profiles could catalyze interdisciplinary collaborations spanning orthopedics, geriatrics, and rehabilitation medicine. To bridge current evidence gaps, future research should prioritize three avenues: (1) cost-effectiveness analyses of population-level osteoporosis screening informed by fracture biomechanical risk, (2) development of AI-driven predictive models that synthesize radiological, biochemical, and functional mobility data, and (3) clinical trials evaluating whether neuromuscular re-education protocols—successful in stroke rehabilitation—can be adapted to mitigate post-fracture imbalance. Such translational efforts may redefine preventive care paradigms beyond traditional bone-centric approaches. Declarations Competing Interests : The authors declare that they have no competing interests. Funding Statement : This study was supported by the National High Level Hospital Clinical Research Funding (No. 2023-NHLHCRF-YYPPLC-ZR-12), the Elite Medical Professionals Project of China-Japan Friendship Hospital (NO. ZRJY2023-QM29), and the China-Japan Friendship Hospital Self-selected Project (NO. 2023-HX-46). Authors’ Contributions : HY designed the study; YY analyzed the data; RG collected the data; LS/FS performed the statistics; YC supervised the study. Data availability statement : The datasets generated and/or analysed during the current study are available in the figshare repository, https://doi.org/10.6084/m9.figshare.28620911 is fully functional and accessible. Acknowledgments : We thank the staff of China-Japan Friendship Hospital for their assistance in data collection. References Lau JC. Patient characteristics and risk of subsequent contralateral hip fracture after surgical management of first fracture. Injury. 2014 Oct;45(10):1620-3. doi: 10.1016/j.injury.2014.06.015. Leslie WD. Osteoporosis epidemiology 2013: implications for diagnosis, risk assessment, and treatment. Curr Opin Rheumatol. 2014 Jul;26(4):440-6. doi: 10.1097/BOR.0000000000000064. 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JBJS Am. 2003 Sep;85(9):1673-81. doi: 10.2106/00004623-200309000-00004. Kanis JA, Johnell O, Oden A, Johansson H, McCloskey E. FRAX and the assessment of fracture probability in men and women from the UK. Osteoporos Int. 2008 Apr;19(4):385-97. doi: 10.1007/s00198-007-0543-5. Compston J, Cooper A, Cooper C, Gittoes N, Gregson C, Harvey N, Hope S, Kanis JA, McCloskey EV, Poole KES, Reid DM, Selby P, Thompson F, Thurston A, Vine N; National Osteoporosis Guideline Group (NOGG). UK clinical guideline for the prevention and treatment of osteoporosis. Arch Osteoporos. 2017 Dec;12(1):43. doi: 10.1007/s11657-017-0324-5. Hardcastle P, Nade S. The significance of the Trendelenburg test. J Bone Joint Surg Br. 1985;67-B (5):741-6. Additional Declarations No competing interests reported. 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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-6144656","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":433780449,"identity":"7e782e6f-9939-4a39-becd-15ea0bf8fc55","order_by":0,"name":"Huan Yang","email":"","orcid":"","institution":"China-Japan Friendship Hospital","correspondingAuthor":false,"prefix":"","firstName":"Huan","middleName":"","lastName":"Yang","suffix":""},{"id":433780450,"identity":"fa59c531-1cd3-4aae-9f0b-d194c418fa30","order_by":1,"name":"Yusong Yuan","email":"","orcid":"","institution":"China-Japan Friendship Hospital","correspondingAuthor":false,"prefix":"","firstName":"Yusong","middleName":"","lastName":"Yuan","suffix":""},{"id":433780451,"identity":"581f6316-1ea6-4803-ad1c-09231556628b","order_by":2,"name":"Ruidong Ge","email":"","orcid":"","institution":"China-Japan Friendship Hospital","correspondingAuthor":false,"prefix":"","firstName":"Ruidong","middleName":"","lastName":"Ge","suffix":""},{"id":433780452,"identity":"70cccefe-1367-4750-a70c-7185ac48c6c4","order_by":3,"name":"Lei Shi","email":"","orcid":"","institution":"China-Japan Friendship Hospital","correspondingAuthor":false,"prefix":"","firstName":"Lei","middleName":"","lastName":"Shi","suffix":""},{"id":433780453,"identity":"2ba2bfe8-f7c5-4317-b158-9cd831e385ac","order_by":4,"name":"Fangda Si","email":"","orcid":"","institution":"China-Japan Friendship Hospital","correspondingAuthor":false,"prefix":"","firstName":"Fangda","middleName":"","lastName":"Si","suffix":""},{"id":433780454,"identity":"a92a421c-ec26-483d-9bdf-719a4b497e63","order_by":5,"name":"Ying Chen","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAs0lEQVRIiWNgGAWjYLACxgYbHn7+BtK0pMlIzjhAmpbDNgYNCUSq5p+R/uwz747zPAYMBxg/fMwhQovEjYTk2bxnbvOYMzcwS87cRoQWA4mEw8y8bbd5LBsOsDHzEqclsRmo5RyPwYEEorUkMwO1HCBBi8SZZ8yMc9uSeSRnHGwmzi/87emPGd622dnz8zcf/PCRGC0MAgkMTDxgFmMDMepB1hxgYPxBpNpRMApGwSgYoQAAUIQzwtDXBGQAAAAASUVORK5CYII=","orcid":"","institution":"China-Japan Friendship Hospital","correspondingAuthor":true,"prefix":"","firstName":"Ying","middleName":"","lastName":"Chen","suffix":""}],"badges":[],"createdAt":"2025-03-03 09:23:18","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6144656/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6144656/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":79258277,"identity":"da266312-9f17-4d59-a02e-1a9184b88a8c","added_by":"auto","created_at":"2025-03-26 09:10:05","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":12901,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eKaplan-Meier Survival Curve for Contralateral Hip Fracture Incidence\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe Kaplan-Meier curve illustrates the cumulative incidence of contralateral hip fractures over a 20-month follow-up period in elderly patients following surgical treatment of primary hip fractures. The x-axis represents time in months, and the y-axis shows the cumulative survival probability (i.e., the proportion of patients without contralateral fractures). The curve demonstrates a gradual decline in survival probability, with a cumulative incidence of 10.4% at 20 months. Censored data points (indicated by \"+\" symbols) represent patients who experienced a contralateral hip fracture. This analysis highlights the temporal pattern of contralateral fracture risk, emphasizing the need for extended monitoring and secondary prevention strategies beyond the first-year post-surgery.