Evaluation of Fibula and Talus Position in Patients with Chronic Ankle Instability Using Computed Tomography

Evaluation of Fibula and Talus Position in Patients with Chronic Ankle Instability Using Computed Tomography | 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 Evaluation of Fibula and Talus Position in Patients with Chronic Ankle Instability Using Computed Tomography Jie Wang, Ming-liang Chen, Cheng-yi Gu, Jin-lang Liu, Zhi-hao Duan, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6744677/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 Chronic ankle instability (CAI) is a common sequela of recurrent ankle sprains, yet the role of bony structural changes in its pathogenesis remains debated. This study aimed to evaluate the positional relationships of the fibula and talus in CAI patients using computed tomography (CT). Methods A retrospective cohort study included 50 CAI patients and 50 controls. Axial CT images were analyzed to measure four indices: Axial Malleolar Index (AMI), Intermalleolar Index (IMI), Malleolar Talus Index (MTI), and Midpoint Intermalleolar Index (MIMI). Intra- and inter-observer reliabilities were assessed via intraclass correlation coefficients (ICC). Results Demographic variables (age, gender, BMI) showed no significant intergroup differences. AMI, IMI, and MIMI were comparable between groups ( P > 0.05). However, MTI was significantly reduced in the CAI group ( P < 0.05), suggesting potential external talar rotation. Conclusion CT axial imaging revealed no significant alterations in fibular positioning relative to the talus or tibia in CAI patients. The observed decrease in MTI may indicate talar external rotation, warranting further investigation into its biomechanical implications. Level of Evidence: III. (DIAGNOSTIC, Retrospective cohort study) Chronic ankle instability Talus Fibula Computed tomography Axial imaging Biomechanics Figures Figure 1 Figure 2 Figure 3 Background Ankle sprains are among the most prevalent musculoskeletal injuries, with up to 40% progressing to chronic ankle instability (CAI) [ 1 – 4 ]. CAI is characterized by persistent pain, recurrent giving-way episodes, and functional impairment, often culminating in post-traumatic osteoarthritis[ 5 – 9 ]. While ligamentous laxity is a well-established contributor, emerging evidence implicates bony alignment alterations—particularly fibular malpositioning and talar rotation—as potential etiological factors[ 1 , 9 ]. Conventional diagnostic modalities for CAI include stress radiography and magnetic resonance imaging (MRI) [ 10 , 11 ]. Imaging measurements play a pivotal role in orthopedics and greatly enhance clinical practice [ 12 – 19 ].However, due to inherent biases in subjective questionnaires and physical examinations, results may yield false-positive or false-negative outcomes influenced by variations among different operators and patients. Therefore, the diagnosis of CAI relies heavily on imaging techniques, primarily stress X-rays and magnetic resonance imaging (MRI), which are relatively accurate and crucial as indirect imaging changes also assist in diagnosing CAI. The high incidence of CAI can be attributed to a multifactorial approach, wherein changes in bony structures serve as significant intrinsic anatomical risk factors, including the positioning of the fibula and the rotation of the talus [ 1 , 9 ]. These alterations may contribute to the etiology of recurrent sprains or may be a consequence of CAI, a dynamic process. Previous studies have sparked discussions regarding the positional changes of the talus and fibula in patients with CAI [ 20 , 21 ]. This study is designed to evaluate the positional alterations of the talus and fibula in CAI patients using CT. This study introduces the Midpoint Intermalleolar Index (MIMI), a novel measurement designed to mitigate individual anatomical variability, and evaluates its diagnostic value alongside traditional indices.The purpose of this research is to apply both traditional and novel measurement approaches to more accurately determine the positional variations in the talus and fibula of CAI patients. We hypothesize that there are no substantial changes in the positioning of the talus and fibula in subjects suffering from CAI. Methods Study Design and Participants This study was approved by the Institutional Review Board (IRB) of Affiliated Renhe Hospital of China Three Gorges University[Hospital Name] (Ethics Review No. 2023ky16). The volunteers involved in the study consent to participate in the study. And the written informed consent has been obtained from the volunteers. Selection of Study Subjects A retrospective cohort study was conducted on 50 patients diagnosed with CAI who were treated at our hospital from July 1, 2018, to July 1, 2023, comprising 31 males and 19 females (experimental group). For comparative analysis, a control group was established, including 50 individuals (31 males and 19 females) treated for unrelated conditions such as ankle synovitis, soft tissue injuries, and skin lacerations. These control subjects exhibited no injuries to ankle bones or ligaments and had no history of ankle sprains. Criteria for Inclusion and Exclusion Inclusion criteria [20, 22–24 ] consisted of: (1) recurrent ankle sprains or a sensation of instability; (2) difficulty walking on uneven terrain; (3) at least one enduring symptom like pain, swelling, or weakness; (4) positive outcomes on anterior drawer or talar tilt tests; (5) MRI signs of damage to the anterior talofibular ligament, possibly involving the calcaneofibular ligament; (6) arthroscopic verification of ligament damage; and (7) a Cumberland Ankle Instability Tool (CAIT) score under 24 [ 25 , 26 ]. Exclusion criteria encompassed: (1) previous ankle or lower limb surgery; (2) deformities in adjacent joints or skeletal anomalies including flat feet, high arches, or inward heel rotation; (3) recent ankle sprains, inferior tibiofibular syndesmosis injuries, medial deltoid ligament injuries, or any surrounding bone damage; (4) osteochondral lesions of the talus or cystic bone changes near the ankle; (5) age under 16 or over 45, considering developmental and osteoporotic changes that could affect measurements. Imaging Protocol Philips Ingenuity 128 spiral CT was employed for scanning. Patients were positioned supine with the ankle relaxed. Axial, coronal, and sagittal views were captured. Parameters set included a tube voltage of 120 kV, current of 150 mAs, a pitch of 1.0 mm, and slice thickness of 1.0 mm to ensure detailed imaging of the ankle. Upon confirming eligibility of 100 patients, assessments were performed using the PACS system’s tools. At the axial level, measurements such as AMI, IMI, MTI, and MIMI were recorded to one decimal point. To mitigate recall bias, each measurement was taken thrice by two researchers independently with at least one week apart. Intra-observer and inter-observer reliabilities were assessed from these measurements. Measurement Methods Axis of Talus (Line M) [ 27 ] (Fig. 1 a): The procedure began by identifying the articular plane at the upper talus. Line A defined the lateral border axis between the talus and fibula, while Line B mapped the axis between the talus and tibia. Line C linked the anterior endpoints of Lines A and B, marking the talus’s anterior border. Line D linked the posterior endpoints, defining the posterior border. Points 'c' and 'd' marked the midpoints of Lines C and D, respectively. Line M ran through these points, establishing the talus’s axis. Point 'O' represented the midpoint of Line 'cd,' marking the talus’s center. Additionally, Line 'L' was a tangent to the lateral malleolus joint surface, and Line ‘N’ was tangent to the medial malleolus surface. Evaluation of AMI and MTI [ 27 – 32 ] (Fig. 1 b): Line M delineates the central axis of the talus, and Line N runs tangent to the medial malleolus’s articular surface. Line 1, originating from the anterior margin of the medial malleolus, is oriented perpendicularly to Line M. Line 2, extending from the anterior margin of the lateral malleolus, intersects both Line 1 and Line M. The angle between Lines 1 and 2 defines the AMI, while the angle between Line 1 and Line N constitutes the MTI. A negative AMI value indicates a posterior positioning of the lateral malleolus relative to Line 1. Conversely, a