\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-6144656/v1/20619bbdee1099af6aaf42c6.png"},{"id":83112339,"identity":"9fb39c93-cf11-4b1a-b7c3-c297ec055611","added_by":"auto","created_at":"2025-05-20 07:32:07","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":947629,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6144656/v1/6f315f99-f518-4f65-bdd3-108cbe447d94.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Risk Factors and Predictors of Contralateral Hip Fracture After Surgical Treatment in Elderly Patients","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe increasing prevalence of osteoporotic hip fractures in aging populations has drawn significant attention to contralateral hip fractures, which occur in 6.8\u0026ndash;16.0% of patients with osteoporotic hip fractures \u003csup\u003e[1,16,17]\u003c/sup\u003e. While previous research has focused predominantly on demographic and skeletal factors \u003csup\u003e[1,3,18]\u003c/sup\u003e, emerging evidence underscores the importance of biomechanical contributors, particularly postural instability and muscle weakness \u003csup\u003e[2]\u003c/sup\u003e. The aim of this study was to combine biomechanical (hip flexor strength) and skeletal (BMD) parameters to identify multifactorial predictors of contralateral fractures. To our knowledge, this is the first prospective cohort study to integrate both biomechanical (hip flexor strength) and skeletal (BMD) parameters in the prediction of contralateral hip fractures.\u003c/p\u003e\n\u003ch3\u003eStudy Objectives and Design\u003c/h3\u003e\n\u003cp\u003eThe investigation focused on systematically evaluating biomechanical, biochemical, and functional parameters, including 1) bone quality metrics (BMD and T scores via DXA); 2) neuromuscular functional capacity (hip flexor strength quantified through isokinetic dynamometry); 3) clinical outcomes (Harris Hip Scores); and 4) demographic/operative characteristics. A standardized data collection protocol was implemented across perioperative hospitalization and postdischarge follow-up (6-month intervals) to ensure longitudinal validity.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cp\u003eConsecutive patients who underwent surgical management for low-energy hip fractures at our Level I Trauma Center (January 2022-December 2023) and met the following criteria were included: 1. Age\u0026thinsp;\u0026ge;\u0026thinsp;65 years with low-energy trauma (fall from standing height); 2. Radiographically confirmed intertrochanteric (AO/OTA 31-A; n\u0026thinsp;=\u0026thinsp;55) or femoral neck fractures (Garden II-IV; n\u0026thinsp;=\u0026thinsp;60); and 3. Independent ambulation status prior to the fracture. Furthermore, patients were excluded if they met any of the following criteria: nonsurgical candidate, pathological fracture, neurological/musculoskeletal comorbidity, or visual impairment (best-corrected acuity\u0026thinsp;\u0026lt;\u0026thinsp;20/40). Postoperative Protocol: All patients received standardized anti-osteoporosis therapy and procedure-specific rehabilitation. In particular, in cases of PFNA fixation (n\u0026thinsp;=\u0026thinsp;72), protected weight-bearing was implemented for \u0026ge;\u0026thinsp;6 weeks, and in cases of arthroplasty (n\u0026thinsp;=\u0026thinsp;43), immediate full weight-bearing post quadriceps- strength assessment (MMT grade IV) was implemented.\u003c/p\u003e\n\u003ch3\u003eEthical Compliance Statement\u003c/h3\u003e\n\u003cp\u003eThis study was approved by the Ethics Committee of China-Japan Friendship Hospital (Approval No. 2023-KY-145), and written informed consent was obtained from all participants. All procedures involving human subjects were conducted in strict accordance with the ethical standards of the Declaration of Helsinki (2013 revision), the International Council for Harmonisation (ICH) Guidelines for Good Clinical Practice (GCP), and institutional review board (IRB) policies. Patient confidentiality and data anonymity were rigorously maintained throughout the study.\u003c/p\u003e\n\u003ch3\u003eOutcome assessment\u003c/h3\u003e\n\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eOperative Protocol\u003c/h2\u003e \u003cp\u003eSurgical procedures followed standard protocols for intertrochanteric fractures (PFNA fixation) and femoral neck fractures (hemiarthroplasty/THA).\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003ePostoperation Protocol\u003c/h3\u003e\n\u003cp\u003eAll enrolled patients were routinely administered analgesics, anticoagulants and anti-osteoporosis medications according to standardized protocols. On postoperative day 2, targeted rehabilitation exercises focusing on quadriceps femoris activation, with particular emphasis on the vastus medialis oblique (VMO), were initiated. Patients were permitted to commence partial weight-bearing ambulation with full assistive support only after achieving grade IV muscle strength in the quadriceps femoris, as assessed by manual muscle testing (MMT).\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eFollow-up\u003c/h2\u003e \u003cp\u003eAt the 6-month postoperative follow-up, comprehensive functional assessments were performed. Hip abductor function was evaluated using the standardized Trendelenburg test\u003csup\u003e\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u003c/sup\u003e, with positive findings (inability to maintain pelvic alignment during a single-leg stance), resulting in study exclusion. Hip flexor strength, represented by peak torque (PT), was measured using the BIODEX SYSTEM 4 PRO (Biodex Medical Systems, Inc., Shirley, NY) under the supervision of licensed physical therapists. The testing protocol involved a unilateral stance with rapid contralateral leg elevation, measuring peak torque (ft-lb) and automatically calculating torque deficit percentages. Deficit severity was categorized as follows: (1) 1\u0026ndash;10%, within normal limits; (2) 11\u0026ndash;20%, indicating the need for rehabilitation; and (3)\u0026thinsp;\u0026gt;\u0026thinsp;20%, representing significant functional impairment. All measurements were recorded immediately postassessment to ensure data integrity and reliability.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eStudy Groups\u003c/h3\u003e\n\u003cp\u003eThe study population was stratified into two comparative cohorts on the basis of fracture characteristics: Group A (n\u0026thinsp;=\u0026thinsp;12) consisted of patients presenting with contralateral hip fractures, and Group B (n\u0026thinsp;=\u0026thinsp;103) comprised patients without contralateral involvement. A comprehensive comparative analysis was conducted between these cohorts. The variables in this analysis comprised multiple demographic and clinical parameters, including but not limited to age distribution, sex ratio, fracture classification according to the AO/OTA system, bone mineral density (BMD) in the hip region, T scores derived from dual-energy X-ray absorptiometry (DEXA) scans, length of hospital stay, Harris Hip Score (HHS) for functional assessment, and isokinetic measurements of hip flexor peak torque with corresponding deficit calculations.\u003c/p\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Analysis\u003c/h2\u003e \u003cp\u003eThe sample size of 115 was determined on the basis of a power analysis (α\u0026thinsp;=\u0026thinsp;0.05, β\u0026thinsp;=\u0026thinsp;0.20) to detect a 15% difference between groups. All the statistical analyses were performed using PASW Statistics 21.0 software (IBM Corp., Armonk, NY, USA). Intergroup comparisons between Group A and Group B were conducted for multiple variables. Continuous variables, including age, time interval from injury to surgical intervention, length of hospital stay, bone mineral density (BMD), T score, Harris hip score (HHS), and isokinetic measurements of hip flexor peak torque (with associated deficit values), were analyzed using independent samples t tests following the confirmation of a normal distribution by means of Shapiro\u0026ndash;Wilk tests. Categorical variables, such as sex distribution and fracture classification, were evaluated using Pearson's chi-square (χ2) test or Fisher's exact test, as appropriate. Missing data, which accounted for less than 5% of the total dataset, were excluded from the analysis under the assumption of being missing completely at random (MCAR). Variables demonstrating statistically significant differences (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05) in the univariate analysis were subsequently incorporated into multivariate logistic regression models to identify independent predictors. A two-tailed p value of \u0026lt;\u0026thinsp;0.05 was considered statistically significant for all analyses.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eConsecutive patients (N\u0026thinsp;=\u0026thinsp;115) enrolled while 3 patients were excluded due to their request to withdraw consent. Contralateral fractures occurred in 10.4% of the patients (12/115) at a mean latency of 14.3\u0026thinsp;\u0026plusmn;\u0026thinsp;3.8 months. Compared with the patients in Group B, those in Group A (contralateral fractures) were significantly older (84.3 vs. 79.1 years, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.015), had a lower BMD (0.68 vs. 0.77 g/cm\u0026sup2;, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.021), and had higher proportion of cases of hip flexor deficit (22.5% vs. 14.6%, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.032) (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Multivariate analysis revealed that age, male sex, T score, BMD, and hip flexor deficit were independent risk factors (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003ePostoperative Outcomes and Fracture Epidemiology\u003c/h2\u003e \u003cp\u003eThe mean hospitalization duration was 8.7\u0026thinsp;\u0026plusmn;\u0026thinsp;3.2 days (range: 3\u0026ndash;22) in the prospective cohort, and the injury-to-surgery interval was 1.8\u0026thinsp;\u0026plusmn;\u0026thinsp;0.9 days (range: 1\u0026ndash;3), with no intergroup differences (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05). Systematic follow-up over 6\u0026ndash;20 months revealed a contralateral fracture incidence of 10.4% (12/115), indicating a balanced sex ratio, comprising 6 males and 6 females, representing an equal proportion (50%) in Group A. Fracture patterns were comparable between intertrochanteric (10.9%, 6/55) and femoral neck fractures (10.0%, 6/60). Contralateral hip fractures occurred at a mean latency of 14.3\u0026thinsp;\u0026plusmn;\u0026thinsp;3.8 months postoperatively (range: 9\u0026ndash;20).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eSurgical and Rehabilitation Protocols\u003c/h2\u003e \u003cp\u003eAll patients received standardized anti-osteoporosis therapy (calcium/alfacalcidol) and procedure-specific rehabilitation:\u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003ePFNA fixation\u003c/b\u003e (n\u0026thinsp;=\u0026thinsp;72): Protected weight-bearing for \u0026ge;\u0026thinsp;6 weeks with progressive quadriceps strengthening.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003eArthroplasty\u003c/b\u003e (n\u0026thinsp;=\u0026thinsp;43): Immediate full weight-bearing upon achieving MMT grade IV quadriceps strength. Postoperative hip mobility was restricted to -10\u0026deg;\u0026ndash;90\u0026deg; during the first month, supplemented by supervised isometric exercises initiated within 24 hours postoperatively.\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eComparative Analysis of Risk Factors\u003c/h2\u003e \u003cp\u003eUnivariate analysis revealed significant disparities between the contralateral fracture (Group A, n\u0026thinsp;=\u0026thinsp;12) and control (Group B, n\u0026thinsp;=\u0026thinsp;103) cohorts (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eUnivariate analysis of risk factors\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" style=\"width: 35.2442%;\"\u003e\n \u003cp\u003eParameter\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"width: 15.7113%;\"\u003e\n \u003cp\u003eGroup A\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"width: 15.7113%;\"\u003e\n \u003cp\u003eGroup B\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"width: 33.3333%;\"\u003e\n \u003cp\u003eStatistical Significance\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 35.2442%;\"\u003e\n \u003cp\u003eAge (years)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 15.7113%;\"\u003e\n \u003cp\u003e84.3\u0026thinsp;\u0026plusmn;\u0026thinsp;5.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 15.7113%;\"\u003e\n \u003cp\u003e79.1\u0026thinsp;\u0026plusmn;\u0026thinsp;6.