positive value suggests an anterior positioning, with smaller values indicating a more posterior fibular alignment. Determination of IMI [ 28 , 32 , 33 ] (Fig. 2 a): Line N is tangent to the medial malleolus’s articular surface. Line 3, commencing at the medial malleolus’s anterior edge and perpendicular to Line N, and Line 4, starting at the lateral malleolus’s anterior edge and intersecting both Line 3 and Line N, form the Inter-Malleolar Index (IMI). The angle between Lines 3 and 4 is identified as the IMI, with positive and negative values reflecting the same relational implications as the AMI. Localization of Midpoints of Fibula and Tibia (Fig. 2 b): Line L serves as the tangent to the lateral malleolus’s articular surface, Line M as the central axis of the talus, and Line N as the tangent to the medial malleolus’s articular surface. A line orthogonal to the anterior and posterior boundaries of the fibula marks the fibula’s projection, termed 'F,' and its midpoint ‘f’ aligns with the lateral malleolus’s center. Similarly, a line perpendicular to the tibia’s anterior and posterior boundaries delineates the tibia’s projection, labeled ‘T,’ with its midpoint ‘t’ aligning with the medial malleolus’s center. Measurement of MIMI (Fig. 3 ): Line L acts as the tangent to the lateral malleolus’s articular surface, and Line M is identified as the central axis of the talus. Line N functions as the tangent to the medial malleolus’s articular surface. Line 5, perpendicular to Line N and intersecting at point ‘t,’ sets the tibial axis. Line 6 links midpoint ‘f’ of the fibula with midpoint ‘t’ of the tibia. The angle between Lines 5 and 6, designated as MIMI, interprets positive and negative values with implications analogous to those of AMI. Statistical Analysis A priori power analysis was conducted to determine the necessary sample size for the study. With an effect size of 0.6, a significance level (α) of 0.05, and a power of 0.8, a minimum of 45 cases per group was required. In this study, each group consisted of 50 participants, thus meeting the statistical criteria. Intra- and inter-observer reliabilities were assessed using the intraclass correlation coefficient (ICC). Data analysis was performed using SPSS version 18.0 (IBM Corporation, USA). Descriptive statistics are reported as mean ± standard deviation. For normally distributed or approximately normally distributed data, independent sample t-tests were used, while non-parametric rank-sum tests were applied to data not meeting normality assumptions. Comparisons of affected side and gender distribution were conducted using appropriate statistical tests. Statistical significance was set at P 0.05).Table 1 . Imaging Indices AMI ( P = 0.12), IMI ( P = 0.24), and MIMI ( P = 0.18) showed no significant differences. MTI was significantly lower in CAI patients ( P = 0.03).Table 2 . Table 1 Comparison of General Characteristics Between the Two Groups Group Sex Male/female Side Left/right Age (years) Height (mm) Weight (kg) BMI (kg/㎡) Experime-ntal 31/19 23/27 30.48 ± 9.96 171.18 ± 7.88 70.41 ± 11.33 23.92 ± 2.82 Control 31/19 21/29 30.06 ± 6.86 170.66 ± 7.26 69.70 ± 9.31 23.87 ± 2.30 Statistical value - χ 2 = 0.162 t = 0.246 t = 0.343 t = 0.342 t = 0.098 P value - 0.687 0.806 0.732 0.733 0.922 BMI Body Mass Index. Table 2 Independent Sample t-tests Results Group AMI(°) IMI(°) MTI(°) MIMI(°) Experi-mental -0.86 ± 6.57 -7.00 ± 3.66 83.9 ± 4.33 -7.30 ± 3.42 Control -2.14 ± 7.48 -6.32 ± 4.37 85.68 ± 3.75 -6.26 ± 4.27 t value 0.909 0.199 2.196 1.344 P value 0.365 0.401 0.030* 0.182 AMI Axial Malleolar Index, IMI Intermalleolar Index, MTI Malleolar Talus Index, MIMI Midpoint Intermalleolar Index, *Statistically significant ( p < 0.05). Discussion This study assessed the positions of the fibula and talus in patients with CAI using CT axial images of the ankle joint. The results showed no significant differences in the AMI, IMI, and MIMI between the groups, indicating no change in the fibula’s position on the CT axis in CAI patients. However, a reduced MTI suggests possible external rotation of the talus. Previous research used AMI to assess the position of the fibula, but found it insufficient. AMI was first proposed by Scranton et al. [ 27 ] to evaluate fibular positioning on CT axial images of the ankle joint. Their findings indicated a reduction in AMI among CAI patients, suggesting a posterior position of the fibula. Mcdermott et al. [ 31 ] concluded that CAI patients’ ankles are less stable and more prone to sprains due to the fibula’s posterior position. Similarly, Eren [ 29 ] and Berkowitz [ 30 ] reached comparable conclusions using the same metrics. In our study, no significant differences were found in AMI between the groups, but the method has limitations, such as individual variations in talus size and shape, which may affect measurements and lead to incorrect assumptions about fibular positioning. Thus, a need for more precise measurement techniques is evident. The IMI was utilized to assess the position of the fibula. based on a method introduced by LeBrun et al. [ 33 ] derived from Scranton [ 27 ], using the stable medial malleolus as a reference. Their study found significant differences in AMI, but not in IMI, between the control and CAI groups, aligning with our findings of no significant differences in either AMI or IMI, supporting LeBrun et al.’s results [ 33 ]. AMI and IMI were also measured using MRI axial images. Mavi et al. [ 34 ] investigated the fibula’s position in CAI patients, finding it more anteriorly positioned. This study not only used established methods but introduced MIMI to further assess the fibula's position. No significant differences in AMI, IMI, and MIMI were noted between the groups, consistent with findings from Kobayashi [ 21 ] and Li et al. [ 28 ]. Future studies should include stress and weight-bearing CT and MRI scans of the ankle joint to better simulate ankle joint biomechanics, enhancing our understanding of the relative positions of osseous structures in CAI patients and reducing measurement errors due to body positioning variations. Such comprehensive studies could provide deeper insights into biomechanical changes in CAI and more accurate information about the positioning of the talus, fibula, and other ankle joint structures. The MTI was employed to assess the position of the talus. Li et al. [ 28 ] introduced the MTI methodology based on MRI axial images to measure talus rotation within the ankle mortise. Their findings showed increased MTI in CAI patients, suggesting internal rotation of the talus. In contrast, our current study, utilizing CT axial images, indicated a decreased MTI in CAI patients, leading to an alternative hypothesis of possible external rotation of the talus in this group. The reduced MTI aligns with talar external rotation, potentially destabilizing the ankle mortise and predisposing to syndesmotic injury. This external rotation could be a significant factor contributing to injuries of the tibiofibular syndesmosis and the deltoid ligament [ 35 , 36 ]. It may also be associated with concurrent partial injuries to these structures or the development of scar tissue following ATFL injury. Differences in findings might be due to the varied methodologies used. Future studies should compare CT and MRI measurements to clarify these inconsistencies. In a recent study by Yuan et al. [ 32 ], MRI scans of 50 patients with mechanical ankle instability (MAI) and 50 with functional ankle instability (FAI) were analyzed. The results indicated a higher MTI in MAI patients compared to FAI patients, suggesting MTI as a potential discriminative marker between these conditions. Conversely, our study did not differentiate CAI patients into subgroups, yet the MTI values in our CAI cohort were lower than those reported for the FAI and MAI groups in Yuan's study. This discrepancy may be due to different examination techniques. CT imaging, noted for superior bone visualization compared to MRI, which may be influenced by adjacent soft tissues, offers clearer delineation and potentially more accurate measurements. Thus, CT measurements are recommended for enhanced accuracy, although specific comparative studies on CT and MRI’s impact on these measurements are still needed. Strengths and Limitations This study introduced a new measurement