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 33.3333%;\"\u003e\n \u003cp\u003e\u003cem\u003et\u003c/em\u003e =-2.16 \u003cem\u003ep\u003c/em\u003e =0.03\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 35.2442%;\"\u003e\n \u003cp\u003eBMD (g/cm\u0026sup2;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 15.7113%;\"\u003e\n \u003cp\u003e0.68\u0026thinsp;\u0026plusmn;\u0026thinsp;0.11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 15.7113%;\"\u003e\n \u003cp\u003e0.77\u0026thinsp;\u0026plusmn;\u0026thinsp;0.09\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 33.3333%;\"\u003e\n \u003cp\u003e\u003cem\u003et\u003c/em\u003e = 2.15 \u003cem\u003ep\u003c/em\u003e =0.03\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 35.2442%;\"\u003e\n \u003cp\u003eT score\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 15.7113%;\"\u003e\n \u003cp\u003e-3.1\u0026thinsp;\u0026plusmn;\u0026thinsp;0.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 15.7113%;\"\u003e\n \u003cp\u003e-2.0\u0026thinsp;\u0026plusmn;\u0026thinsp;0.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 33.3333%;\"\u003e\n \u003cp\u003e\u003cem\u003et\u003c/em\u003e = 4.94 \u003cem\u003ep\u003c/em\u003e \u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 35.2442%;\"\u003e\n \u003cp\u003ePeak torque (uninvolved)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 15.7113%;\"\u003e\n \u003cp\u003e58.7\u0026thinsp;\u0026plusmn;\u0026thinsp;7.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 15.7113%;\"\u003e\n \u003cp\u003e63.2\u0026thinsp;\u0026plusmn;\u0026thinsp;8.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 33.3333%;\"\u003e\n \u003cp\u003e\u003cem\u003et\u003c/em\u003e\u0026thinsp;=\u0026thinsp;2.15 \u003cem\u003ep\u003c/em\u003e =0.03\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" style=\"width: 35.2442%;\"\u003e\n \u003cp\u003eHip flexor deficit (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 15.7113%;\"\u003e\n \u003cp\u003e22.5\u0026thinsp;\u0026plusmn;\u0026thinsp;5.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\" style=\"width: 15.7113%;\"\u003e\n \u003cp\u003e14.6\u0026thinsp;\u0026plusmn;\u0026thinsp;4.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"width: 33.3333%;\"\u003e\n \u003cp\u003e\u003cem\u003et\u003c/em\u003e = -2.01 \u003cem\u003ep\u003c/em\u003e =0.047\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003cp\u003eBMD: Bone mineral density; PFNA: Proximal femoral nail antirotation; MMT: Manual muscle testing\u003c/p\u003e \u003cp\u003eNo significant differences were observed between Group A and Group B in terms of sex, length of hospital stay, fracture type, Harris score, or involved hip flexor peak torque (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003e\u003cb\u003eComparison of Clinical Characteristics between Group A and Group B\u003c/b\u003e\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariable\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eGroup A (n\u0026thinsp;=\u0026thinsp;12)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eGroup B (n\u0026thinsp;=\u0026thinsp;103)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eStatistical Value\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003ep\u003c/em\u003e value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSex (Male/Female)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4 (33.3%)/8(66.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e29 (28.2%)/74(71.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eχ\u0026sup2;=3.45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.06\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLength of Hospital Stay (days)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e9.8\u0026thinsp;\u0026plusmn;\u0026thinsp;4.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8.5\u0026thinsp;\u0026plusmn;\u0026thinsp;3.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003et\u003c/em\u003e=-0.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.44\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFracture Type\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e- Intertrochanteric Fracture\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5 (41.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e50 (48.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" morerows=\"1\" nameend=\"c5\" namest=\"c4\" rowspan=\"2\"\u003e \u003cp\u003eχ\u0026sup2;=6.356 0.70\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e- Femoral Neck Fracture\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7 (58.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e53 (51.5%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHarris Score\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e81.0\u0026thinsp;\u0026plusmn;\u0026thinsp;10.88\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e79.95\u0026thinsp;\u0026plusmn;\u0026thinsp;10.73\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e\u003cem\u003et\u003c/em\u003e=-0.54 0.60\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePeak Torque (involved)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e55.1\u0026thinsp;\u0026plusmn;\u0026thinsp;7.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e52.8\u0026thinsp;\u0026plusmn;\u0026thinsp;6.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e\u003cem\u003et\u003c/em\u003e=-1.23 0.22\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe logistic regression analysis revealed that age, male sex, lower T scores, reduced BMD, and greater hip flexor deficit were significant risk factors for contralateral hip fractures. These findings highlight the importance of addressing both skeletal and biomechanical factors in the prevention and management of contralateral hip fractures in elderly patients (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\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 \u003cp\u003e\u003cb\u003eMultivariate Logistic Regression Analysis of Independent Risk Factors for Contralateral Hip Fractures\u003c/b\u003e\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariable\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eβ\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSE\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003ep\u003c/em\u003e value\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eOR\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eCI\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"1\" nameend=\"c7\" namest=\"c7\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.072\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e0.012\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e1.08\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e[1.02,1.15]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c7\" namest=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eSex\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.210\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.603\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1.23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e[0.56, 2.71]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eHospital Stays\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-0.015\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.038\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.692\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e[0.91,1.06]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eFracture type\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.102\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.189\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.589\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e[0.76,1.61]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eBMD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-1.139\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.518\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e0.028\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e0.32\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e[0.11,0.89]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eT score\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.372\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.140\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e0.008\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e1.45\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e[1.10,1.92]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c7\" namest=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHarris score\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-0.008\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.014\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.567\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.99\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e[0.97,1.02]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c7\" namest=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePT (Involved)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-0.015\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.454\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e[0.94,1.03]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c7\" namest=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePT (Uninvolved)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-0.021\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.018\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.244\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.99\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e[0.94,1.02]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c7\" namest=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePT deficit (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.788\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.286\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e0.006\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e2.2\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e[1.25,3.86]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c7\" namest=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"7\"\u003e\u003cem\u003eBMD: Bone mineral density; PT: Peak torque; PT: deficit: Peak torque deficit;\u003c/em\u003e\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eKaplan‒Meier analysis revealed a cumulative contralateral fracture incidence of 10.4% at 20 months (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe Kaplan-Meier curve illustrates the cumulative incidence of contralateral hip fractures over a 20-month follow-up period in elderly patients following surgical treatment of primary hip fractures. The x-axis represents time in months, and the y-axis shows the cumulative survival probability (i.e., the proportion of patients without contralateral fractures). The curve demonstrates a gradual decline in survival probability, with a cumulative incidence of 10.4% at 20 months. Censored data points (indicated by \"+\" symbols) represent patients who experienced a contralateral hip fracture. This analysis highlights the temporal pattern of contralateral fracture risk, emphasizing the need for extended monitoring and secondary prevention strategies beyond the first-year post-surgery.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003eFactors Associated with Contralateral Hip Fractures\u003c/h2\u003e \u003cp\u003eBone mineral density (BMD) measurements revealed a mean of 0.68\u0026thinsp;\u0026plusmn;\u0026thinsp;0.11 in Group A and 0.77\u0026thinsp;\u0026plusmn;\u0026thinsp;0.09 in Group B (\u003cem\u003et\u003c/em\u003e\u0026thinsp;=\u0026thinsp;2.15, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.03), whereas T scores of -3.1\u0026thinsp;\u0026plusmn;\u0026thinsp;0.8 in Group A and \u0026minus;\u0026thinsp;2.0\u0026thinsp;\u0026plusmn;\u0026thinsp;0.7 in Group B indicated more severe osteoporosis in patients with contralateral fractures (\u003cem\u003et\u003c/em\u003e\u0026thinsp;=\u0026thinsp;4.94, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001). The musculoskeletal assessment revealed that the percent deficit in hip flexor strength was significantly greater in Group A (22.5\u0026thinsp;\u0026plusmn;\u0026thinsp;5.3) than in Group B (14.6\u0026thinsp;\u0026plusmn;\u0026thinsp;4.1); \u003cem\u003et\u003c/em\u003e = -2.01, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.047), suggesting greater bilateral muscle imbalance in patients with contralateral fractures.