method, MIMI, which uses the midpoint of the medial malleolus as a stable reference point. The aim was to minimize the effects of talus rotation and inter-individual variability on measurement accuracy. Despite these improvements, no significant differences were observed between the groups in AMI, IMI, and MIMI ( P > 0.05). It is important to consider that the age range of participants was restricted, recognizing age as a risk factor for CAI. Adolescents under 16 might have open growth plates, and women over 45 could be at increased risk for osteoporosis, which may affect imaging outcomes. The study aims to clarify fibular positioning changes in CAI, enhance understanding of talus rotation, and direct future research. Future investigations should examine both anterior and posterior positions, as well as internal and external rotations of the talus. The study’s limitations include a potential disparity in the male-to-female ratio within the groups, although no significant gender differences were found between the experimental and control groups. Additionally, while CT scans were performed on the same machine, they were not consistently conducted by the same clinician. Conclusion In CAI patients, CT axial images showed no significant change in the relative positioning of the fibula to the talus and tibia. Additionally, an external rotation of the talus may occur. Abbreviations CAI Chronic Ankle Instability CT Computed Tomography PACS Picture Archiving and Communication System AMI Axial Malleolar Index IMI Inter Malleolar Index MTI Malleolar Talus Index CMI Central Malleolar Index MIMI Midpoint Inter Malleolar Index BMI Body Mass Index MRI Magnetic Resonance Imaging ATFL Anterior Talofibular Ligament CAIT Cumberland Ankle Instability Tool ICC Intraclass Correlation Coefficient MAI Mechanical Ankle Instability FAI Functional Ankle Instability Declarations Ethics approval and consent to participate This study was approved by the Institutional Review Board (IRB) of Affiliated Renhe Hospital of China Three Gorges University. The volunteers involved in the study consent to participate in the study. And the written informed consent has been obtained from the volunteers. Statement: This study adhered to the Declaration of Helsinki。 Consent for publication All individual person’s data consent to publish. Availability of data and materials Datasets are available upon reasonable request to the corresponding author. Competing interests The authors declare no competing interests. Funding None. Authors’ contributions JW and YZ designed the study. JW drafted the manuscript. MC and CG performed data collection. YZ conducted statistical analysis. All authors revised and approved the final manuscript. Acknowledgements None. References Herzog MM, Kerr ZY, Marshall SW, et al. Epidemiology of ankle sprains and chronic ankle instability[J]. J Athl Train. 2019;54:603–10. de Azevedo SSA, Sassi LB, Martins TB, et al. Epidemiology of injuries in young volleyball athletes: a systematic review[J]. J Orthop Surg Res. 2023;18:748. Ferran NA, Maffulli N. Epidemiology of sprains of the lateral ankle ligament complex[J]. Foot Ankle Clin. 2006;11:659–62. Bridgman SA, Clement D, Downing A, et al. Population based epidemiology of ankle sprains attending accident and emergency units in the West Midlands of England, and a survey of UK practice for severe ankle sprains[J]. Emerg Med J. 2003;20:508–10. Al AS, Pourkazemi F, Mackey M, et al. The Prevalence of pain in people with chronic ankle instability: A systematic review[J]. J Athl Train. 2019;54:662–70. Hertel J, Corbett RO. An updated model of chronic ankle instability[J]. J Athl Train. 2019;54:572–88. Delahunt E, Remus A. Risk factors for lateral ankle sprains and chronic ankle instability[J]. J Athl Train. 2019;54:611–16. Xue X, Ma T, Li Q, et al. Chronic ankle instability is associated with proprioception deficits: A systematic review and meta-analysis[J]. J Sport Health Sci. 2021;10:182–91. Ferran NA, Oliva F, Maffulli N. Ankle instability[J]. Sports Med Arthrosc Rev. 2009;17:139–45. Bhimani R, Sato G, Saengsin J, et al. Fluoroscopic evaluation of the role of syndesmotic injury in lateral ankle instability in a cadaver model[J]. Foot Ankle Int. 2022;43:1482–92. Tumer N, Vuurberg G, Blankevoort L, et al. Typical shape differences in the subtalar joint bones between subjects with chronic ankle instability and controls[J]. J Orthop Res. 2019;37:1892–902. Kuznia AL, Hernandez AK, Lee LU. Adolescent idiopathic scoliosis: common questions and answers[J]. Am Fam Physician. 2020;101:19–23. Weber P, Gollwitzer H. [Treatment options for femoroacetabular impingement syndrome and osteoarthritis][J]. Orthopadie (Heidelb),2022;51:472 – 82. Gelber PE, Barenius B, Perelli S. Role of alignment and osteotomy in meniscal injuries[J]. Clin Sports Med. 2020;39:211–21. Li OL, Pritchett S, Giffin JR, et al. High tibial osteotomy: an update for radiologists[J]. AJR Am J Roentgenol. 2022;218:701–12. Kim HK, Parikh S. Patellofemoral instability in children: imaging findings and therapeutic approaches[J]. Korean J Radiol. 2022;23:674–87. Lee DH, Choi YS, Potter HG, et al. Reverse total shoulder arthroplasty: an imaging overview[J]. Skeletal Radiol. 2020;49:19–30. Kamalasekar K, Ravikanth R. First carpometacarpal joint anatomy and osteoarthritis: MR imaging overview[J]. Indian J Radiol Imaging. 2021;31:1012–15. Lin YH, Chang FS, Chen KH, et al. Mismatch between femur and tibia coronal alignment in the knee joint: classification of five lower limb types according to femoral and tibial mechanical alignment[J]. BMC Musculoskelet Disord. 2018;19:411. Zhang J, Yang K, Wang C, et al. Risk factors for chronic ankle instability after first episode of lateral ankle sprain: A retrospective analysis of 362 cases[J]. J Sport Health Sci. 2023;12:606–12. Kobayashi T, Koshino Y, Miki T. Abnormalities of foot and ankle alignment in individuals with chronic ankle instability: a systematic review[J]. BMC Musculoskelet Disord. 2021;22:683. Chang SH, Morris BL, Saengsin J, et al. Diagnosis and treatment of chronic lateral ankle instability: review of our biomechanical evidence[J]. J Am Acad Orthop Surg. 2021;29:3–16. Delahunt E, Bleakley CM, Bossard DS, et al. Clinical assessment of acute lateral ankle sprain injuries (ROAST): 2019 consensus statement and recommendations of the International Ankle Consortium[J]. Br J Sports Med. 2018;52:1304–10. Vuurberg G, Wink LM, Blankevoort L, et al. A risk assessment model for chronic ankle instability: indications for early surgical treatment? An observational prospective cohort - study protocol[J]. BMC Musculoskelet Disord. 2018;19:225. Hadadi M, Ebrahimi TI, Ebrahim MM, et al. Cross-cultural adaptation, reliability, and validity of the Persian version of the Cumberland Ankle Instability Tool[J]. Disabil Rehabil. 2017;39:1644–49. Hiller CE, Refshauge KM, Bundy AC, et al. The Cumberland ankle instability tool: a report of validity and reliability testing[J]. Arch Phys Med Rehabil. 2006;87:1235–41. Scranton PJ, Mcdermott JE, Rogers JV. The relationship between chronic ankle instability and variations in mortise anatomy and impingement spurs[J]. Foot Ankle Int. 2000;21:657–64. Li HY, Zhou RS, Hua YH, et al. MRI identification of the fibular and talus position in patients with mechanical ankle instability[J]. Int J Sports Med. 2017;38:546–50. Eren OT, Kucukkaya M, Kabukcuoglu Y, et al. The role of a posteriorly positioned fibula in ankle sprain[J]. Am J Sports Med. 2003;31:995–98. Berkowitz MJ, Kim DH. Fibular position in relation to lateral ankle instability[J]. Foot Ankle Int. 2004;25:318–21. Mcdermott JE, Scranton PJ, Rogers JV. Variations in fibular position, talar length, and anterior talofibular ligament length[J]. Foot Ankle Int. 2004;25:625–29. Yuan C, Zhu G, Wang Z, et al. The fibula and talus position difference in functional and mechanical ankle instability: MRI findings[J]. J Orthop Surg (Hong Kong). 2021;29:616644863. Lebrun CT, Krause JO. Variations in mortise anatomy[J]. Am J Sports Med. 2005;33:852–55. Mavi A, Yildirim H, Gunes H, et al. The fibular incisura of the tibia with recurrent sprained ankle on magnetic resonance imaging[J]. Saudi Med J. 2002;23:845–49. Yuen CP, Lui TH. Distal tibiofibular syndesmosis: anatomy, biomechanics, injury and management[J]. Open Orthop J. 2017;11:670–77. Lee S, Lin J, Hamid KS, et al. Deltoid ligament rupture in ankle fracture: diagnosis and management[J]. J Am Acad Orthop Surg. 2019;27:e648–58. 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. 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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-6744677","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":485747972,"identity":"3c4d429c-803f-4963-b3fa-afd89fb91939","order_by":0,"name":"Jie Wang","email":"","orcid":"","institution":"Affiliated Renhe Hospital of China Three Gorges University","correspondingAuthor":false,"prefix":"","firstName":"Jie","middleName":"","lastName":"Wang","suffix":""},{"id":485747973,"identity":"2cf3e00c-b15e-4067-82c6-4c67bb868bf4","order_by":1,"name":"Ming-liang Chen","email":"","orcid":"","institution":"Affiliated Renhe Hospital of China Three 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Zhou","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA1ElEQVRIiWNgGAWjYDACCQglx8bM2PggoaKGeC3G/OzMhw0enDlGvJbEmf1saZIPW5gJ65Cf3XxMmqfisLHBYR6zisQGNgb+9u4EvFoY5xxLk+Y5c1gOpOVG4g4ZBokzZzfg1cIskWMmzdsGseVG4hk2BgOJXPxa2KBaEjcAtRQktjET1sID0zKzmS2NgSgtEhJpyZZzzqQb8zMzH5ZIOHOMh6Bf5GckH7zxpsJajo3/YOPHHxU1cvztvfi1gAATD7JLCSoHAcYfRCkbBaNgFIyCEQsAjexD4MyCTLwAAAAASUVORK5CYII=","orcid":"","institution":"Affiliated Renhe Hospital of China Three Gorges University","correspondingAuthor":true,"prefix":"","firstName":"You","middleName":"","lastName":"Zhou","suffix":""}],"badges":[],"createdAt":"2025-05-25 15:53:23","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6744677/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6744677/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":87048913,"identity":"ef2ee243-d0dc-430d-8d77-e50a18da4fc4","added_by":"auto","created_at":"2025-07-18 14:52:25","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":516934,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ea Axis of Talus (Line M)\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eb AMI and MTI\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Fig.1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6744677/v1/4c67f913c6892064c33f1527.jpg"},{"id":87048916,"identity":"bfaf09f7-a217-47e8-a4e7-3fb996a8dc9c","added_by":"auto","created_at":"2025-07-18 14:52:25","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":483888,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ea IMI\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eb Measurement of Midpoints of Fibula and Tibia\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Fig.2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6744677/v1/a909b0f384105dc8b1ef3b0b.jpg"},{"id":87052594,"identity":"3839f4f2-eb06-468c-8fbf-22ef8dde11c1","added_by":"auto","created_at":"2025-07-18 15:08:24","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":164741,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eMIMI\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Fig.3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6744677/v1/00b236a0addfee460239232f.jpg"},{"id":87054575,"identity":"a4037513-27fb-4d09-909e-e264519df752","added_by":"auto","created_at":"2025-07-18 15:24:29","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1876418,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6744677/v1/ca109b28-4c78-4f2b-9def-137285376721.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Evaluation of Fibula and Talus Position in Patients with Chronic Ankle Instability Using Computed Tomography","fulltext":[{"header":"Background","content":"\u003cp\u003eAnkle sprains are among the most prevalent musculoskeletal injuries, with up to 40% progressing to chronic ankle instability (CAI) [\u003cspan additionalcitationids=\"CR2 CR3\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. CAI is characterized by persistent pain, recurrent giving-way episodes, and functional impairment, often culminating in post-traumatic osteoarthritis[\u003cspan additionalcitationids=\"CR6 CR7 CR8\" citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. While ligamentous laxity is a well-established contributor, emerging evidence implicates bony alignment alterations\u0026mdash;particularly fibular malpositioning and talar rotation\u0026mdash;as potential etiological factors[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eConventional diagnostic modalities for CAI include stress radiography and magnetic resonance imaging (MRI) [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Imaging measurements play a pivotal role in orthopedics and greatly enhance clinical practice [\u003cspan additionalcitationids=\"CR13 CR14 CR15 CR16 CR17 CR18\" citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e].However, due to inherent biases in subjective questionnaires and physical examinations, results may yield false-positive or false-negative outcomes influenced by variations among different operators and patients. Therefore, the diagnosis of CAI relies heavily on imaging techniques, primarily stress X-rays and magnetic resonance imaging (MRI), which are relatively accurate and crucial as indirect imaging changes also assist in diagnosing CAI.\u003c/p\u003e\u003cp\u003eThe high incidence of CAI can be attributed to a multifactorial approach, wherein changes in bony structures serve as significant intrinsic anatomical risk factors, including the positioning of the fibula and the rotation of the talus [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. These alterations may contribute to the etiology of recurrent sprains or may be a consequence of CAI, a dynamic process. Previous studies have sparked discussions regarding the positional changes of the talus and fibula in patients with CAI [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. This study is designed to evaluate the positional alterations of the talus and fibula in CAI patients using CT. This study introduces the Midpoint Intermalleolar Index (MIMI), a novel measurement designed to mitigate individual anatomical variability, and evaluates its diagnostic value alongside traditional indices.The purpose of this research is to apply both traditional and novel measurement approaches to more accurately determine the positional variations in the talus and fibula of CAI patients. We hypothesize that there are no substantial changes in the positioning of the talus and fibula in subjects suffering from CAI.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eStudy Design and Participants\u003c/h2\u003e\u003cp\u003e This study was approved by the Institutional Review Board (IRB) of Affiliated Renhe Hospital of China Three Gorges University[Hospital Name] (Ethics Review No. 2023ky16). The volunteers involved in the study consent to participate in the study. And the written informed consent has been obtained from the volunteers.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eSelection of Study Subjects\u003c/h3\u003e\n\u003cp\u003eA retrospective cohort study was conducted on 50 patients diagnosed with CAI who were treated at our hospital from July 1, 2018, to July 1, 2023, comprising 31 males and 19 females (experimental group). For comparative analysis, a control group was established, including 50 individuals (31 males and 19 females) treated for unrelated conditions such as ankle synovitis, soft tissue injuries, and skin lacerations. These control subjects exhibited no injuries to ankle bones or ligaments and had no history of ankle sprains.\u003c/p\u003e\n\u003ch3\u003eCriteria for Inclusion and Exclusion\u003c/h3\u003e\n\u003cp\u003eInclusion criteria [20, 22\u0026ndash;24 ] consisted of: (1) recurrent ankle sprains or a sensation of instability; (2) difficulty walking on uneven terrain; (3) at least one enduring symptom like pain, swelling, or weakness; (4) positive outcomes on anterior drawer or talar tilt tests; (5) MRI signs of damage to the anterior talofibular ligament, possibly involving the calcaneofibular ligament; (6) arthroscopic verification of ligament damage; and (7) a Cumberland Ankle Instability Tool (CAIT) score under 24 [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eExclusion criteria encompassed: (1) previous ankle or lower limb surgery; (2) deformities in adjacent joints or skeletal anomalies including flat feet, high arches, or inward heel rotation; (3) recent ankle sprains, inferior tibiofibular syndesmosis injuries, medial deltoid ligament injuries, or any surrounding bone damage; (4) osteochondral lesions of the talus or cystic bone changes near the ankle; (5) age under 16 or over 45, considering developmental and osteoporotic changes that could affect measurements.