\u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe synergistic effect of advanced age and reduced BMD underscores the critical role of osteoporosis management in contralateral fracture prevention \u003csup\u003e[2,15,17]\u003c/sup\u003e, as evidenced by our findings (Group A: BMD 0.68 vs. Group B: 0.77 g/cm\u0026sup2;, p\u0026thinsp;=\u0026thinsp;0.03). A lower T score (-3.1 vs. -2.0, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001) aligns with prior evidence that age-related bone loss exacerbates fracture risk \u003csup\u003e[20]\u003c/sup\u003e. The mean latency period of 14.3 months postoperatively highlights a critical window for secondary prevention, potentially linked to delayed bone remodeling and altered weight-bearing mechanics \u003csup\u003e[18,19]\u003c/sup\u003e. Extended follow-up protocols beyond 12 months may improve monitoring efficacy. Notably, hip flexor strength imbalance (OR\u0026thinsp;=\u0026thinsp;2.2) emerged as a stronger biomechanical predictor, suggesting targeted rehabilitation to mitigate gait instability and fall risk \u003csup\u003e[20]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe findings of this study provide critical insights into the multifactorial nature of contralateral hip fractures in elderly patients, highlighting several key areas for clinical consideration and future research.\u003c/p\u003e \u003cdiv id=\"Sec18\" class=\"Section2\"\u003e \u003ch2\u003eAge/BMD interaction\u003c/h2\u003e \u003cp\u003eThe significant correlation between advanced age and reduced bone mineral density (BMD) underscores the synergistic effect of these factors in increasing contralateral hip fracture risk\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e,\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e,\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e,\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e,\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e,\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e. Our data show that in patients with contralateral fractures, compared with those of the controls, the BMD values of the patients are significantly lower (0.68\u0026thinsp;\u0026plusmn;\u0026thinsp;0.11 g/cm\u0026sup2;), and the mean age of the patients is significantly higher (84.3\u0026thinsp;\u0026plusmn;\u0026thinsp;5.1 years). This finding aligns with those reported in the literature indicating that age-related bone loss exacerbates fracture susceptibility, particularly in the proximal femur \u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e,\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e,\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e,\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e. The observed T score disparity (-3.1\u0026thinsp;\u0026plusmn;\u0026thinsp;0.8 vs. -2.0\u0026thinsp;\u0026plusmn;\u0026thinsp;0.7, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001) further emphasizes the need for aggressive osteoporosis management in this population.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec19\" class=\"Section2\"\u003e \u003ch2\u003eTemporal Pattern of Contralateral Fractures\u003c/h2\u003e \u003cp\u003eThe mean latency period of 14.3\u0026thinsp;\u0026plusmn;\u0026thinsp;3.8 months for contralateral fractures suggests a critical window for secondary prevention. This temporal pattern may reflect the combined effects of postsurgical bone remodeling, altered weight-bearing mechanics, and potential delays in achieving optimal BMD through pharmacological intervention\u003csup\u003e\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e,\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e. The clustering of contralateral hip fractures between 9 and 20 months postoperatively warrants the consideration of extended monitoring protocols beyond the conventional 12-month follow-up period\u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e,\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e,\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e,\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec20\" class=\"Section2\"\u003e \u003ch2\u003eBiomechanical Factors\u003c/h2\u003e \u003cp\u003eThe significantly greater hip flexor peak torque deficit in the contralateral fracture group (22.5% \u0026plusmn; 5.3% vs. 14.6% \u0026plusmn; 4.1%, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.047) highlights the biomechanical consequences of muscular imbalance. This deficit may contribute to altered gait patterns and increased fall risk, creating a vicious cycle of instability and fracture susceptibility (OR\u0026thinsp;=\u0026thinsp;2.2)\u003csup\u003e18,20\u003c/sup\u003e. The integration of targeted hip flexor strengthening into rehabilitation protocols may mitigate these risks\u003csup\u003e\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec21\" class=\"Section2\"\u003e \u003ch2\u003eProtocol-Specific Rehabilitation Outcomes\u003c/h2\u003e \u003cp\u003eOur protocol-specific approach, which differentiates between PFNA fixation and arthroplasty patients, demonstrated the importance of tailored rehabilitation strategies\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e,\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e,\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e,\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e,\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e,\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u003c/sup\u003e. The immediate weight-bearing protocol for arthroplasty patients, contingent upon achieving MMT grade IV quadriceps strength, appeared to facilitate earlier functional recovery without compromising surgical outcomes\u003csup\u003e\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e,\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u003c/sup\u003e. Conversely, the protected weight-bearing regimen for PFNA patients likely contributed to the observed fracture consolidation rates\u003csup\u003e\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e,\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e,\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec22\" class=\"Section2\"\u003e \u003ch2\u003eMultivariate Regression Analysis of Risk Factors\u003c/h2\u003e \u003cp\u003ePreliminary multivariate analysis revealed three independent predictors of contralateral fracture risk\u003csup\u003e\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u003c/sup\u003e: age\u0026thinsp;\u0026ge;\u0026thinsp;80 years (OR\u0026thinsp;=\u0026thinsp;1.08, 95% CI: 1.02, 1.15), BMD\u0026thinsp;\u0026le;\u0026thinsp;0.5 (OR\u0026thinsp;=\u0026thinsp;0.32, 95% CI: 0.11, 0.89), T score \u0026le; -2.5 (OR\u0026thinsp;=\u0026thinsp;1.45, 95% CI: 1.10\u0026ndash;1.92), and hip flexor deficit\u0026thinsp;\u0026ge;\u0026thinsp;20% (OR\u0026thinsp;=\u0026thinsp;2.2, 95% CI: 1.25\u0026ndash;3.86). These findings underscore the multifactorial nature of contralateral hip fracture risk and the need for comprehensive risk assessment tools\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e,\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e,\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e,\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e,\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e,\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cdiv id=\"Sec23\" class=\"Section3\"\u003e \u003ch2\u003eLongitudinal Analysis of Functional Recovery\u003c/h2\u003e \u003cp\u003eThe Harris Hip Score (HHS), while widely used, has notable limitations, including subjectivity in patient-reported outcomes, insensitivity to subtle functional changes \u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e,\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e, and inadequate assessment of physical activity levels, particularly muscle strength \u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e. These limitations underscore the need for complementary assessment tools in high-risk populations. The lack of significant HHS differences between groups (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e) likely reflects its limited sensitivity for detecting subtle functional deficits, as previously documented \u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e,\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e. Consequently, researchers and clinicians should consider alternative or supplementary scoring systems when evaluating hip-related outcomes.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec24\" class=\"Section2\"\u003e \u003ch2\u003eSubgroup Analysis Based on Fracture Classification\u003c/h2\u003e \u003cp\u003eThe comparable contralateral fracture rates between intertrochanteric (10.9%) and femoral neck fractures (10.0%) suggest that fracture morphology may be less predictive of contralateral fracture risk than systemic factors such as BMD and muscular function. However, the small subgroup sizes and single-center study design limit definitive conclusions, warranting larger-scale investigations\u003csup\u003e\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e,\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e. Potential measurement errors in hip flexor strength assessment and a follow-up period limited to 20 months, which may limit generalizability.\u003c/p\u003e \u003cdiv id=\"Sec25\" class=\"Section3\"\u003e \u003ch2\u003eClinical Implications\u003c/h2\u003e \u003cp\u003eThese findings not only advance risk stratification for contralateral hip fractures but also highlight broader implications for geriatric musculoskeletal health. The interplay between muscle imbalance and bone fragility may extend to other fragility fractures (e.g., vertebral or distal radius fractures), suggesting a unified framework for sarcopenia-osteoporosis management in aging populations. Furthermore, integrating biomechanical biomarkers (e.g., muscle deficit quantification) with systemic inflammatory profiles could catalyze interdisciplinary collaborations spanning orthopedics, geriatrics, and rehabilitation medicine. To bridge current evidence gaps, future research should prioritize three avenues: (1) cost-effectiveness analyses of population-level osteoporosis screening informed by fracture biomechanical risk, (2) development of AI-driven predictive models that synthesize radiological, biochemical, and functional mobility data, and (3) clinical trials evaluating whether neuromuscular re-education protocols\u0026mdash;successful in stroke rehabilitation\u0026mdash;can be adapted to mitigate post-fracture imbalance. Such translational efforts may redefine preventive care paradigms beyond traditional bone-centric approaches.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eCompeting Interests\u003c/strong\u003e: The authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding Statement\u003c/strong\u003e: This study was supported by the National High Level Hospital Clinical Research Funding (No. 2023-NHLHCRF-YYPPLC-ZR-12), the Elite Medical Professionals Project of China-Japan Friendship Hospital (NO. ZRJY2023-QM29), and the China-Japan Friendship Hospital Self-selected Project (NO. 2023-HX-46).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026rsquo; Contributions\u003c/strong\u003e: HY designed the study; YY analyzed the data; RG collected the data; LS/FS performed the statistics; YC supervised the study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability statement\u003c/strong\u003e: The datasets generated and/or analysed during the current study are available in the figshare repository, https://doi.org/10.6084/m9.figshare.28620911 is fully functional and accessible.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e: We thank the staff of China-Japan Friendship Hospital for their assistance in data collection.\u003c/p\u003e"},{"header":"References","content":"\u003col start=\"1\" type=\"1\"\u003e\n \u003cli\u003eLau JC. Patient characteristics and risk of subsequent contralateral hip fracture after surgical management of first fracture. Injury. 2014 Oct;45(10):1620-3. doi: 10.1016/j.injury.2014.06.015.\u003c/li\u003e\n \u003cli\u003eLeslie WD. Osteoporosis epidemiology 2013: implications for diagnosis, risk assessment, and treatment. Curr Opin Rheumatol. 2014 Jul;26(4):440-6. doi: 10.1097/BOR.0000000000000064.\u003c/li\u003e\n \u003cli\u003eRathbun AM, Magaziner J, Shardell MD, et al. Older men who sustain a hip fracture experience greater declines in bone mineral density at the contralateral hip than non-fracture comparators. Osteoporos Int. 2017 Oct;28(10):2741-8. doi: 10.1007/s00198-017-4280-0.\u003c/li\u003e\n \u003cli\u003eKoot VCM. Evaluation of the Singh index for measuring osteoporosis. JBJS Br. 1996 Sep;78(5):831-4. doi: 10.1302/0301-620X.78B5.0780831.\u003c/li\u003e\n \u003cli\u003eSalo A. Relationship of vitamin D status and cardiometabolic risk factors in children and adolescents. 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Factors influencing length of stay and mortality after first and second hip fractures: an event modeling analysis. J Orthop Trauma. 2013 Feb;27(2):82-6. doi: 10.1097/BOT.0b013e3182694746.\u003c/li\u003e\n \u003cli\u003eLiu S. Risk factors for the second contralateral hip fracture in elderly patients: a systematic review and meta-analysis. Clin Rehabil. 2014 Jul;28(7):15-6. doi: 10.1177/0269215514527593.\u003c/li\u003e\n \u003cli\u003eGregg EW, Pereira MA, Caspersen CJ. Physical activity, falls and fractures among older adults: a review of the epidemiologic evidence. J Am Geriatr Soc. 2000 Aug;48(8):883-93. doi: 10.1111/j.1532-5415.2000.tb06884.x.\u003c/li\u003e\n \u003cli\u003eZidrou C, Vasiliadis AV, Rizou S, Beletsiotis A. Second hip fracture in older adults: Incidence and risk factors. Eur J Orthop Surg Traumatol. 2023 Jul;33(5):1599-606. doi: 10.1007/s00590-022-03309-9.\u003c/li\u003e\n \u003cli\u003eRyg J, Rejnmark L, Overgaard S, Brixen K, Vestergaard P. Hip fracture patients at risk of second hip fracture: a nationwide population-based cohort study of 169,145 cases during 1997\u0026ndash;2001. J Bone Miner Res. 2009 Jul;24(7):1299-307. doi: 10.1359/jbmr.090207.\u003c/li\u003e\n \u003cli\u003eZhao L, Tian S, Sha W, Wang L, Xu Y. Analysis of the clinical characteristics and risk factors associated with contralateral hip fracture after initial hip fracture in elderly patients: a retrospective cohort study. Sci Rep. 2024 Jan;14(1):14292. doi: 10.1038/s41598-024-65165-3.\u003c/li\u003e\n \u003cli\u003eVochteloo AJ, Borger van der Burg BL, R\u0026ouml;ling MA, et al. Contralateral hip fractures and other osteoporosis-related fractures in hip fracture patients: incidence and risk factors. An observational cohort study of 1,229 patients. Arch Orthop Trauma Surg. 2012 Aug;132(8):1191-7. doi: 10.1007/s00402-012-1520-9.\u003c/li\u003e\n \u003cli\u003eFujita T, Takegami Y, Ando K, et al. Risk factors for second hip fracture in elderly patients: an age, sex, and fracture type matched case-control study. Eur J Orthop Surg Traumatol. 2022 Mar;32(3):437-42. doi: 10.1007/s00590-021-02996-0.\u003c/li\u003e\n \u003cli\u003eGade GV, J\u0026oslash;rgensen MG, Ryg J, et al. Development of a multivariable prognostic prediction model for 1-year risk of falling in a cohort of community-dwelling older adults aged 75 years and above (PREFALL). BMC Geriatr. 2021 May;21(1):402. doi: 10.1186/s12877-021-02346-z.\u003c/li\u003e\n \u003cli\u003eParker MJ, Handoll HH. Gamma and other cephalocondylic intramedullary nails versus extramedullary implants for extracapsular hip fractures in adults. Cochrane Database Syst Rev. 2010 Sep 8;(9):CD000093. doi: 10.1002/14651858.CD000093.pub5.\u003c/li\u003e\n \u003cli\u003eBhandari M, Devereaux PJ, Swiontkowski MF, Tornetta P 3rd, Obremskey W, Koval KJ, Nork S, Sprague S, Schemitsch EH, Guyatt GH. Internal fixation compared with arthroplasty for displaced fractures of the femoral neck. A meta-analysis. JBJS\u003cem\u003e\u0026nbsp;\u003c/em\u003eAm. 2003 Sep;85(9):1673-81. doi: 10.2106/00004623-200309000-00004.\u003c/li\u003e\n \u003cli\u003eKanis JA, Johnell O, Oden A, Johansson H, McCloskey E. FRAX and the assessment of fracture probability in men and women from the UK. Osteoporos Int. 2008 Apr;19(4):385-97. doi: 10.1007/s00198-007-0543-5.\u003c/li\u003e\n \u003cli\u003eCompston J, Cooper A, Cooper C, Gittoes N, Gregson C, Harvey N, Hope S, Kanis JA, McCloskey EV, Poole KES, Reid DM, Selby P, Thompson F, Thurston A, Vine N; National Osteoporosis Guideline Group (NOGG). UK clinical guideline for the prevention and treatment of osteoporosis. Arch Osteoporos. 2017 Dec;12(1):43. doi: 10.1007/s11657-017-0324-5.\u003c/li\u003e\n \u003cli\u003eHardcastle P, Nade S. The significance of the Trendelenburg test. J Bone Joint Surg Br. 1985;67-B (5):741-6.\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":"Hip fracture, osteoporosis, bone mineral density, muscle imbalance, rehabilitation, geriatric trauma, secondary prevention","lastPublishedDoi":"10.21203/rs.3.rs-6144656/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6144656/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eBackground: Hip fractures are common in elderly patients, with some experiencing contralateral fractures. \u0026nbsp;Even so, information on predictors of hip fractures in elderly adults is lacking. In this study, we investigated risk factors for contralateral hip fractures after surgical treatment of primary fractures.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eMethods: This was a prospective cohort study of 115 patients aged ≥65 years with low-energy hip fractures. The clinical parameters evaluated included age, sex, bone mineral density (BMD), T score, and hip flexor strength deficit. Patients were stratified into two groups: those with (n=12) and those without contralateral fractures (n=103).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eResults: Contralateral fractures occurred in 10.4% of the patients. Logistic regression revealed thatage (OR=1.08), reduced BMD (OR=0.33), lower T score (OR=1.45), and hip flexor imbalance (OR=2.2) weresignificant predictors.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eConclusion: A multimodal approach that integratesanti-osteoporosis therapy and targeted rehabilitation may reduce contralateral fracture risk in elderly patients.\u003c/p\u003e","manuscriptTitle":"Risk Factors and Predictors of Contralateral Hip Fracture After Surgical Treatment in Elderly Patients","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-03-26 09:02:00","doi":"10.21203/rs.3.rs-6144656/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":"0af7bd5e-32bf-4b81-83c4-e8e7c415002a","owner":[],"postedDate":"March 26th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":46189465,"name":"Health sciences/Medical research"},{"id":46189466,"name":"Health sciences/Risk factors"}],"tags":[],"updatedAt":"2025-05-20T07:23:57+00:00","versionOfRecord":[],"versionCreatedAt":"2025-03-26 09:02:00","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6144656","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6144656","identity":"rs-6144656","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}