\u003c/p\u003e\n\u003ch3\u003eImaging Protocol\u003c/h3\u003e\n\u003cp\u003ePhilips Ingenuity 128 spiral CT was employed for scanning. Patients were positioned supine with the ankle relaxed. Axial, coronal, and sagittal views were captured. Parameters set included a tube voltage of 120 kV, current of 150 mAs, a pitch of 1.0 mm, and slice thickness of 1.0 mm to ensure detailed imaging of the ankle.\u003c/p\u003e\u003cp\u003eUpon confirming eligibility of 100 patients, assessments were performed using the PACS system\u0026rsquo;s tools. At the axial level, measurements such as AMI, IMI, MTI, and MIMI were recorded to one decimal point. To mitigate recall bias, each measurement was taken thrice by two researchers independently with at least one week apart. Intra-observer and inter-observer reliabilities were assessed from these measurements.\u003c/p\u003e\n\u003ch3\u003eMeasurement Methods\u003c/h3\u003e\n\u003cp\u003e\u003cb\u003eAxis of Talus (Line M)\u003c/b\u003e[\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e] (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea): The procedure began by identifying the articular plane at the upper talus. Line A defined the lateral border axis between the talus and fibula, while Line B mapped the axis between the talus and tibia. Line C linked the anterior endpoints of Lines A and B, marking the talus\u0026rsquo;s anterior border. Line D linked the posterior endpoints, defining the posterior border. Points 'c' and 'd' marked the midpoints of Lines C and D, respectively. Line M ran through these points, establishing the talus\u0026rsquo;s axis. Point 'O' represented the midpoint of Line 'cd,' marking the talus\u0026rsquo;s center. Additionally, Line 'L' was a tangent to the lateral malleolus joint surface, and Line \u0026lsquo;N\u0026rsquo; was tangent to the medial malleolus surface.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eEvaluation of AMI and MTI\u003c/b\u003e [\u003cspan additionalcitationids=\"CR28 CR29 CR30 CR31\" citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e] (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb): Line M delineates the central axis of the talus, and Line N runs tangent to the medial malleolus\u0026rsquo;s articular surface. Line 1, originating from the anterior margin of the medial malleolus, is oriented perpendicularly to Line M. Line 2, extending from the anterior margin of the lateral malleolus, intersects both Line 1 and Line M. The angle between Lines 1 and 2 defines the AMI, while the angle between Line 1 and Line N constitutes the MTI. A negative AMI value indicates a posterior positioning of the lateral malleolus relative to Line 1. Conversely, a positive value suggests an anterior positioning, with smaller values indicating a more posterior fibular alignment.\u003c/p\u003e\u003cp\u003e\u003cb\u003eDetermination of IMI\u003c/b\u003e [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e] (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea): Line N is tangent to the medial malleolus\u0026rsquo;s articular surface. Line 3, commencing at the medial malleolus\u0026rsquo;s anterior edge and perpendicular to Line N, and Line 4, starting at the lateral malleolus\u0026rsquo;s anterior edge and intersecting both Line 3 and Line N, form the Inter-Malleolar Index (IMI). The angle between Lines 3 and 4 is identified as the IMI, with positive and negative values reflecting the same relational implications as the AMI.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eLocalization of Midpoints of Fibula and Tibia\u003c/b\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb): Line L serves as the tangent to the lateral malleolus\u0026rsquo;s articular surface, Line M as the central axis of the talus, and Line N as the tangent to the medial malleolus\u0026rsquo;s articular surface. A line orthogonal to the anterior and posterior boundaries of the fibula marks the fibula\u0026rsquo;s projection, termed 'F,' and its midpoint \u0026lsquo;f\u0026rsquo; aligns with the lateral malleolus\u0026rsquo;s center. Similarly, a line perpendicular to the tibia\u0026rsquo;s anterior and posterior boundaries delineates the tibia\u0026rsquo;s projection, labeled \u0026lsquo;T,\u0026rsquo; with its midpoint \u0026lsquo;t\u0026rsquo; aligning with the medial malleolus\u0026rsquo;s center.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eMeasurement of MIMI\u003c/b\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e): Line L acts as the tangent to the lateral malleolus\u0026rsquo;s articular surface, and Line M is identified as the central axis of the talus. Line N functions as the tangent to the medial malleolus\u0026rsquo;s articular surface. Line 5, perpendicular to Line N and intersecting at point \u0026lsquo;t,\u0026rsquo; sets the tibial axis. Line 6 links midpoint \u0026lsquo;f\u0026rsquo; of the fibula with midpoint \u0026lsquo;t\u0026rsquo; of the tibia. The angle between Lines 5 and 6, designated as MIMI, interprets positive and negative values with implications analogous to those of AMI.\u003c/p\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003eStatistical Analysis\u003c/h2\u003e\u003cp\u003eA priori power analysis was conducted to determine the necessary sample size for the study. With an effect size of 0.6, a significance level (α) of 0.05, and a power of 0.8, a minimum of 45 cases per group was required. In this study, each group consisted of 50 participants, thus meeting the statistical criteria. Intra- and inter-observer reliabilities were assessed using the intraclass correlation coefficient (ICC). Data analysis was performed using SPSS version 18.0 (IBM Corporation, USA). Descriptive statistics are reported as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation. For normally distributed or approximately normally distributed data, independent sample t-tests were used, while non-parametric rank-sum tests were applied to data not meeting normality assumptions. Comparisons of affected side and gender distribution were conducted using appropriate statistical tests. Statistical significance was set at \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e\u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cstrong\u003eReliability\u003c/strong\u003e\u003cp\u003eICC values ranged 0.804\u0026ndash;0.921, indicating excellent reproducibility.\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eDemographics\u003c/strong\u003e\u003cp\u003eNo significant intergroup differences in age, gender, or BMI (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05).Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eImaging Indices\u003c/strong\u003e\u003cp\u003eAMI (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.12), IMI (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.24), and MIMI (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.18) showed no significant differences. MTI was significantly lower in CAI patients (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.03).Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eComparison of General Characteristics Between the Two Groups\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\u003eGroup\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSex\u003c/p\u003e\u003cp\u003eMale/female\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eSide\u003c/p\u003e\u003cp\u003eLeft/right\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eAge\u003c/p\u003e\u003cp\u003e(years)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eHeight\u003c/p\u003e\u003cp\u003e(mm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eWeight\u003c/p\u003e\u003cp\u003e(kg)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eBMI\u003c/p\u003e\u003cp\u003e(kg/㎡)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eExperime-ntal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e31/19\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e23/27\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e30.48\u0026thinsp;\u0026plusmn;\u0026thinsp;9.96\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e171.18\u0026thinsp;\u0026plusmn;\u0026thinsp;7.88\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e70.41\u0026thinsp;\u0026plusmn;\u0026thinsp;11.33\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e23.92\u0026thinsp;\u0026plusmn;\u0026thinsp;2.82\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eControl\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e31/19\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e21/29\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e30.06\u0026thinsp;\u0026plusmn;\u0026thinsp;6.86\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e170.66\u0026thinsp;\u0026plusmn;\u0026thinsp;7.26\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e69.70\u0026thinsp;\u0026plusmn;\u0026thinsp;9.31\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e23.87\u0026thinsp;\u0026plusmn;\u0026thinsp;2.30\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eStatistical value\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eχ\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.162\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cem\u003et\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.246\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cem\u003et\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.343\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cem\u003et\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.342\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cem\u003et\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.098\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003eP\u003c/em\u003e value\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.687\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.806\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.732\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.733\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.922\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\u003e\u003cem\u003eBMI\u003c/em\u003e Body Mass Index.\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\u003eIndependent Sample t-tests Results\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\u003eGroup\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAMI(\u0026deg;)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eIMI(\u0026deg;)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMTI(\u0026deg;)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eMIMI(\u0026deg;)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eExperi-mental\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e-0.86\u0026thinsp;\u0026plusmn;\u0026thinsp;6.57\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-7.00\u0026thinsp;\u0026plusmn;\u0026thinsp;3.66\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e83.9\u0026thinsp;\u0026plusmn;\u0026thinsp;4.33\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-7.30\u0026thinsp;\u0026plusmn;\u0026thinsp;3.42\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eControl\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e-2.14\u0026thinsp;\u0026plusmn;\u0026thinsp;7.48\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-6.32\u0026thinsp;\u0026plusmn;\u0026thinsp;4.37\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e85.68\u0026thinsp;\u0026plusmn;\u0026thinsp;3.75\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-6.26\u0026thinsp;\u0026plusmn;\u0026thinsp;4.27\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003et\u003c/em\u003e value\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.909\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.199\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2.196\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.344\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003eP\u003c/em\u003e value\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.365\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.401\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.030*\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.182\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\u003e\u003cem\u003eAMI\u003c/em\u003e Axial Malleolar Index, \u003cem\u003eIMI\u003c/em\u003e Intermalleolar Index, \u003cem\u003eMTI\u003c/em\u003e Malleolar Talus Index, \u003cem\u003eMIMI\u003c/em\u003e Midpoint Intermalleolar Index, *Statistically significant (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study assessed the positions of the fibula and talus in patients with CAI using CT axial images of the ankle joint. The results showed no significant differences in the AMI, IMI, and MIMI between the groups, indicating no change in the fibula\u0026rsquo;s position on the CT axis in CAI patients. However, a reduced MTI suggests possible external rotation of the talus.\u003c/p\u003e\u003cp\u003ePrevious research used AMI to assess the position of the fibula, but found it insufficient. AMI was first proposed by Scranton et al. [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e] to evaluate fibular positioning on CT axial images of the ankle joint. Their findings indicated a reduction in AMI among CAI patients, suggesting a posterior position of the fibula. Mcdermott et al. [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e] concluded that CAI patients\u0026rsquo; ankles are less stable and more prone to sprains due to the fibula\u0026rsquo;s posterior position. Similarly, Eren [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e] and Berkowitz [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e] reached comparable conclusions using the same metrics. In our study, no significant differences were found in AMI between the groups, but the method has limitations, such as individual variations in talus size and shape, which may affect measurements and lead to incorrect assumptions about fibular positioning. Thus, a need for more precise measurement techniques is evident.\u003c/p\u003e\u003cp\u003eThe IMI was utilized to assess the position of the fibula. based on a method introduced by LeBrun et al. [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e] derived from Scranton [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e], using the stable medial malleolus as a reference. Their study found significant differences in AMI, but not in IMI, between the control and CAI groups, aligning with our findings of no significant differences in either AMI or IMI, supporting LeBrun et al.\u0026rsquo;s results [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eAMI and IMI were also measured using MRI axial images. Mavi et al. [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e] investigated the fibula\u0026rsquo;s position in CAI patients, finding it more anteriorly positioned. This study not only used established methods but introduced MIMI to further assess the fibula's position. No significant differences in AMI, IMI, and MIMI were noted between the groups, consistent with findings from Kobayashi [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e] and Li et al. [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. Future studies should include stress and weight-bearing CT and MRI scans of the ankle joint to better simulate ankle joint biomechanics, enhancing our understanding of the relative positions of osseous structures in CAI patients and reducing measurement errors due to body positioning variations. Such comprehensive studies could provide deeper insights into biomechanical changes in CAI and more accurate information about the positioning of the talus, fibula, and other ankle joint structures.\u003c/p\u003e\u003cp\u003eThe MTI was employed to assess the position of the talus. Li et al. [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e] introduced the MTI methodology based on MRI axial images to measure talus rotation within the ankle mortise. Their findings showed increased MTI in CAI patients, suggesting internal rotation of the talus. In contrast, our current study, utilizing CT axial images, indicated a decreased MTI in CAI patients, leading to an alternative hypothesis of possible external rotation of the talus in this group. The reduced MTI aligns with talar external rotation, potentially destabilizing the ankle mortise and predisposing to syndesmotic injury. This external rotation could be a significant factor contributing to injuries of the tibiofibular syndesmosis and the deltoid ligament [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. It may also be associated with concurrent partial injuries to these structures or the development of scar tissue following ATFL injury. Differences in findings might be due to the varied methodologies used. Future studies should compare CT and MRI measurements to clarify these inconsistencies.\u003c/p\u003e\u003cp\u003eIn a recent study by Yuan et al. [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e], MRI scans of 50 patients with mechanical ankle instability (MAI) and 50 with functional ankle instability (FAI) were analyzed. The results indicated a higher MTI in MAI patients compared to FAI patients, suggesting MTI as a potential discriminative marker between these conditions. Conversely, our study did not differentiate CAI patients into subgroups, yet the MTI values in our CAI cohort were lower than those reported for the FAI and MAI groups in Yuan's study. This discrepancy may be due to different examination techniques. CT imaging, noted for superior bone visualization compared to MRI, which may be influenced by adjacent soft tissues, offers clearer delineation and potentially more accurate measurements. Thus, CT measurements are recommended for enhanced accuracy, although specific comparative studies on CT and MRI\u0026rsquo;s impact on these measurements are still needed.\u003c/p\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003eStrengths and Limitations\u003c/h2\u003e\u003cp\u003eThis study introduced a new measurement method, MIMI, which uses the midpoint of the medial malleolus as a stable reference point. The aim was to minimize the effects of talus rotation and inter-individual variability on measurement accuracy. Despite these improvements, no significant differences were observed between the groups in AMI, IMI, and MIMI (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05). It is important to consider that the age range of participants was restricted, recognizing age as a risk factor for CAI. Adolescents under 16 might have open growth plates, and women over 45 could be at increased risk for osteoporosis, which may affect imaging outcomes. The study aims to clarify fibular positioning changes in CAI, enhance understanding of talus rotation, and direct future research. Future investigations should examine both anterior and posterior positions, as well as internal and external rotations of the talus.\u003c/p\u003e\u003cp\u003eThe study\u0026rsquo;s limitations include a potential disparity in the male-to-female ratio within the groups, although no significant gender differences were found between the experimental and control groups. Additionally, while CT scans were performed on the same machine, they were not consistently conducted by the same clinician.\u003c/p\u003e\u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eIn CAI patients, CT axial images showed no significant change in the relative positioning of the fibula to the talus and tibia. Additionally, an external rotation of the talus may occur.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eCAI\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eChronic Ankle Instability\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eCT\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eComputed Tomography\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003ePACS\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003ePicture Archiving and Communication System\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eAMI\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eAxial Malleolar Index\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eIMI\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eInter Malleolar Index\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eMTI\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eMalleolar Talus Index\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eCMI\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eCentral Malleolar Index\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eMIMI\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eMidpoint Inter Malleolar Index\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eBMI\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eBody Mass Index\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eMRI\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eMagnetic Resonance Imaging\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eATFL\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eAnterior Talofibular Ligament\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eCAIT\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eCumberland Ankle Instability Tool\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eICC\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eIntraclass Correlation Coefficient\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eMAI\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eMechanical Ankle Instability\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eFAI\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eFunctional Ankle Instability\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was approved by the Institutional Review Board (IRB) of Affiliated Renhe Hospital of China Three Gorges University. The volunteers involved in the study consent to participate in the study. And the written informed consent has been obtained from the volunteers.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatement:\u0026nbsp;\u003c/strong\u003eThis study adhered to the Declaration of Helsinki。\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll individual person\u0026rsquo;s data consent to publish.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDatasets are available upon reasonable request to the corresponding author.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNone.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026rsquo; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eJW and YZ designed the study. JW drafted the manuscript. MC and CG performed data collection. YZ conducted statistical analysis. All authors revised and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNone.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eHerzog MM, Kerr ZY, Marshall SW, et al. Epidemiology of ankle sprains and chronic ankle instability[J]. J Athl Train. 2019;54:603\u0026ndash;10.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ede Azevedo SSA, Sassi LB, Martins TB, et al. Epidemiology of injuries in young volleyball athletes: a systematic review[J]. J Orthop Surg Res. 2023;18:748.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFerran NA, Maffulli N. Epidemiology of sprains of the lateral ankle ligament complex[J]. Foot Ankle Clin. 2006;11:659\u0026ndash;62.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBridgman SA, Clement D, Downing A, et al. Population based epidemiology of ankle sprains attending accident and emergency units in the West Midlands of England, and a survey of UK practice for severe ankle sprains[J]. Emerg Med J. 2003;20:508\u0026ndash;10.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAl AS, Pourkazemi F, Mackey M, et al. The Prevalence of pain in people with chronic ankle instability: A systematic review[J]. J Athl Train. 2019;54:662\u0026ndash;70.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHertel J, Corbett RO. An updated model of chronic ankle instability[J]. J Athl Train. 2019;54:572\u0026ndash;88.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDelahunt E, Remus A. Risk factors for lateral ankle sprains and chronic ankle instability[J]. J Athl Train. 2019;54:611\u0026ndash;16.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eXue X, Ma T, Li Q, et al. Chronic ankle instability is associated with proprioception deficits: A systematic review and meta-analysis[J]. J Sport Health Sci. 2021;10:182\u0026ndash;91.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFerran NA, Oliva F, Maffulli N. Ankle instability[J]. Sports Med Arthrosc Rev. 2009;17:139\u0026ndash;45.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBhimani R, Sato G, Saengsin J, et al. Fluoroscopic evaluation of the role of syndesmotic injury in lateral ankle instability in a cadaver model[J]. Foot Ankle Int. 2022;43:1482\u0026ndash;92.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eTumer N, Vuurberg G, Blankevoort L, et al. Typical shape differences in the subtalar joint bones between subjects with chronic ankle instability and controls[J]. J Orthop Res. 2019;37:1892\u0026ndash;902.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKuznia AL, Hernandez AK, Lee LU. Adolescent idiopathic scoliosis: common questions and answers[J]. Am Fam Physician. 2020;101:19\u0026ndash;23.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWeber P, Gollwitzer H. [Treatment options for femoroacetabular impingement syndrome and osteoarthritis][J]. Orthopadie (Heidelb),2022;51:472\u0026thinsp;\u0026ndash;\u0026thinsp;82.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGelber PE, Barenius B, Perelli S. Role of alignment and osteotomy in meniscal injuries[J]. Clin Sports Med. 2020;39:211\u0026ndash;21.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLi OL, Pritchett S, Giffin JR, et al. High tibial osteotomy: an update for radiologists[J]. AJR Am J Roentgenol. 2022;218:701\u0026ndash;12.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKim HK, Parikh S. Patellofemoral instability in children: imaging findings and therapeutic approaches[J]. Korean J Radiol. 2022;23:674\u0026ndash;87.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLee DH, Choi YS, Potter HG, et al. Reverse total shoulder arthroplasty: an imaging overview[J]. Skeletal Radiol. 2020;49:19\u0026ndash;30.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKamalasekar K, Ravikanth R. First carpometacarpal joint anatomy and osteoarthritis: MR imaging overview[J]. Indian J Radiol Imaging. 2021;31:1012\u0026ndash;15.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLin YH, Chang FS, Chen KH, et al. Mismatch between femur and tibia coronal alignment in the knee joint: classification of five lower limb types according to femoral and tibial mechanical alignment[J]. BMC Musculoskelet Disord. 2018;19:411.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZhang J, Yang K, Wang C, et al. Risk factors for chronic ankle instability after first episode of lateral ankle sprain: A retrospective analysis of 362 cases[J]. J Sport Health Sci. 2023;12:606\u0026ndash;12.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKobayashi T, Koshino Y, Miki T. Abnormalities of foot and ankle alignment in individuals with chronic ankle instability: a systematic review[J]. BMC Musculoskelet Disord. 2021;22:683.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eChang SH, Morris BL, Saengsin J, et al. Diagnosis and treatment of chronic lateral ankle instability: review of our biomechanical evidence[J]. J Am Acad Orthop Surg. 2021;29:3\u0026ndash;16.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDelahunt E, Bleakley CM, Bossard DS, et al. Clinical assessment of acute lateral ankle sprain injuries (ROAST): 2019 consensus statement and recommendations of the International Ankle Consortium[J]. Br J Sports Med. 2018;52:1304\u0026ndash;10.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eVuurberg G, Wink LM, Blankevoort L, et al. A risk assessment model for chronic ankle instability: indications for early surgical treatment? An observational prospective cohort - study protocol[J]. BMC Musculoskelet Disord. 2018;19:225.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHadadi M, Ebrahimi TI, Ebrahim MM, et al. Cross-cultural adaptation, reliability, and validity of the Persian version of the Cumberland Ankle Instability Tool[J]. Disabil Rehabil. 2017;39:1644\u0026ndash;49.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHiller CE, Refshauge KM, Bundy AC, et al. The Cumberland ankle instability tool: a report of validity and reliability testing[J]. Arch Phys Med Rehabil. 2006;87:1235\u0026ndash;41.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eScranton PJ, Mcdermott JE, Rogers JV. The relationship between chronic ankle instability and variations in mortise anatomy and impingement spurs[J]. Foot Ankle Int. 2000;21:657\u0026ndash;64.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLi HY, Zhou RS, Hua YH, et al. MRI identification of the fibular and talus position in patients with mechanical ankle instability[J]. Int J Sports Med. 2017;38:546\u0026ndash;50.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eEren OT, Kucukkaya M, Kabukcuoglu Y, et al. The role of a posteriorly positioned fibula in ankle sprain[J]. Am J Sports Med. 2003;31:995\u0026ndash;98.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBerkowitz MJ, Kim DH. Fibular position in relation to lateral ankle instability[J]. Foot Ankle Int. 2004;25:318\u0026ndash;21.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMcdermott JE, Scranton PJ, Rogers JV. Variations in fibular position, talar length, and anterior talofibular ligament length[J]. Foot Ankle Int. 2004;25:625\u0026ndash;29.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eYuan C, Zhu G, Wang Z, et al. The fibula and talus position difference in functional and mechanical ankle instability: MRI findings[J]. J Orthop Surg (Hong Kong). 2021;29:616644863.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLebrun CT, Krause JO. Variations in mortise anatomy[J]. Am J Sports Med. 2005;33:852\u0026ndash;55.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMavi A, Yildirim H, Gunes H, et al. The fibular incisura of the tibia with recurrent sprained ankle on magnetic resonance imaging[J]. Saudi Med J. 2002;23:845\u0026ndash;49.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eYuen CP, Lui TH. Distal tibiofibular syndesmosis: anatomy, biomechanics, injury and management[J]. Open Orthop J. 2017;11:670\u0026ndash;77.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLee S, Lin J, Hamid KS, et al. Deltoid ligament rupture in ankle fracture: diagnosis and management[J]. J Am Acad Orthop Surg. 2019;27:e648\u0026ndash;58.\u003c/span\u003e\u003c/li\u003e\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":"Chronic ankle instability, Talus, Fibula, Computed tomography, Axial imaging, Biomechanics","lastPublishedDoi":"10.21203/rs.3.rs-6744677/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6744677/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eChronic ankle instability (CAI) is a common sequela of recurrent ankle sprains, yet the role of bony structural changes in its pathogenesis remains debated. This study aimed to evaluate the positional relationships of the fibula and talus in CAI patients using computed tomography (CT).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA retrospective cohort study included 50 CAI patients and 50 controls. Axial CT images were analyzed to measure four indices: Axial Malleolar Index (AMI), Intermalleolar Index (IMI), Malleolar Talus Index (MTI), and Midpoint Intermalleolar Index (MIMI). Intra- and inter-observer reliabilities were assessed via intraclass correlation coefficients (ICC).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDemographic variables (age, gender, BMI) showed no significant intergroup differences. AMI, IMI, and MIMI were comparable between groups (\u003cem\u003eP\u003c/em\u003e \u0026gt; 0.05). However, MTI was significantly reduced in the CAI group (\u003cem\u003eP\u003c/em\u003e \u0026lt; 0.05), suggesting potential external talar rotation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCT axial imaging revealed no significant alterations in fibular positioning relative to the talus or tibia in CAI patients. The observed decrease in MTI may indicate talar external rotation, warranting further investigation into its biomechanical implications.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eLevel of Evidence: \u003c/strong\u003eIII. (DIAGNOSTIC, Retrospective cohort study)\u003c/p\u003e","manuscriptTitle":"Evaluation of Fibula and Talus Position in Patients with Chronic Ankle Instability Using Computed Tomography","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-07-18 14:52:20","doi":"10.21203/rs.3.rs-6744677/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":"b17b1e9c-297b-4cd5-8fd7-79470695e110","owner":[],"postedDate":"July 18th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-07-18T14:52:22+00:00","versionOfRecord":[],"versionCreatedAt":"2025-07-18 14:52:20","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6744677","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6744677","identity":"rs-6744677","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}